//----------------------------------------------------------------------------
//
//                                UNCLASSIFIED
//
// Copyright © 1989-2017 BAE Systems Information and Electronic Systems Integration Inc.
//                            ALL RIGHTS RESERVED
// Use of this software product is governed by the terms of a license
// agreement. The license agreement is found in the installation directory.
//
//             For support, please visit http://www.baesystems.com/gxp
//
//  Revision History:
//  Date        Name         Description
//  ----------- ------------ -----------------------------------------------
//  13-Nov-2015 BAE Systems  Initial Implementation
//  24-Apr-2017 BAE Systems  Update for CSM 3.0.2
//  24-OCT-2017 BAE Systems  Update for CSM 3.0.3
//-----------------------------------------------------------------------------
#include "UsgsAstroLsSensorModel.h"
#include "Utilities.h"
#include "Distortion.h"

#include <algorithm>
#include <iostream>
#include <sstream>
#include <math.h>
#include <float.h>

#include <sstream>
#include <Error.h>
#include <json/json.hpp>

#define MESSAGE_LOG(...) if (m_logger) { m_logger->info(__VA_ARGS__); }

using json = nlohmann::json;
using namespace std;

const std::string UsgsAstroLsSensorModel::_SENSOR_MODEL_NAME
         = "USGS_ASTRO_LINE_SCANNER_SENSOR_MODEL";
const int     UsgsAstroLsSensorModel::NUM_PARAMETERS = 16;
const std::string  UsgsAstroLsSensorModel::PARAMETER_NAME[] =
{
   "IT Pos. Bias   ",   // 0
   "CT Pos. Bias   ",   // 1
   "Rad Pos. Bias  ",   // 2
   "IT Vel. Bias   ",   // 3
   "CT Vel. Bias   ",   // 4
   "Rad Vel. Bias  ",   // 5
   "Omega Bias     ",   // 6
   "Phi Bias       ",   // 7
   "Kappa Bias     ",   // 8
   "Omega Rate     ",   // 9
   "Phi Rate       ",   // 10
   "Kappa Rate     ",   // 11
   "Omega Accl     ",   // 12
   "Phi Accl       ",   // 13
   "Kappa Accl     ",   // 14
   "Focal Bias     "    // 15
};


const std::string  UsgsAstroLsSensorModel::_STATE_KEYWORD[] =
{
   "m_modelName",
   "m_imageIdentifier",
   "m_sensorName",
   "m_nLines",
   "m_nSamples",
   "m_platformFlag",
   "m_intTimeLines",
   "m_intTimeStartTimes",
   "m_intTimes",
   "m_startingEphemerisTime",
   "m_centerEphemerisTime",
   "m_detectorSampleSumming",
   "m_detectorSampleSumming",
   "m_startingDetectorSample",
   "m_startingDetectorLine",
   "m_ikCode",
   "m_focalLength",
   "m_zDirection",
   "m_distortionType",
   "m_opticalDistCoeffs",
   "m_iTransS",
   "m_iTransL",
   "m_detectorSampleOrigin",
   "m_detectorLineOrigin",
   "m_majorAxis",
   "m_minorAxis",
   "m_platformIdentifier",
   "m_sensorIdentifier",
   "m_minElevation",
   "m_maxElevation",
   "m_dtEphem",
   "m_t0Ephem",
   "m_dtQuat",
   "m_t0Quat",
   "m_numPositions",
   "m_numQuaternions",
   "m_positions",
   "m_velocities",
   "m_quaternions",
   "m_currentParameterValue",
   "m_parameterType",
   "m_referencePointXyz",
   "m_sunPosition",
   "m_sunVelocity",
   "m_gsd",
   "m_flyingHeight",
   "m_halfSwath",
   "m_halfTime",
   "m_covariance",
};

const int UsgsAstroLsSensorModel::NUM_PARAM_TYPES = 4;
const std::string UsgsAstroLsSensorModel::PARAM_STRING_ALL[] =
{
   "NONE",
   "FICTITIOUS",
   "REAL",
   "FIXED"
};
const csm::param::Type
      UsgsAstroLsSensorModel::PARAM_CHAR_ALL[] =
{
   csm::param::NONE,
   csm::param::FICTITIOUS,
   csm::param::REAL,
   csm::param::FIXED
};

//***************************************************************************
// UsgsAstroLineScannerSensorModel::replaceModelState
//***************************************************************************
void UsgsAstroLsSensorModel::replaceModelState(const std::string &stateString )
{
   MESSAGE_LOG("Replacing model state")

   reset();
   auto j = json::parse(stateString);
   int num_params    = NUM_PARAMETERS;
   int num_paramsSq = num_params * num_params;

   m_imageIdentifier = j["m_imageIdentifier"].get<std::string>();
   m_sensorName = j["m_sensorName"];
   m_nLines = j["m_nLines"];
   m_nSamples = j["m_nSamples"];
   m_platformFlag = j["m_platformFlag"];
   MESSAGE_LOG("m_imageIdentifier: {} "
                         "m_sensorName: {} "
                         "m_nLines: {} "
                         "m_nSamples: {} "
                         "m_platformFlag: {} ",
                         j["m_imageIdentifier"].dump(),
                         j["m_sensorName"].dump(),
                         j["m_nLines"].dump(),
                         j["m_nSamples"].dump(),
                         j["m_platformFlag"].dump())

   m_intTimeLines = j["m_intTimeLines"].get<std::vector<double>>();
   m_intTimeStartTimes = j["m_intTimeStartTimes"].get<std::vector<double>>();
   m_intTimes = j["m_intTimes"].get<std::vector<double>>();

   m_startingEphemerisTime = j["m_startingEphemerisTime"];
   m_centerEphemerisTime = j["m_centerEphemerisTime"];
   m_detectorSampleSumming = j["m_detectorSampleSumming"];
   m_detectorLineSumming = j["m_detectorLineSumming"];
   m_startingDetectorSample = j["m_startingDetectorSample"];
   m_startingDetectorLine = j["m_startingDetectorLine"];
   m_ikCode = j["m_ikCode"];
   MESSAGE_LOG("m_startingEphemerisTime: {} "
                         "m_centerEphemerisTime: {} "
                         "m_detectorSampleSumming: {} "
                         "m_detectorLineSumming: {} "
                         "m_startingDetectorSample: {} "
                         "m_ikCode: {} ",
                         j["m_startingEphemerisTime"].dump(),
                         j["m_centerEphemerisTime"].dump(),
                         j["m_detectorSampleSumming"].dump(),
                         j["m_detectorLineSumming"].dump(),
                         j["m_startingDetectorSample"].dump(), j["m_ikCode"].dump())

   m_focalLength = j["m_focalLength"];
   m_zDirection = j["m_zDirection"];
   m_distortionType = (DistortionType)j["m_distortionType"].get<int>();
   m_opticalDistCoeffs = j["m_opticalDistCoeffs"].get<std::vector<double>>();
   MESSAGE_LOG("m_focalLength: {} "
                         "m_zDirection: {} "
                         "m_distortionType: {} ",
                         j["m_focalLength"].dump(), j["m_zDirection"].dump(),
                         j["m_distortionType"].dump())

   for (int i = 0; i < 3; i++) {
     m_iTransS[i] = j["m_iTransS"][i];
     m_iTransL[i] = j["m_iTransL"][i];
   }

   m_detectorSampleOrigin = j["m_detectorSampleOrigin"];
   m_detectorLineOrigin = j["m_detectorLineOrigin"];
   m_majorAxis = j["m_majorAxis"];
   m_minorAxis = j["m_minorAxis"];
   MESSAGE_LOG("m_detectorSampleOrigin: {} "
                         "m_detectorLineOrigin: {} "
                         "m_majorAxis: {} "
                         "m_minorAxis: {} ",
                         j["m_detectorSampleOrigin"].dump(),
                         j["m_detectorLineOrigin"].dump(),
                         j["m_majorAxis"].dump(), j["m_minorAxis"].dump())

   m_platformIdentifier = j["m_platformIdentifier"];
   m_sensorIdentifier = j["m_sensorIdentifier"];
   MESSAGE_LOG("m_platformIdentifier: {} "
                         "m_sensorIdentifier: {} ",
                         j["m_platformIdentifier"].dump(),
                         j["m_sensorIdentifier"].dump())

   m_minElevation = j["m_minElevation"];
   m_maxElevation = j["m_maxElevation"];
   MESSAGE_LOG("m_minElevation: {} "
                         "m_maxElevation: {} ",
                         j["m_minElevation"].dump(),
                         j["m_maxElevation"].dump())

   m_dtEphem = j["m_dtEphem"];
   m_t0Ephem = j["m_t0Ephem"];
   m_dtQuat = j["m_dtQuat"];
   m_t0Quat = j["m_t0Quat"];
   m_numPositions = j["m_numPositions"];
   MESSAGE_LOG("m_dtEphem: {} "
                         "m_t0Ephem: {} "
                         "m_dtQuat: {} "
                         "m_t0Quat: {} ",
                         j["m_dtEphem"].dump(), j["m_t0Ephem"].dump(),
                         j["m_dtQuat"].dump(), j["m_t0Quat"].dump())

   m_numQuaternions = j["m_numQuaternions"];
   m_referencePointXyz.x = j["m_referencePointXyz"][0];
   m_referencePointXyz.y = j["m_referencePointXyz"][1];
   m_referencePointXyz.z = j["m_referencePointXyz"][2];
   MESSAGE_LOG("m_numQuaternions: {} "
                         "m_referencePointX: {} "
                         "m_referencePointY: {} "
                         "m_referencePointZ: {} ",
                         j["m_numQuaternions"].dump(), j["m_referencePointXyz"][0].dump(),
                         j["m_referencePointXyz"][1].dump(),
                         j["m_referencePointXyz"][2].dump())

   m_gsd = j["m_gsd"];
   m_flyingHeight = j["m_flyingHeight"];
   m_halfSwath = j["m_halfSwath"];
   m_halfTime = j["m_halfTime"];
   MESSAGE_LOG("m_gsd: {} "
                         "m_flyingHeight: {} "
                         "m_halfSwath: {} "
                         "m_halfTime: {} ",
                         j["m_gsd"].dump(), j["m_flyingHeight"].dump(),
                         j["m_halfSwath"].dump(), j["m_halfTime"].dump())
   // Vector = is overloaded so explicit get with type required.

   m_positions = j["m_positions"].get<std::vector<double>>();
   m_velocities = j["m_velocities"].get<std::vector<double>>();
   m_quaternions = j["m_quaternions"].get<std::vector<double>>();
   m_currentParameterValue = j["m_currentParameterValue"].get<std::vector<double>>();
   m_covariance = j["m_covariance"].get<std::vector<double>>();
   m_sunPosition = j["m_sunPosition"].get<std::vector<double>>();
   m_sunVelocity = j["m_sunVelocity"].get<std::vector<double>>();

   for (int i = 0; i < num_params; i++) {
     for (int k = 0; k < NUM_PARAM_TYPES; k++) {
       if (j["m_parameterType"][i] == PARAM_STRING_ALL[k]) {
         m_parameterType[i] = PARAM_CHAR_ALL[k];
         break;
     }
    }
   }

   // If computed state values are still default, then compute them
   if (m_gsd == 1.0  && m_flyingHeight == 1000.0)
   {
     updateState();
   }

   try
   {
     setLinearApproximation();
   }
   catch (...)
   {
     _linear = false;
   }
}

//***************************************************************************
// UsgsAstroLineScannerSensorModel::getModelNameFromModelState
//***************************************************************************
std::string UsgsAstroLsSensorModel::getModelNameFromModelState(
   const std::string& model_state)
{
   // Parse the string to JSON
   auto j = json::parse(model_state);
   // If model name cannot be determined, return a blank string
   std::string model_name;

   if (j.find("m_modelName") != j.end()) {
       model_name = j["m_modelName"];
   } else {
       csm::Error::ErrorType aErrorType = csm::Error::INVALID_SENSOR_MODEL_STATE;
       std::string aMessage = "No 'm_modelName' key in the model state object.";
       std::string aFunction = "UsgsAstroLsPlugin::getModelNameFromModelState";
       csm::Error csmErr(aErrorType, aMessage, aFunction);
       throw(csmErr);
   }
   if (model_name != _SENSOR_MODEL_NAME){
       csm::Error::ErrorType aErrorType = csm::Error::SENSOR_MODEL_NOT_SUPPORTED;
       std::string aMessage = "Sensor model not supported.";
       std::string aFunction = "UsgsAstroLsPlugin::getModelNameFromModelState()";
       csm::Error csmErr(aErrorType, aMessage, aFunction);
       throw(csmErr);
   }
   return model_name;
}

//***************************************************************************
// UsgsAstroLineScannerSensorModel::getModelState
//***************************************************************************
std::string UsgsAstroLsSensorModel::getModelState() const {
      MESSAGE_LOG("Running getModelState")

      json state;
      state["m_modelName"] = _SENSOR_MODEL_NAME;
      state["m_startingDetectorSample"] = m_startingDetectorSample;
      state["m_startingDetectorLine"] = m_startingDetectorLine;
      state["m_imageIdentifier"] = m_imageIdentifier;
      state["m_sensorName"] = m_sensorName;
      state["m_nLines"] = m_nLines;
      state["m_nSamples"] = m_nSamples;
      state["m_platformFlag"] = m_platformFlag;
      MESSAGE_LOG("m_imageIdentifier: {} "
                                  "m_sensorName: {} "
                                  "m_nLines: {} "
                                  "m_nSamples: {} "
                                  "m_platformFlag: {} ",
                                  m_imageIdentifier, m_sensorName,
                                  m_nLines, m_nSamples, m_platformFlag)

      state["m_intTimeLines"] = m_intTimeLines;
      state["m_intTimeStartTimes"] = m_intTimeStartTimes;
      state["m_intTimes"] = m_intTimes;
      state["m_startingEphemerisTime"] = m_startingEphemerisTime;
      state["m_centerEphemerisTime"] = m_centerEphemerisTime;
      MESSAGE_LOG("m_startingEphemerisTime: {} "
                                  "m_centerEphemerisTime: {} ",
                                  m_startingEphemerisTime,
                                  m_centerEphemerisTime)

      state["m_detectorSampleSumming"] = m_detectorSampleSumming;
      state["m_detectorLineSumming"] = m_detectorLineSumming;
      state["m_startingDetectorSample"] = m_startingDetectorSample;
      state["m_ikCode"] = m_ikCode;
      MESSAGE_LOG("m_detectorSampleSumming: {} "
                            "m_detectorLineSumming: {} "
                            "m_startingDetectorSample: {} "
                            "m_ikCode: {} ",
                            m_detectorSampleSumming, m_detectorLineSumming,
                            m_startingDetectorSample,
                            m_ikCode)

      state["m_focalLength"] = m_focalLength;
      state["m_zDirection"] = m_zDirection;
      state["m_distortionType"] = m_distortionType;
      state["m_opticalDistCoeffs"] = m_opticalDistCoeffs;
      MESSAGE_LOG("m_focalLength: {} "
                                  "m_zDirection: {} "
                                  "m_distortionType (0-Radial, 1-Transverse): {} ",
                                  m_focalLength, m_zDirection,
                                  m_distortionType)

      state["m_iTransS"] = std::vector<double>(m_iTransS, m_iTransS+3);
      state["m_iTransL"] = std::vector<double>(m_iTransL, m_iTransL+3);

      state["m_detectorSampleOrigin"] = m_detectorSampleOrigin;
      state["m_detectorLineOrigin"] = m_detectorLineOrigin;
      state["m_majorAxis"] = m_majorAxis;
      state["m_minorAxis"] = m_minorAxis;
      MESSAGE_LOG("m_detectorSampleOrigin: {} "
                                  "m_detectorLineOrigin: {} "
                                  "m_majorAxis: {} "
                                  "m_minorAxis: {} ",
                                  m_detectorSampleOrigin, m_detectorLineOrigin,
                                  m_majorAxis, m_minorAxis)

      state["m_platformIdentifier"] = m_platformIdentifier;
      state["m_sensorIdentifier"] = m_sensorIdentifier;
      state["m_minElevation"] = m_minElevation;
      state["m_maxElevation"] = m_maxElevation;
      MESSAGE_LOG("m_platformIdentifier: {} "
                                  "m_sensorIdentifier: {} "
                                  "m_minElevation: {} "
                                  "m_maxElevation: {} ",
                                  m_platformIdentifier, m_sensorIdentifier,
                                  m_minElevation, m_maxElevation)

      state["m_dtEphem"] = m_dtEphem;
      state["m_t0Ephem"] = m_t0Ephem;
      state["m_dtQuat"] = m_dtQuat;
      state["m_t0Quat"] = m_t0Quat;
      MESSAGE_LOG("m_dtEphem: {} "
                                  "m_t0Ephem: {} "
                                  "m_dtQuat: {} "
                                  "m_t0Quat: {} ",
                                  m_dtEphem, m_t0Ephem,
                                  m_dtQuat, m_t0Quat)

      state["m_numPositions"] = m_numPositions;
      state["m_numQuaternions"] = m_numQuaternions;
      state["m_positions"] = m_positions;
      state["m_velocities"] = m_velocities;
      state["m_quaternions"] = m_quaternions;
      MESSAGE_LOG("m_numPositions: {} "
                            "m_numQuaternions: {} ",
                             m_numPositions, m_numQuaternions)

      state["m_currentParameterValue"] = m_currentParameterValue;
      state["m_parameterType"] = m_parameterType;

      state["m_gsd"] = m_gsd;
      state["m_flyingHeight"] = m_flyingHeight;
      state["m_halfSwath"] = m_halfSwath;
      state["m_halfTime"] = m_halfTime;
      state["m_covariance"] = m_covariance;
      MESSAGE_LOG("m_gsd: {} "
                            "m_flyingHeight: {} "
                            "m_halfSwath: {} "
                            "m_halfTime: {} ",
                            m_gsd, m_flyingHeight,
                            m_halfSwath, m_halfTime)

      state["m_referencePointXyz"] = json();
      state["m_referencePointXyz"][0] = m_referencePointXyz.x;
      state["m_referencePointXyz"][1] = m_referencePointXyz.y;
      state["m_referencePointXyz"][2] = m_referencePointXyz.z;
      MESSAGE_LOG("m_referencePointXyz: {} "
                            "m_referencePointXyz: {} "
                            "m_referencePointXyz: {} ",
                             m_referencePointXyz.x, m_referencePointXyz.y,
                             m_referencePointXyz.z)

      state["m_sunPosition"] = m_sunPosition;
      MESSAGE_LOG("num sun positions: {} ", m_sunPosition.size())

      state["m_sunVelocity"] = m_sunVelocity;
      MESSAGE_LOG("num sun velocities: {} ", m_sunVelocity.size())

      return state.dump();
 }

 //***************************************************************************
 // UsgsAstroLineScannerSensorModel::reset
 //***************************************************************************
void UsgsAstroLsSensorModel::reset()
{
  MESSAGE_LOG("Running reset()")
  _linear = false; // default until a linear model is made
  _u0    = 0.0;
  _du_dx = 0.0;
  _du_dy = 0.0;
  _du_dz = 0.0;
  _v0    = 0.0;
  _dv_dx = 0.0;
  _dv_dy = 0.0;
  _dv_dz = 0.0;

  _no_adjustment.assign(UsgsAstroLsSensorModel::NUM_PARAMETERS, 0.0);

  m_imageIdentifier = "";                    // 1
  m_sensorName    = "USGSAstroLineScanner";  // 2
  m_nLines    = 0;                       // 3
  m_nSamples  = 0;                       // 4
  m_platformFlag  = 1;                       // 9
  m_intTimeLines.clear();
  m_intTimeStartTimes.clear();
  m_intTimes.clear();
  m_startingEphemerisTime = 0.0;             // 13
  m_centerEphemerisTime = 0.0;               // 14
  m_detectorSampleSumming = 1.0;             // 15
  m_detectorLineSumming = 1.0;
  m_startingDetectorSample = 1.0;                    // 16
  m_ikCode = -85600;                         // 17
  m_focalLength = 350.0;                           // 18
  m_zDirection = 1.0;                        // 19
  m_distortionType = DistortionType::RADIAL;
  m_opticalDistCoeffs = std::vector<double>(3, 0.0);
  m_iTransS[0] = 0.0;                        // 21
  m_iTransS[1] = 0.0;                        // 21
  m_iTransS[2] = 150.0;                      // 21
  m_iTransL[0] = 0.0;                        // 22
  m_iTransL[1] = 150.0;                      // 22
  m_iTransL[2] = 0.0;                        // 22
  m_detectorSampleOrigin = 2500.0;           // 23
  m_detectorLineOrigin = 0.0;                // 24
  m_majorAxis = 3400000.0;               // 27
  m_minorAxis = 3350000.0;               // 28
  m_platformIdentifier = "";                 // 31
  m_sensorIdentifier = "";                   // 32
  m_minElevation = -8000.0;                  // 34
  m_maxElevation =  8000.0;                  // 35
  m_dtEphem = 2.0;                           // 36
  m_t0Ephem = -70.0;                         // 37
  m_dtQuat =  0.1;                           // 38
  m_t0Quat = -40.0;                          // 39
  m_numPositions = 0;                            // 40
  m_numQuaternions = 0;                      // 41
  m_positions.clear();                        // 42
  m_velocities.clear();                      // 43
  m_quaternions.clear();                     // 44

  m_currentParameterValue.assign(NUM_PARAMETERS,0.0);
  m_parameterType.assign(NUM_PARAMETERS,csm::param::REAL);

  m_referencePointXyz.x = 0.0;
  m_referencePointXyz.y = 0.0;
  m_referencePointXyz.z = 0.0;

  m_sunPosition = std::vector<double>(3, 0.0);
  m_sunVelocity = std::vector<double>(3, 0.0);

  m_gsd = 1.0;
  m_flyingHeight = 1000.0;
  m_halfSwath = 1000.0;
  m_halfTime = 10.0;

  m_covariance = std::vector<double>(NUM_PARAMETERS * NUM_PARAMETERS,0.0); // 52

}

//*****************************************************************************
// UsgsAstroLsSensorModel Constructor
//*****************************************************************************
UsgsAstroLsSensorModel::UsgsAstroLsSensorModel()
{
   _no_adjustment.assign(UsgsAstroLsSensorModel::NUM_PARAMETERS, 0.0);
}


//*****************************************************************************
// UsgsAstroLsSensorModel Destructor
//*****************************************************************************
UsgsAstroLsSensorModel::~UsgsAstroLsSensorModel()
{
}

//*****************************************************************************
// UsgsAstroLsSensorModel updateState
//*****************************************************************************
void UsgsAstroLsSensorModel::updateState()
{
   // If sensor model is being created for the first time
   // This routine will set some parameters not found in the ISD.
   MESSAGE_LOG("Updating State")
   // Reference point (image center)
   double lineCtr = m_nLines / 2.0;
   double sampCtr = m_nSamples / 2.0;
   csm::ImageCoord ip(lineCtr, sampCtr);
   MESSAGE_LOG("updateState: center image coordinate set to {} {}",
                               lineCtr, sampCtr)

   double refHeight = 0;
   m_referencePointXyz = imageToGround(ip, refHeight);
   MESSAGE_LOG("updateState: reference point (x, y, z) {} {} {}",
                                m_referencePointXyz.x, m_referencePointXyz.y,
                                m_referencePointXyz.z)

   // Compute ground sample distance
   ip.line += 1;
   ip.samp += 1;
   csm::EcefCoord delta = imageToGround(ip, refHeight);
   double dx = delta.x - m_referencePointXyz.x;
   double dy = delta.y - m_referencePointXyz.y;
   double dz = delta.z - m_referencePointXyz.z;
   m_gsd = sqrt((dx*dx + dy*dy + dz*dz) / 2.0);
   MESSAGE_LOG("updateState: ground sample distance set to {} "
                              "based on dx {} dy {} dz {}",
                               m_gsd, dx, dy, dz)

   // Compute flying height
   csm::EcefCoord sensorPos = getSensorPosition(0.0);
   dx = sensorPos.x - m_referencePointXyz.x;
   dy = sensorPos.y - m_referencePointXyz.y;
   dz = sensorPos.z - m_referencePointXyz.z;
   m_flyingHeight = sqrt(dx*dx + dy*dy + dz*dz);
   MESSAGE_LOG("updateState: flight height set to {}"
                              "based on dx {} dy {} dz {}",
                               m_flyingHeight, dx, dy, dz)

   // Compute half swath
   m_halfSwath = m_gsd * m_nSamples / 2.0;
   MESSAGE_LOG("updateState: half swath set to {}",
                               m_halfSwath)

   // Compute half time duration
   double fullImageTime = m_intTimeStartTimes.back() - m_intTimeStartTimes.front()
                          + m_intTimes.back() * (m_nLines - m_intTimeLines.back());
   m_halfTime = fullImageTime / 2.0;
   MESSAGE_LOG("updateState: half time duration set to {}",
                               m_halfTime)

   // Parameter covariance, hardcoded accuracy values
   // hardcoded ~1 pixel accuracy values
   int num_params = NUM_PARAMETERS;
   double positionVariance = m_gsd * m_gsd;
   // parameter time is scaled to [0, 2]
   // so divide by 2 for velocities and 4 for accelerations
   double velocityVariance = positionVariance / 2.0;
   double accelerationVariance = positionVariance / 4.0;
   m_covariance.assign(num_params * num_params, 0.0);

   // Set position variances
   m_covariance[0] = positionVariance;
   m_covariance[num_params + 1] = positionVariance;
   m_covariance[2 * num_params + 2] = positionVariance;
   m_covariance[3 * num_params + 3] = velocityVariance;
   m_covariance[4 * num_params + 4] = velocityVariance;
   m_covariance[5 * num_params + 5] = velocityVariance;

   // Set orientation variances
   m_covariance[6 * num_params + 6] = positionVariance;
   m_covariance[7 * num_params + 7] = positionVariance;
   m_covariance[8 * num_params + 8] = positionVariance;
   m_covariance[9 * num_params + 9] = velocityVariance;
   m_covariance[10 * num_params + 10] = velocityVariance;
   m_covariance[11 * num_params + 11] = velocityVariance;
   m_covariance[12 * num_params + 12] = accelerationVariance;
   m_covariance[13 * num_params + 13] = accelerationVariance;
   m_covariance[14 * num_params + 14] = accelerationVariance;

   // Set focal length variance
   m_covariance[15 * num_params + 15] = positionVariance;
}


//---------------------------------------------------------------------------
// Core Photogrammetry
//---------------------------------------------------------------------------

//***************************************************************************
// UsgsAstroLsSensorModel::groundToImage
//***************************************************************************
csm::ImageCoord UsgsAstroLsSensorModel::groundToImage(
   const csm::EcefCoord& ground_pt,
   double                desired_precision,
   double*               achieved_precision,
   csm::WarningList*     warnings) const
{

  MESSAGE_LOG("Computing groundToImage(No adjustments) for {}, {}, {}, with desired precision {}",
              ground_pt.x, ground_pt.y, ground_pt.z, desired_precision);

   // The public interface invokes the private interface with no adjustments.
   return groundToImage(
      ground_pt, _no_adjustment,
      desired_precision, achieved_precision, warnings);
}

//***************************************************************************
// UsgsAstroLsSensorModel::groundToImage (internal version)
//***************************************************************************
csm::ImageCoord UsgsAstroLsSensorModel::groundToImage(
   const csm::EcefCoord& groundPt,
   const std::vector<double>& adj,
   double                desiredPrecision,
   double*               achievedPrecision,
   csm::WarningList*     warnings) const
{
   // Search for the line, sample coordinate that viewed a given ground point.
   // This method first uses a linear approximation to get an initial point.
   // Then the detector offset for the line is continuously computed and
   // applied to the line until we achieve the desired precision.

   csm::ImageCoord approxPt;
   computeLinearApproximation(groundPt, approxPt);

   std::vector<double> detectorView;
   double detectorLine = m_nLines;
   double detectorSample = 0;
   double count = 0;
   double timei;

   while(abs(detectorLine) > desiredPrecision && ++count < 15) {
     timei = getImageTime(approxPt);
     detectorView = computeDetectorView(timei, groundPt, adj);

     // Convert to detector line
     detectorLine = m_iTransL[0]
                  + m_iTransL[1] * detectorView[0]
                  + m_iTransL[2] * detectorView[1]
                  + m_detectorLineOrigin - m_startingDetectorLine;
     detectorLine /= m_detectorLineSumming;

     // Convert to image line
     approxPt.line += detectorLine;
   }

   timei = getImageTime(approxPt);
   detectorView = computeDetectorView(timei, groundPt, adj);

   // Invert distortion
   double distortedFocalX, distortedFocalY;
   applyDistortion(detectorView[0], detectorView[1], distortedFocalX, distortedFocalY,
                   m_opticalDistCoeffs, m_distortionType, desiredPrecision);

   // Convert to detector line and sample
   detectorLine = m_iTransL[0]
                + m_iTransL[1] * distortedFocalX
                + m_iTransL[2] * distortedFocalY;
   detectorSample = m_iTransS[0]
                + m_iTransS[1] * distortedFocalX
                + m_iTransS[2] * distortedFocalY;
   // Convert to image sample line
   double finalUpdate = (detectorLine + m_detectorLineOrigin - m_startingDetectorLine)
                      / m_detectorLineSumming;
   approxPt.line += finalUpdate;
   approxPt.samp = (detectorSample + m_detectorSampleOrigin - m_startingDetectorSample)
                 / m_detectorSampleSumming;

   double precision = detectorLine + m_detectorLineOrigin - m_startingDetectorLine;
   if (achievedPrecision) {
     *achievedPrecision = finalUpdate;
   }

   MESSAGE_LOG("groundToImage: image line sample {} {}",
                                approxPt.line, approxPt.samp)

   if (warnings && (desiredPrecision > 0.0) && (abs(finalUpdate) > desiredPrecision))
   {
      warnings->push_back(
         csm::Warning(
            csm::Warning::PRECISION_NOT_MET,
            "Desired precision not achieved.",
            "UsgsAstroLsSensorModel::groundToImage()"));
   }

   return approxPt;
}

//***************************************************************************
// UsgsAstroLsSensorModel::groundToImage
//***************************************************************************
csm::ImageCoordCovar UsgsAstroLsSensorModel::groundToImage(
   const csm::EcefCoordCovar& groundPt,
   double  desired_precision,
   double* achieved_precision,
   csm::WarningList* warnings) const
{
  MESSAGE_LOG("Computing groundToImage(Covar) for {}, {}, {}, with desired precision {}",
                groundPt.x, groundPt.y, groundPt.z, desired_precision);
   // Ground to image with error propagation
   // Compute corresponding image point
   csm::EcefCoord gp;
   gp.x = groundPt.x;
   gp.y = groundPt.y;
   gp.z = groundPt.z;

   csm::ImageCoord ip = groundToImage(
      gp, desired_precision, achieved_precision, warnings);
   csm::ImageCoordCovar result(ip.line, ip.samp);

   // Compute partials ls wrt XYZ
   std::vector<double> prt(6, 0.0);
   prt = computeGroundPartials(groundPt);

   // Error propagation
   double ltx, lty, ltz;
   double stx, sty, stz;
   ltx =
      prt[0] * groundPt.covariance[0] +
      prt[1] * groundPt.covariance[3] +
      prt[2] * groundPt.covariance[6];
   lty =
      prt[0] * groundPt.covariance[1] +
      prt[1] * groundPt.covariance[4] +
      prt[2] * groundPt.covariance[7];
   ltz =
      prt[0] * groundPt.covariance[2] +
      prt[1] * groundPt.covariance[5] +
      prt[2] * groundPt.covariance[8];
   stx =
      prt[3] * groundPt.covariance[0] +
      prt[4] * groundPt.covariance[3] +
      prt[5] * groundPt.covariance[6];
   sty =
      prt[3] * groundPt.covariance[1] +
      prt[4] * groundPt.covariance[4] +
      prt[5] * groundPt.covariance[7];
   stz =
      prt[3] * groundPt.covariance[2] +
      prt[4] * groundPt.covariance[5] +
      prt[5] * groundPt.covariance[8];

   double gp_cov[4]; // Input gp cov in image space
   gp_cov[0] = ltx * prt[0] + lty * prt[1] + ltz * prt[2];
   gp_cov[1] = ltx * prt[3] + lty * prt[4] + ltz * prt[5];
   gp_cov[2] = stx * prt[0] + sty * prt[1] + stz * prt[2];
   gp_cov[3] = stx * prt[3] + sty * prt[4] + stz * prt[5];

   std::vector<double> unmodeled_cov = getUnmodeledError(ip);
   double sensor_cov[4]; // sensor cov in image space
   determineSensorCovarianceInImageSpace(gp, sensor_cov);

   result.covariance[0] = gp_cov[0] + unmodeled_cov[0] + sensor_cov[0];
   result.covariance[1] = gp_cov[1] + unmodeled_cov[1] + sensor_cov[1];
   result.covariance[2] = gp_cov[2] + unmodeled_cov[2] + sensor_cov[2];
   result.covariance[3] = gp_cov[3] + unmodeled_cov[3] + sensor_cov[3];

   return result;
}

//***************************************************************************
// UsgsAstroLsSensorModel::imageToGround
//***************************************************************************
csm::EcefCoord UsgsAstroLsSensorModel::imageToGround(
   const csm::ImageCoord& image_pt,
   double height,
   double desired_precision,
   double* achieved_precision,
   csm::WarningList* warnings) const
{
   MESSAGE_LOG("Computing imageToGround for {}, {}, {}, with desired precision {}",
               image_pt.line, image_pt.samp, height, desired_precision);
   double xc, yc, zc;
   double vx, vy, vz;
   double xl, yl, zl;
   double dxl, dyl, dzl;
   losToEcf(
      image_pt.line, image_pt.samp, _no_adjustment,
      xc, yc, zc, vx, vy, vz, xl, yl, zl);

   double aPrec;
   double x, y, z;
   losEllipsoidIntersect(
      height, xc, yc, zc, xl, yl, zl, x, y, z, aPrec, desired_precision);

   if (achieved_precision)
      *achieved_precision = aPrec;

   if (warnings && (desired_precision > 0.0) && (aPrec > desired_precision))
   {
      warnings->push_back(
         csm::Warning(
            csm::Warning::PRECISION_NOT_MET,
            "Desired precision not achieved.",
            "UsgsAstroLsSensorModel::imageToGround()"));
   }

/*
    MESSAGE_LOG("imageToGround for {} {} {} achieved precision {}",
                                image_pt.line, image_pt.samp, height, achieved_precision)
*/

   return csm::EcefCoord(x, y, z);
}

//***************************************************************************
// UsgsAstroLineScannerSensorModel::determineSensorCovarianceInImageSpace
//***************************************************************************
void UsgsAstroLsSensorModel::determineSensorCovarianceInImageSpace(
   csm::EcefCoord &gp,
   double         sensor_cov[4] ) const
{
   MESSAGE_LOG("Calculating determineSensorCovarianceInImageSpace for {} {} {}",
                              gp.x, gp.y, gp.z)


   int i, j, totalAdjParams;
   totalAdjParams = getNumParameters();

   std::vector<csm::RasterGM::SensorPartials> sensor_partials = computeAllSensorPartials(gp);

   sensor_cov[0] = 0.0;
   sensor_cov[1] = 0.0;
   sensor_cov[2] = 0.0;
   sensor_cov[3] = 0.0;

   for (i = 0; i < totalAdjParams; i++)
   {
      for (j = 0; j < totalAdjParams; j++)
      {
         sensor_cov[0] += sensor_partials[i].first  * getParameterCovariance(i, j) * sensor_partials[j].first;
         sensor_cov[1] += sensor_partials[i].second * getParameterCovariance(i, j) * sensor_partials[j].first;
         sensor_cov[2] += sensor_partials[i].first  * getParameterCovariance(i, j) * sensor_partials[j].second;
         sensor_cov[3] += sensor_partials[i].second * getParameterCovariance(i, j) * sensor_partials[j].second;
      }
   }
}


//***************************************************************************
// UsgsAstroLsSensorModel::imageToGround
//***************************************************************************
csm::EcefCoordCovar UsgsAstroLsSensorModel::imageToGround(
   const csm::ImageCoordCovar& image_pt,
   double height,
   double heightVariance,
   double desired_precision,
   double* achieved_precision,
   csm::WarningList* warnings) const
{
  MESSAGE_LOG("Calculating imageToGround (with error propagation) for {}, {}, {} with height varinace {} and desired precision {}",
                              image_pt.line, image_pt.samp, height, heightVariance, desired_precision)
   // Image to ground with error propagation
   // Use numerical partials

   const double DELTA_IMAGE = 1.0;
   const double DELTA_GROUND = m_gsd;
   csm::ImageCoord ip(image_pt.line, image_pt.samp);

   csm::EcefCoord gp = imageToGround(
      ip, height, desired_precision, achieved_precision, warnings);

   // Compute numerical partials xyz wrt to lsh
   ip.line = image_pt.line + DELTA_IMAGE;
   ip.samp = image_pt.samp;
   csm::EcefCoord gpl = imageToGround(ip, height, desired_precision);
   double xpl = (gpl.x - gp.x) / DELTA_IMAGE;
   double ypl = (gpl.y - gp.y) / DELTA_IMAGE;
   double zpl = (gpl.z - gp.z) / DELTA_IMAGE;

   ip.line = image_pt.line;
   ip.samp = image_pt.samp + DELTA_IMAGE;
   csm::EcefCoord gps = imageToGround(ip, height, desired_precision);
   double xps = (gps.x - gp.x) / DELTA_IMAGE;
   double yps = (gps.y - gp.y) / DELTA_IMAGE;
   double zps = (gps.z - gp.z) / DELTA_IMAGE;

   ip.line = image_pt.line;
   ip.samp = image_pt.samp; // +DELTA_IMAGE;
   csm::EcefCoord gph = imageToGround(ip, height + DELTA_GROUND, desired_precision);
   double xph = (gph.x - gp.x) / DELTA_GROUND;
   double yph = (gph.y - gp.y) / DELTA_GROUND;
   double zph = (gph.z - gp.z) / DELTA_GROUND;

   // Convert sensor covariance to image space
   double sCov[4];
   determineSensorCovarianceInImageSpace(gp, sCov);

   std::vector<double> unmod = getUnmodeledError(image_pt);

   double iCov[4];
   iCov[0] = image_pt.covariance[0] + sCov[0] + unmod[0];
   iCov[1] = image_pt.covariance[1] + sCov[1] + unmod[1];
   iCov[2] = image_pt.covariance[2] + sCov[2] + unmod[2];
   iCov[3] = image_pt.covariance[3] + sCov[3] + unmod[3];

   // Temporary matrix product
   double t00, t01, t02, t10, t11, t12, t20, t21, t22;
   t00 = xpl * iCov[0] + xps * iCov[2];
   t01 = xpl * iCov[1] + xps * iCov[3];
   t02 = xph * heightVariance;
   t10 = ypl * iCov[0] + yps * iCov[2];
   t11 = ypl * iCov[1] + yps * iCov[3];
   t12 = yph * heightVariance;
   t20 = zpl * iCov[0] + zps * iCov[2];
   t21 = zpl * iCov[1] + zps * iCov[3];
   t22 = zph * heightVariance;

   // Ground covariance
   csm::EcefCoordCovar result;
   result.x = gp.x;
   result.y = gp.y;
   result.z = gp.z;

   result.covariance[0] = t00 * xpl + t01 * xps + t02 * xph;
   result.covariance[1] = t00 * ypl + t01 * yps + t02 * yph;
   result.covariance[2] = t00 * zpl + t01 * zps + t02 * zph;
   result.covariance[3] = t10 * xpl + t11 * xps + t12 * xph;
   result.covariance[4] = t10 * ypl + t11 * yps + t12 * yph;
   result.covariance[5] = t10 * zpl + t11 * zps + t12 * zph;
   result.covariance[6] = t20 * xpl + t21 * xps + t22 * xph;
   result.covariance[7] = t20 * ypl + t21 * yps + t22 * yph;
   result.covariance[8] = t20 * zpl + t21 * zps + t22 * zph;

   return result;
}

//***************************************************************************
// UsgsAstroLsSensorModel::imageToProximateImagingLocus
//***************************************************************************
csm::EcefLocus UsgsAstroLsSensorModel::imageToProximateImagingLocus(
   const csm::ImageCoord& image_pt,
   const csm::EcefCoord& ground_pt,
   double desired_precision,
   double* achieved_precision,
   csm::WarningList* warnings) const
{

  MESSAGE_LOG("Computing imageToProximateImagingLocus (ground {}, {}, {}) for image point {}, {} with desired precision {}",
                              ground_pt.x, ground_pt.y, ground_pt.z, image_pt.line, image_pt.samp, desired_precision);

   // Object ray unit direction near given ground location
   const double DELTA_GROUND = m_gsd;

   double x = ground_pt.x;
   double y = ground_pt.y;
   double z = ground_pt.z;

   // Elevation at input ground point
   double height = computeEllipsoidElevation(
         x, y, z,
         m_majorAxis, m_minorAxis, desired_precision);

   // Ground point on object ray with the same elevation
   csm::EcefCoord gp1 = imageToGround(
      image_pt, height, desired_precision, achieved_precision);

   // Vector between 2 ground points above
   double dx1 = x - gp1.x;
   double dy1 = y - gp1.y;
   double dz1 = z - gp1.z;

   // Unit vector along object ray
   csm::EcefCoord gp2 = imageToGround(
      image_pt, height - DELTA_GROUND, desired_precision, achieved_precision);
   double dx2 = gp2.x - gp1.x;
   double dy2 = gp2.y - gp1.y;
   double dz2 = gp2.z - gp1.z;
   double mag2 = sqrt(dx2 * dx2 + dy2 * dy2 + dz2 * dz2);
   dx2 /= mag2;
   dy2 /= mag2;
   dz2 /= mag2;

   // Point on object ray perpendicular to input point

   // Locus
   csm::EcefLocus locus;
   double scale = dx1 * dx2 + dy1 * dy2 + dz1 * dz2;
   gp2.x = gp1.x + scale * dx2;
   gp2.y = gp1.y + scale * dy2;
   gp2.z = gp1.z + scale * dz2;

   double hLocus = computeEllipsoidElevation(
         gp2.x, gp2.y, gp2.z,
         m_majorAxis, m_minorAxis, desired_precision);
   locus.point = imageToGround(
         image_pt, hLocus, desired_precision, achieved_precision, warnings);

   locus.direction.x = dx2;
   locus.direction.y = dy2;
   locus.direction.z = dz2;

   return locus;
}

//***************************************************************************
// UsgsAstroLsSensorModel::imageToRemoteImagingLocus
//***************************************************************************
csm::EcefLocus UsgsAstroLsSensorModel::imageToRemoteImagingLocus(
   const csm::ImageCoord& image_pt,
   double desired_precision,
   double* achieved_precision,
   csm::WarningList* warnings) const
{

  MESSAGE_LOG("Calculating imageToRemoteImagingLocus for point {}, {} with desired precision {}",
                              image_pt.line, image_pt.samp, desired_precision)

  double vx, vy, vz;
  csm::EcefLocus locus;
  losToEcf(
    image_pt.line, image_pt.samp, _no_adjustment,
    locus.point.x, locus.point.y, locus.point.z,
    vx, vy, vz,
    locus.direction.x, locus.direction.y, locus.direction.z);
  // losToEcf computes the negative look vector, so negate it
  locus.direction.x = -locus.direction.x;
  locus.direction.y = -locus.direction.y;
  locus.direction.z = -locus.direction.z;
  return locus;
}

//---------------------------------------------------------------------------
// Uncertainty Propagation
//---------------------------------------------------------------------------

//***************************************************************************
// UsgsAstroLsSensorModel::computeGroundPartials
//***************************************************************************
std::vector<double> UsgsAstroLsSensorModel::computeGroundPartials(
   const csm::EcefCoord& ground_pt) const
{

   MESSAGE_LOG("Computing computeGroundPartials for point {}, {}, {}",
                                ground_pt.x, ground_pt.y, ground_pt.z)

   double GND_DELTA = m_gsd;
   // Partial of line, sample wrt X, Y, Z
   double x = ground_pt.x;
   double y = ground_pt.y;
   double z = ground_pt.z;

   csm::ImageCoord ipB = groundToImage(ground_pt);
   csm::ImageCoord ipX = groundToImage(csm::EcefCoord(x + GND_DELTA, y, z));
   csm::ImageCoord ipY = groundToImage(csm::EcefCoord(x, y + GND_DELTA, z));
   csm::ImageCoord ipZ = groundToImage(csm::EcefCoord(x, y, z + GND_DELTA));

   std::vector<double> partials(6, 0.0);
   partials[0] = (ipX.line - ipB.line) / GND_DELTA;
   partials[3] = (ipX.samp - ipB.samp) / GND_DELTA;
   partials[1] = (ipY.line - ipB.line) / GND_DELTA;
   partials[4] = (ipY.samp - ipB.samp) / GND_DELTA;
   partials[2] = (ipZ.line - ipB.line) / GND_DELTA;
   partials[5] = (ipZ.samp - ipB.samp) / GND_DELTA;

   return partials;
}


//***************************************************************************
// UsgsAstroLsSensorModel::computeSensorPartials
//***************************************************************************
csm::RasterGM::SensorPartials UsgsAstroLsSensorModel::computeSensorPartials(
   int index,
   const csm::EcefCoord& ground_pt,
   double  desired_precision,
   double* achieved_precision,
   csm::WarningList* warnings) const
{

  MESSAGE_LOG("Calculating computeSensorPartials for ground point {}, {}, {} with desired precision {}",
                              ground_pt.x, ground_pt.y, ground_pt.z, desired_precision)

   // Compute image coordinate first
   csm::ImageCoord img_pt = groundToImage(
      ground_pt, desired_precision, achieved_precision);

   // Call overloaded function
   return computeSensorPartials(
      index, img_pt, ground_pt, desired_precision, achieved_precision, warnings);
}

//***************************************************************************
// UsgsAstroLsSensorModel::computeSensorPartials
//***************************************************************************
csm::RasterGM::SensorPartials UsgsAstroLsSensorModel::computeSensorPartials(
   int                    index,
   const csm::ImageCoord& image_pt,
   const csm::EcefCoord&  ground_pt,
   double                 desired_precision,
   double*                achieved_precision,
   csm::WarningList*      warnings) const
{

  MESSAGE_LOG("Calculating computeSensorPartials (with image points {}, {}) for ground point {}, {}, {} with desired precision {}",
                              image_pt.line, image_pt.samp, ground_pt.x, ground_pt.y, ground_pt.z, desired_precision)

   // Compute numerical partials ls wrt specific parameter

   const double DELTA = m_gsd;
   std::vector<double> adj(UsgsAstroLsSensorModel::NUM_PARAMETERS, 0.0);
   adj[index] = DELTA;

   csm::ImageCoord img1 = groundToImage(
      ground_pt, adj, desired_precision, achieved_precision, warnings);

   double line_partial = (img1.line - image_pt.line) / DELTA;
   double sample_partial = (img1.samp - image_pt.samp) / DELTA;

   return csm::RasterGM::SensorPartials(line_partial, sample_partial);
}

//***************************************************************************
// UsgsAstroLsSensorModel::computeAllSensorPartials
//***************************************************************************
std::vector<csm::RasterGM::SensorPartials>
UsgsAstroLsSensorModel::computeAllSensorPartials(
   const csm::EcefCoord& ground_pt,
   csm::param::Set       pSet,
   double                desired_precision,
   double*               achieved_precision,
   csm::WarningList*     warnings) const
{
  MESSAGE_LOG("Computing computeAllSensorPartials for ground point {}, {}, {} with desired precision {}",
                              ground_pt.x, ground_pt.y, ground_pt.z, desired_precision)
   csm::ImageCoord image_pt = groundToImage(
      ground_pt, desired_precision, achieved_precision, warnings);

   return computeAllSensorPartials(
      image_pt, ground_pt, pSet, desired_precision, achieved_precision, warnings);
}

//***************************************************************************
// UsgsAstroLsSensorModel::computeAllSensorPartials
//***************************************************************************
std::vector<csm::RasterGM::SensorPartials>
UsgsAstroLsSensorModel::computeAllSensorPartials(
   const csm::ImageCoord& image_pt,
   const csm::EcefCoord&  ground_pt,
   csm::param::Set        pSet,
   double                 desired_precision,
   double*                achieved_precision,
   csm::WarningList*      warnings) const
{

   MESSAGE_LOG("Computing computeAllSensorPartials for image {} {} and ground {}, {}, {} with desired precision {}",
                                image_pt.line, image_pt.samp, ground_pt.x, ground_pt.y, ground_pt.z, desired_precision)

   std::vector<int> indices = getParameterSetIndices(pSet);
   size_t num = indices.size();
   std::vector<csm::RasterGM::SensorPartials> partials;
   for (int index = 0; index < num; index++)
   {
      partials.push_back(
         computeSensorPartials(
            indices[index], image_pt, ground_pt,
            desired_precision, achieved_precision, warnings));
   }
   return partials;
}

//***************************************************************************
// UsgsAstroLsSensorModel::getParameterCovariance
//***************************************************************************
double UsgsAstroLsSensorModel::getParameterCovariance(
   int index1,
   int index2) const
{

   int index = UsgsAstroLsSensorModel::NUM_PARAMETERS * index1 + index2;

   MESSAGE_LOG("getParameterCovariance for {} {} is {}",
                                index1, index2, m_covariance[index])

   return m_covariance[index];
}

//***************************************************************************
// UsgsAstroLsSensorModel::setParameterCovariance
//***************************************************************************
void UsgsAstroLsSensorModel::setParameterCovariance(
   int index1,
   int index2,
   double covariance)
{
   int index = UsgsAstroLsSensorModel::NUM_PARAMETERS * index1 + index2;

   MESSAGE_LOG("setParameterCovariance for {} {} is {}",
                                index1, index2, m_covariance[index])

   m_covariance[index] = covariance;
}

//---------------------------------------------------------------------------
// Time and Trajectory
//---------------------------------------------------------------------------

//***************************************************************************
// UsgsAstroLsSensorModel::getTrajectoryIdentifier
//***************************************************************************
std::string UsgsAstroLsSensorModel::getTrajectoryIdentifier() const
{
   return "UNKNOWN";
}

//***************************************************************************
// UsgsAstroLsSensorModel::getReferenceDateAndTime
//***************************************************************************
std::string UsgsAstroLsSensorModel::getReferenceDateAndTime() const
{
    csm::EcefCoord referencePointGround = UsgsAstroLsSensorModel::getReferencePoint();
    csm::ImageCoord referencePointImage = UsgsAstroLsSensorModel::groundToImage(referencePointGround);
    double relativeTime = UsgsAstroLsSensorModel::getImageTime(referencePointImage);
    time_t ephemTime = m_centerEphemerisTime + relativeTime;
    struct tm t = {0};  // Initalize to all 0's
    t.tm_year = 100;  // This is year-1900, so 100 = 2000
    t.tm_mday = 1;
    time_t timeSinceEpoch = mktime(&t);
    time_t finalTime = ephemTime + timeSinceEpoch;
    char buffer [16];
    strftime(buffer, 16, "%Y%m%dT%H%M%S", localtime(&finalTime));
    buffer[15] = '\0';

    return buffer;
}

//***************************************************************************
// UsgsAstroLsSensorModel::getImageTime
//***************************************************************************
double UsgsAstroLsSensorModel::getImageTime(
   const csm::ImageCoord& image_pt) const
{
   double lineFull = image_pt.line;

   auto referenceLineIt = std::upper_bound(m_intTimeLines.begin(),
                                           m_intTimeLines.end(),
                                           lineFull);
   if (referenceLineIt != m_intTimeLines.begin()) {
      --referenceLineIt;
   }
   size_t referenceIndex = std::distance(m_intTimeLines.begin(), referenceLineIt);

   // Adding 0.5 to the line results in center exposure time for a given line
   double time = m_intTimeStartTimes[referenceIndex]
      + m_intTimes[referenceIndex] * (lineFull - m_intTimeLines[referenceIndex] + 0.5);

   MESSAGE_LOG("getImageTime for image line {} is {}",
                         image_pt.line, time)

   return time;
}

//***************************************************************************
// UsgsAstroLsSensorModel::getSensorPosition
//***************************************************************************
csm::EcefCoord UsgsAstroLsSensorModel::getSensorPosition(
   const csm::ImageCoord& imagePt) const
{
   MESSAGE_LOG("getSensorPosition at line {}",
                                imagePt.line)

   return getSensorPosition(getImageTime(imagePt));
}

//***************************************************************************
// UsgsAstroLsSensorModel::getSensorPosition
//***************************************************************************
csm::EcefCoord UsgsAstroLsSensorModel::getSensorPosition(double time) const

{
   double x, y, z, vx, vy, vz;
   getAdjSensorPosVel(time, _no_adjustment, x, y, z, vx, vy, vz);

   MESSAGE_LOG("getSensorPosition at {}",
                                time)

   return csm::EcefCoord(x, y, z);
}

//***************************************************************************
// UsgsAstroLsSensorModel::getSensorVelocity
//***************************************************************************
csm::EcefVector UsgsAstroLsSensorModel::getSensorVelocity(
   const csm::ImageCoord& imagePt) const
{
  MESSAGE_LOG("getSensorVelocity at {}",
                               imagePt.line)
   return getSensorVelocity(getImageTime(imagePt));
}

//***************************************************************************
// UsgsAstroLsSensorModel::getSensorVelocity
//***************************************************************************
csm::EcefVector UsgsAstroLsSensorModel::getSensorVelocity(double time) const
{
   double x, y, z, vx, vy, vz;
   getAdjSensorPosVel(time, _no_adjustment, x, y, z, vx, vy, vz);

   MESSAGE_LOG("getSensorVelocity at {}",
                                time)

   return csm::EcefVector(vx, vy, vz);
}

//---------------------------------------------------------------------------
// Sensor Model Parameters
//---------------------------------------------------------------------------

//***************************************************************************
// UsgsAstroLsSensorModel::setParameterValue
//***************************************************************************
void UsgsAstroLsSensorModel::setParameterValue(int index, double value)
{
   m_currentParameterValue[index] = value;
}

//***************************************************************************
// UsgsAstroLsSensorModel::getParameterValue
//***************************************************************************
double UsgsAstroLsSensorModel::getParameterValue(int index) const
{
   return m_currentParameterValue[index];
}

//***************************************************************************
// UsgsAstroLsSensorModel::getParameterName
//***************************************************************************
std::string UsgsAstroLsSensorModel::getParameterName(int index) const
{
   return PARAMETER_NAME[index];
}

std::string UsgsAstroLsSensorModel::getParameterUnits(int index) const
{
   // All parameters are meters or scaled to meters
   return "m";
}


//***************************************************************************
// UsgsAstroLsSensorModel::getNumParameters
//***************************************************************************
int UsgsAstroLsSensorModel::getNumParameters() const
{
   return UsgsAstroLsSensorModel::NUM_PARAMETERS;
}


//***************************************************************************
// UsgsAstroLsSensorModel::getParameterType
//***************************************************************************
csm::param::Type UsgsAstroLsSensorModel::getParameterType(int index) const
{
   return m_parameterType[index];
}


//***************************************************************************
// UsgsAstroLsSensorModel::setParameterType
//***************************************************************************
void UsgsAstroLsSensorModel::setParameterType(
   int index, csm::param::Type pType)
{
   m_parameterType[index] = pType;
}

//---------------------------------------------------------------------------
// Sensor Model Information
//---------------------------------------------------------------------------

//***************************************************************************
// UsgsAstroLsSensorModel::getPedigree
//***************************************************************************
std::string UsgsAstroLsSensorModel::getPedigree() const
{
   return "USGS_LINE_SCANNER";
}

//***************************************************************************
// UsgsAstroLsSensorModel::getImageIdentifier
//***************************************************************************
std::string UsgsAstroLsSensorModel::getImageIdentifier() const
{
   return m_imageIdentifier;
}

//***************************************************************************
// UsgsAstroLsSensorModel::setImageIdentifier
//***************************************************************************
void UsgsAstroLsSensorModel::setImageIdentifier(
   const std::string& imageId,
   csm::WarningList* warnings)
{
   // Image id should include the suffix without the path name
   m_imageIdentifier = imageId;
}

//***************************************************************************
// UsgsAstroLsSensorModel::getSensorIdentifier
//***************************************************************************
std::string UsgsAstroLsSensorModel::getSensorIdentifier() const
{
   return m_sensorIdentifier;
}

//***************************************************************************
// UsgsAstroLsSensorModel::getPlatformIdentifier
//***************************************************************************
std::string UsgsAstroLsSensorModel::getPlatformIdentifier() const
{
   return m_platformIdentifier;
}

//***************************************************************************
// UsgsAstroLsSensorModel::setReferencePoint
//***************************************************************************
void UsgsAstroLsSensorModel::setReferencePoint(const csm::EcefCoord& ground_pt)
{
   m_referencePointXyz = ground_pt;
}

//***************************************************************************
// UsgsAstroLsSensorModel::getReferencePoint
//***************************************************************************
csm::EcefCoord UsgsAstroLsSensorModel::getReferencePoint() const
{
   // Return ground point at image center
   return m_referencePointXyz;
}

//***************************************************************************
// UsgsAstroLsSensorModel::getSensorModelName
//***************************************************************************
std::string UsgsAstroLsSensorModel::getModelName() const
{
   return UsgsAstroLsSensorModel::_SENSOR_MODEL_NAME;
}

//***************************************************************************
// UsgsAstroLsSensorModel::getImageStart
//***************************************************************************
csm::ImageCoord UsgsAstroLsSensorModel::getImageStart() const
{
   return csm::ImageCoord(0.0, 0.0);
}

//***************************************************************************
// UsgsAstroLsSensorModel::getImageSize
//***************************************************************************
csm::ImageVector UsgsAstroLsSensorModel::getImageSize() const
{
   return csm::ImageVector(m_nLines, m_nSamples);
}

//---------------------------------------------------------------------------
// Sensor Model State
//---------------------------------------------------------------------------
//
// //***************************************************************************
// // UsgsAstroLsSensorModel::getSensorModelState
// //***************************************************************************
// std::string UsgsAstroLsSensorModel::setModelState(std::string stateString) const
// {
//   auto j = json::parse(stateString);
//   int num_params    = NUM_PARAMETERS;
//   int num_paramsSq = num_params * num_params;
//
//   m_imageIdentifier = j["m_imageIdentifier"];
//   m_sensorName = j["m_sensorName"];
//   m_nLines = j["m_nLines"];
//   m_nSamples = j["m_nSamples"];
//   m_platformFlag = j["m_platformFlag"];
//   m_intTimeLines = j["m_intTimeLines"].get<std::vector<double>>();
//   m_intTimeStartTimes = j["m_intTimeStartTimes"].get<std::vector<double>>();
//   m_intTimes = j["m_intTimes"].get<std::vector<double>>();
//   m_startingEphemerisTime = j["m_startingEphemerisTime"];
//   m_centerEphemerisTime = j["m_centerEphemerisTime"];
//   m_detectorSampleSumming = j["m_detectorSampleSumming"];
//   m_startingDetectorSample = j["m_startingDetectorSample"];
//   m_ikCode = j["m_ikCode"];
//   m_focalLength = j["m_focalLength"];
//   m_isisZDirection = j["m_isisZDirection"];
//   for (int i = 0; i < 3; i++) {
//     m_opticalDistCoef[i] = j["m_opticalDistCoef"][i];
//     m_iTransS[i] = j["m_iTransS"][i];
//     m_iTransL[i] = j["m_iTransL"][i];
//   }
//   m_detectorSampleOrigin = j["m_detectorSampleOrigin"];
//   m_detectorLineOrigin = j["m_detectorLineOrigin"];
//   for (int i = 0; i < 9; i++) {
//       m_mountingMatrix[i] = j["m_mountingMatrix"][i];
//   }
//   m_majorAxis = j["m_majorAxis"];
//   m_minorAxis = j["m_minorAxis"];
//   m_platformIdentifier = j["m_platformIdentifier"];
//   m_sensorIdentifier = j["m_sensorIdentifier"];
//   m_minElevation = j["m_minElevation"];
//   m_maxElevation = j["m_maxElevation"];
//   m_dtEphem = j["m_dtEphem"];
//   m_t0Ephem = j["m_t0Ephem"];
//   m_dtQuat = j["m_dtQuat"];
//   m_t0Quat = j["m_t0Quat"];
//   m_numPositions = j["m_numPositions"];
//   m_numQuaternions = j["m_numQuaternions"];
//   m_referencePointXyz.x = j["m_referencePointXyz"][0];
//   m_referencePointXyz.y = j["m_referencePointXyz"][1];
//   m_referencePointXyz.z = j["m_referencePointXyz"][2];
//   m_gsd = j["m_gsd"];
//   m_flyingHeight = j["m_flyingHeight"];
//   m_halfSwath = j["m_halfSwath"];
//   m_halfTime = j["m_halfTime"];
//   // Vector = is overloaded so explicit get with type required.
//   m_positions = j["m_positions"].get<std::vector<double>>();
//   m_velocities = j["m_velocities"].get<std::vector<double>>();
//   m_quaternions = j["m_quaternions"].get<std::vector<double>>();
//   m_currentParameterValue = j["m_currentParameterValue"].get<std::vector<double>>();
//   m_covariance = j["m_covariance"].get<std::vector<double>>();
//
//   for (int i = 0; i < num_params; i++) {
//     for (int k = 0; k < NUM_PARAM_TYPES; k++) {
//       if (j["m_parameterType"][i] == PARAM_STRING_ALL[k]) {
//         m_parameterType[i] = PARAM_CHAR_ALL[k];
//         break;
//     }
//    }
//   }
//
// }

//---------------------------------------------------------------------------
//  Monoscopic Mensuration
//---------------------------------------------------------------------------

//***************************************************************************
// UsgsAstroLsSensorModel::getValidHeightRange
//***************************************************************************
std::pair<double, double> UsgsAstroLsSensorModel::getValidHeightRange() const
{
   return std::pair<double, double>(m_minElevation, m_maxElevation);
}

//***************************************************************************
// UsgsAstroLsSensorModel::getValidImageRange
//***************************************************************************
std::pair<csm::ImageCoord, csm::ImageCoord>
UsgsAstroLsSensorModel::getValidImageRange() const
{
   return std::pair<csm::ImageCoord, csm::ImageCoord>(
      csm::ImageCoord(0.0, 0.0),
      csm::ImageCoord(m_nLines, m_nSamples)); // Technically nl and ns are outside the image in a zero based system.
}

//***************************************************************************
// UsgsAstroLsSensorModel::getIlluminationDirection
//***************************************************************************
csm::EcefVector UsgsAstroLsSensorModel::getIlluminationDirection(
   const csm::EcefCoord& groundPt) const
{
  MESSAGE_LOG("Accessing illumination direction of ground point"
              "{} {} {}.",
              groundPt.x, groundPt.y, groundPt.z);

  csm::EcefVector sunPosition = getSunPosition(getImageTime(groundToImage(groundPt)));
  csm::EcefVector illuminationDirection = csm::EcefVector(groundPt.x - sunPosition.x,
                                                          groundPt.y - sunPosition.y,
                                                          groundPt.z - sunPosition.z);

  double scale = sqrt(illuminationDirection.x * illuminationDirection.x +
                      illuminationDirection.y * illuminationDirection.y +
                      illuminationDirection.z * illuminationDirection.z);

  illuminationDirection.x /= scale;
  illuminationDirection.y /= scale;
  illuminationDirection.z /= scale;
  return illuminationDirection;
}

//---------------------------------------------------------------------------
//  Error Correction
//---------------------------------------------------------------------------

//***************************************************************************
// UsgsAstroLsSensorModel::getNumGeometricCorrectionSwitches
//***************************************************************************
int UsgsAstroLsSensorModel::getNumGeometricCorrectionSwitches() const
{
   return 0;
}

//***************************************************************************
// UsgsAstroLsSensorModel::getGeometricCorrectionName
//***************************************************************************
std::string UsgsAstroLsSensorModel::getGeometricCorrectionName(int index) const
{
  MESSAGE_LOG("Accessing name of geometric correction switch {}. "
              "Geometric correction switches are not supported, throwing exception",
              index);
   // Since there are no geometric corrections, all indices are out of range
   throw csm::Error(
      csm::Error::INDEX_OUT_OF_RANGE,
      "Index is out of range.",
      "UsgsAstroLsSensorModel::getGeometricCorrectionName");
}

//***************************************************************************
// UsgsAstroLsSensorModel::setGeometricCorrectionSwitch
//***************************************************************************
void UsgsAstroLsSensorModel::setGeometricCorrectionSwitch(
   int  index,
   bool value,
   csm::param::Type pType)

{
   MESSAGE_LOG("Setting geometric correction switch {} to {} "
               "with parameter type {}. "
               "Geometric correction switches are not supported, throwing exception",
               index, value, pType);
   // Since there are no geometric corrections, all indices are out of range
   throw csm::Error(
      csm::Error::INDEX_OUT_OF_RANGE,
      "Index is out of range.",
      "UsgsAstroLsSensorModel::setGeometricCorrectionSwitch");
}

//***************************************************************************
// UsgsAstroLsSensorModel::getGeometricCorrectionSwitch
//***************************************************************************
bool UsgsAstroLsSensorModel::getGeometricCorrectionSwitch(int index) const
{
   MESSAGE_LOG("Accessing value of geometric correction switch {}. "
               "Geometric correction switches are not supported, throwing exception",
               index);
   // Since there are no geometric corrections, all indices are out of range
   throw csm::Error(
      csm::Error::INDEX_OUT_OF_RANGE,
      "Index is out of range.",
      "UsgsAstroLsSensorModel::getGeometricCorrectionSwitch");
}

//***************************************************************************
// UsgsAstroLsSensorModel::getCrossCovarianceMatrix
//***************************************************************************
std::vector<double> UsgsAstroLsSensorModel::getCrossCovarianceMatrix(
   const csm::GeometricModel& comparisonModel,
   csm::param::Set            pSet,
   const csm::GeometricModel::GeometricModelList& otherModels) const
{
   // Return covariance matrix
   if (&comparisonModel == this) {
     std::vector<int> paramIndices = getParameterSetIndices(pSet);
     int numParams = paramIndices.size();
     std::vector<double> covariances(numParams * numParams, 0.0);
     for (int i = 0; i < numParams; i++) {
       for (int j = 0; j < numParams; j++) {
         covariances[i * numParams + j] = getParameterCovariance(paramIndices[i], paramIndices[j]);
       }
     }
     return covariances;
   }
   // No correlation between models.
   const std::vector<int>& indices = getParameterSetIndices(pSet);
   size_t num_rows = indices.size();
   const std::vector<int>& indices2 = comparisonModel.getParameterSetIndices(pSet);
   size_t num_cols = indices.size();

   return std::vector<double>(num_rows * num_cols, 0.0);
}

//***************************************************************************
// UsgsAstroLineScannerSensorModel::getCorrelationModel
//***************************************************************************
const csm::CorrelationModel&
UsgsAstroLsSensorModel::getCorrelationModel() const
{
   // All Line Scanner images are assumed uncorrelated
   return _no_corr_model;
}

//***************************************************************************
// UsgsAstroLsSensorModel::getUnmodeledCrossCovariance
//***************************************************************************
std::vector<double> UsgsAstroLsSensorModel::getUnmodeledCrossCovariance(
   const csm::ImageCoord& pt1,
   const csm::ImageCoord& pt2) const
{
   // No unmodeled error
   return std::vector<double>(4, 0.0);
}


//***************************************************************************
// UsgsAstroLsSensorModel::getCollectionIdentifier
//***************************************************************************
std::string UsgsAstroLsSensorModel::getCollectionIdentifier() const
{
   return "UNKNOWN";
}

//***************************************************************************
// UsgsAstroLsSensorModel::hasShareableParameters
//***************************************************************************
bool UsgsAstroLsSensorModel::hasShareableParameters() const
{
   // Parameter sharing is not supported for this sensor
   return false;
}

//***************************************************************************
// UsgsAstroLsSensorModel::isParameterShareable
//***************************************************************************
bool UsgsAstroLsSensorModel::isParameterShareable(int index) const
{
   // Parameter sharing is not supported for this sensor
   return false;
}

//***************************************************************************
// UsgsAstroLsSensorModel::getParameterSharingCriteria
//***************************************************************************
csm::SharingCriteria UsgsAstroLsSensorModel::getParameterSharingCriteria(
   int index) const
{
  MESSAGE_LOG("Checking sharing criteria for parameter {}. "
              "Sharing is not supported, throwing exception", index);
   // Parameter sharing is not supported for this sensor,
   // all indices are out of range
   throw csm::Error(
      csm::Error::INDEX_OUT_OF_RANGE,
      "Index out of range.",
      "UsgsAstroLsSensorModel::getParameterSharingCriteria");
}

//***************************************************************************
// UsgsAstroLsSensorModel::getSensorType
//***************************************************************************
std::string UsgsAstroLsSensorModel::getSensorType() const
{
   return CSM_SENSOR_TYPE_EO;
}

//***************************************************************************
// UsgsAstroLsSensorModel::getSensorMode
//***************************************************************************
std::string UsgsAstroLsSensorModel::getSensorMode() const
{
   return CSM_SENSOR_MODE_PB;
}

//***************************************************************************
// UsgsAstroLsSensorModel::getVersion
//***************************************************************************
csm::Version UsgsAstroLsSensorModel::getVersion() const
{
   return csm::Version(1, 0, 0);
}

//***************************************************************************
// UsgsAstroLineScannerSensorModel::getEllipsoid
//***************************************************************************
csm::Ellipsoid UsgsAstroLsSensorModel::getEllipsoid() const
{
   return csm::Ellipsoid(m_majorAxis, m_minorAxis);
}

void UsgsAstroLsSensorModel::setEllipsoid(
   const csm::Ellipsoid &ellipsoid)
{
   m_majorAxis = ellipsoid.getSemiMajorRadius();
   m_minorAxis = ellipsoid.getSemiMinorRadius();
}

//***************************************************************************
// UsgsAstroLineScannerSensorModel::getValue
//***************************************************************************
double UsgsAstroLsSensorModel::getValue(
   int   index,
   const std::vector<double> &adjustments) const
{
   return m_currentParameterValue[index] + adjustments[index];
}


//***************************************************************************
// Functions pulled out of losToEcf and computeViewingPixel
// **************************************************************************
void UsgsAstroLsSensorModel::getQuaternions(const double& time, double q[4]) const{
  int nOrder = 8;
  if (m_platformFlag == 0)
     nOrder = 4;
  int nOrderQuat = nOrder;
  if (m_numQuaternions < 6 && nOrder == 8)
     nOrderQuat = 4;

  MESSAGE_LOG("Calculating getQuaternions for time {} with {}"
                              "order lagrange",
                              time, nOrder)
  lagrangeInterp(
     m_numQuaternions/4, &m_quaternions[0], m_t0Quat, m_dtQuat, time, 4, nOrderQuat, q);
}

//***************************************************************************
// UsgsAstroLineScannerSensorModel::calculateAttitudeCorrection
//***************************************************************************
void UsgsAstroLsSensorModel::calculateAttitudeCorrection(
   const double& time,
   const std::vector<double>& adj,
   double attCorr[9]) const
{
  MESSAGE_LOG("Computing calculateAttitudeCorrection (with adjustment)"
                              "for time {}", time)
  double aTime = time - m_t0Quat;
  double euler[3];
  double nTime = aTime / m_halfTime;
  double nTime2 = nTime * nTime;
  euler[0] =
    (getValue(6, adj) + getValue(9, adj)* nTime + getValue(12, adj)* nTime2) / m_flyingHeight;
  euler[1] =
    (getValue(7, adj) + getValue(10, adj)* nTime + getValue(13, adj)* nTime2) / m_flyingHeight;
  euler[2] =
    (getValue(8, adj) + getValue(11, adj)* nTime + getValue(14, adj)* nTime2) / m_halfSwath;
  MESSAGE_LOG("calculateAttitudeCorrection: euler {} {} {}",
                              euler[0], euler[1], euler[2])

  calculateRotationMatrixFromEuler(euler, attCorr);
}


//***************************************************************************
// UsgsAstroLsSensorModel::losToEcf
//***************************************************************************
void UsgsAstroLsSensorModel::losToEcf(
   const double& line,       // CSM image convention
   const double& sample,     // UL pixel center == (0.5, 0.5)
   const std::vector<double>& adj, // Parameter Adjustments for partials
   double&       xc,         // output sensor x coordinate
   double&       yc,         // output sensor y coordinate
   double&       zc,         // output sensor z coordinate
   double&       vx,         // output sensor x velocity
   double&       vy,         // output sensor y velocity
   double&       vz,         // output sensor z velocity
   double&       bodyLookX,         // output line-of-sight x coordinate
   double&       bodyLookY,         // output line-of-sight y coordinate
   double&       bodyLookZ) const  // output line-of-sight z coordinate
{
   //# private_func_description
   // Computes image ray (look vector) in ecf coordinate system.
   // Compute adjusted sensor position and velocity
   MESSAGE_LOG("Computing losToEcf (with adjustments) for"
                               "line {} sample {}",
                                line, sample)

   double time = getImageTime(csm::ImageCoord(line, sample));
   getAdjSensorPosVel(time, adj, xc, yc, zc, vx, vy, vz);
   // CSM image image convention: UL pixel center == (0.5, 0.5)
   // USGS image convention: UL pixel center == (1.0, 1.0)
   double sampleCSMFull = sample;
   double sampleUSGSFull = sampleCSMFull;

   // Compute distorted image coordinates in mm (sample, line on image (pixels) -> focal plane
   double distortedFocalPlaneX, distortedFocalPlaneY;
   computeDistortedFocalPlaneCoordinates(
         0.0, sampleUSGSFull,
         m_detectorSampleOrigin, m_detectorLineOrigin,
         m_detectorSampleSumming, m_detectorLineSumming,
         m_startingDetectorSample, m_startingDetectorLine,
         m_iTransS, m_iTransL,
         distortedFocalPlaneX, distortedFocalPlaneY);
   MESSAGE_LOG("losToEcf: distorted focal plane coordinate {} {}",
                         distortedFocalPlaneX, distortedFocalPlaneY)

   // Remove lens
   double undistortedFocalPlaneX, undistortedFocalPlaneY;
   removeDistortion(distortedFocalPlaneX, distortedFocalPlaneY,
                    undistortedFocalPlaneX, undistortedFocalPlaneY,
                    m_opticalDistCoeffs,
                    m_distortionType);
   MESSAGE_LOG("losToEcf: undistorted focal plane coordinate {} {}",
                         undistortedFocalPlaneX, undistortedFocalPlaneY)

  // Define imaging ray (look vector) in camera space
   double cameraLook[3];
   createCameraLookVector(undistortedFocalPlaneX, undistortedFocalPlaneY,
                          m_zDirection, m_focalLength * (1 - getValue(15, adj) / m_halfSwath),
                          cameraLook);
   MESSAGE_LOG("losToEcf: uncorrected camera look vector {} {} {}",
                         cameraLook[0], cameraLook[1], cameraLook[2])

   // Apply attitude correction
   double attCorr[9];
   calculateAttitudeCorrection(time, adj, attCorr);

   double correctedCameraLook[3];
   correctedCameraLook[0] = attCorr[0] * cameraLook[0]
                          + attCorr[1] * cameraLook[1]
                          + attCorr[2] * cameraLook[2];
   correctedCameraLook[1] = attCorr[3] * cameraLook[0]
                          + attCorr[4] * cameraLook[1]
                          + attCorr[5] * cameraLook[2];
   correctedCameraLook[2] = attCorr[6] * cameraLook[0]
                          + attCorr[7] * cameraLook[1]
                          + attCorr[8] * cameraLook[2];
   MESSAGE_LOG("losToEcf: corrected camera look vector {} {} {}",
                               correctedCameraLook[0], correctedCameraLook[1],
                               correctedCameraLook[2])
// Rotate the look vector into the body fixed frame from the camera reference frame by applying the rotation matrix from the sensor quaternions
   double quaternions[4];
   getQuaternions(time, quaternions);
   double cameraToBody[9];
   calculateRotationMatrixFromQuaternions(quaternions, cameraToBody);

   bodyLookX = cameraToBody[0] * correctedCameraLook[0]
             + cameraToBody[1] * correctedCameraLook[1]
             + cameraToBody[2] * correctedCameraLook[2];
   bodyLookY = cameraToBody[3] * correctedCameraLook[0]
             + cameraToBody[4] * correctedCameraLook[1]
             + cameraToBody[5] * correctedCameraLook[2];
   bodyLookZ = cameraToBody[6] * correctedCameraLook[0]
             + cameraToBody[7] * correctedCameraLook[1]
             + cameraToBody[8] * correctedCameraLook[2];
   MESSAGE_LOG("losToEcf: body look vector {} {} {}",
                                bodyLookX, bodyLookY, bodyLookZ)

}


//***************************************************************************
// UsgsAstroLsSensorModel::lightAberrationCorr
//**************************************************************************
void UsgsAstroLsSensorModel::lightAberrationCorr(
   const double& vx,
   const double& vy,
   const double& vz,
   const double& xl,
   const double& yl,
   const double& zl,
   double&       dxl,
   double&       dyl,
   double&       dzl) const
{
   MESSAGE_LOG("Computing lightAberrationCorr for camera velocity"
                               "{} {} {} and image ray {} {} {}",
                                vx, vy, vz, xl, yl, zl)
   //# func_description
   //  Computes light aberration correction vector

   // Compute angle between the image ray and the velocity vector

   double dotP = xl * vx + yl * vy + zl * vz;
   double losMag = sqrt(xl * xl + yl * yl + zl * zl);
   double velocityMag = sqrt(vx *  vx + vy * vy + vz * vz);
   double cosThetap = dotP / (losMag * velocityMag);
   double sinThetap = sqrt(1.0 - cosThetap * cosThetap);

   // Image ray is parallel to the velocity vector

   if (1.0 == fabs(cosThetap))
   {
      dxl = 0.0;
      dyl = 0.0;
      dzl = 0.0;
      MESSAGE_LOG("lightAberrationCorr: image ray is parallel"
                                  "to velocity vector")
   }

   // Compute the angle between the corrected image ray and spacecraft
   // velocity.  This key equation is derived using Lorentz transform.

   double speedOfLight = 299792458.0;   // meters per second
   double beta = velocityMag / speedOfLight;
   double cosTheta = (beta - cosThetap) / (beta * cosThetap - 1.0);
   double sinTheta = sqrt(1.0 - cosTheta * cosTheta);

   // Compute line-of-sight correction

   double cfac = ((cosTheta * sinThetap
      - sinTheta * cosThetap) * losMag)
      / (sinTheta * velocityMag);
   dxl = cfac * vx;
   dyl = cfac * vy;
   dzl = cfac * vz;
   MESSAGE_LOG("lightAberrationCorr: light of sight correction"
                               "{} {} {}", dxl, dyl, dzl)
}

//***************************************************************************
// UsgsAstroLsSensorModel::losEllipsoidIntersect
//**************************************************************************
void UsgsAstroLsSensorModel::losEllipsoidIntersect(
   const double& height,
   const double& xc,
   const double& yc,
   const double& zc,
   const double& xl,
   const double& yl,
   const double& zl,
   double&       x,
   double&       y,
   double&       z,
   double&       achieved_precision,
   const double& desired_precision) const
{
   MESSAGE_LOG("Computing losEllipsoidIntersect for camera position "
                               "{} {} {} looking {} {} {} with desired precision"
                               "{}",
                                xc, yc, zc, xl, yl, zl, desired_precision)
   // Helper function which computes the intersection of the image ray
   // with the ellipsoid.  All vectors are in earth-centered-fixed
   // coordinate system with origin at the center of the earth.

   const int MKTR = 10;

   double ap, bp, k;
   ap = m_majorAxis + height;
   bp = m_minorAxis + height;
   k = ap * ap / (bp * bp);

   // Solve quadratic equation for scale factor
   // applied to image ray to compute ground point

   double at, bt, ct, quadTerm;
   at = xl * xl + yl * yl + k * zl * zl;
   bt = 2.0 * (xl * xc + yl * yc + k * zl * zc);
   ct = xc * xc + yc * yc + k * zc * zc - ap * ap;
   quadTerm = bt * bt - 4.0 * at * ct;

   // If quadTerm is negative, the image ray does not
   // intersect the ellipsoid. Setting the quadTerm to
   // zero means solving for a point on the ray nearest
   // the surface of the ellisoid.

   if (0.0 > quadTerm)
   {
      quadTerm = 0.0;
   }
   double scale, scale1, h, slope;
   double sprev, hprev;
   double sTerm;
   int ktr = 0;

   // Compute ground point vector

   sTerm = sqrt(quadTerm);
   scale = (-bt - sTerm);
   scale1 = (-bt + sTerm);
   if (fabs(scale1) < fabs(scale))
      scale = scale1;
   scale /= (2.0 * at);
   x = xc + scale * xl;
   y = yc + scale * yl;
   z = zc + scale * zl;
   h = computeEllipsoidElevation(x, y, z, m_majorAxis, m_minorAxis, desired_precision);
   slope = -1;

   achieved_precision = fabs(height - h);
   MESSAGE_LOG("losEllipsoidIntersect: found intersect at {} {} {}"
                                "with achieved precision of {}",
                                x, y, z, achieved_precision)
}

//***************************************************************************
// UsgsAstroLsSensorModel::losPlaneIntersect
//**************************************************************************
void UsgsAstroLsSensorModel::losPlaneIntersect(
   const double& xc,          // input: camera x coordinate
   const double& yc,          // input: camera y coordinate
   const double& zc,          // input: camera z coordinate
   const double& xl,          // input: component x image ray
   const double& yl,          // input: component y image ray
   const double& zl,          // input: component z image ray
   double&       x,           // input/output: ground x coordinate
   double&       y,           // input/output: ground y coordinate
   double&       z,           // input/output: ground z coordinate
   int&          mode) const // input: -1 fixed component to be computed
                          //         0(X), 1(Y), or 2(Z) fixed
                          // output: 0(X), 1(Y), or 2(Z) fixed
{
  MESSAGE_LOG("Calculating losPlaneIntersect for camera position"
                              "{} {} {} and image ray {} {} {}",
                              xc, yc, zc, xl, yl, zl)
   //# func_description
   //  Computes 2 of the 3 coordinates of a ground point given the 3rd
   //  coordinate.  The 3rd coordinate that is held fixed corresponds
   //  to the largest absolute component of the image ray.

   // Define fixed or largest component

   if (-1 == mode)
   {
      if (fabs(xl) > fabs(yl) && fabs(xl) > fabs(zl))
      {
         mode = 0;
      }
      else if (fabs(yl) > fabs(xl) && fabs(yl) > fabs(zl))
      {
         mode = 1;
      }
      else
      {
         mode = 2;
      }
   }
   MESSAGE_LOG("losPlaneIntersect: largest/fixed image ray component"
                                "{} (1-x, 2-y, 3-z)", mode)
   // X is the fixed or largest component

   if (0 == mode)
   {
      y = yc + (x - xc) * yl / xl;
      z = zc + (x - xc) * zl / xl;
   }

   // Y is the fixed or largest component

   else if (1 == mode)
   {
      x = xc + (y - yc) * xl / yl;
      z = zc + (y - yc) * zl / yl;
   }

   // Z is the fixed or largest component

   else
   {
      x = xc + (z - zc) * xl / zl;
      y = yc + (z - zc) * yl / zl;
   }
   MESSAGE_LOG("ground coordinate {} {} {}", x, y, z)
}

//***************************************************************************
// UsgsAstroLsSensorModel::imageToPlane
//***************************************************************************
void UsgsAstroLsSensorModel::imageToPlane(
   const double& line,      // CSM Origin UL corner of UL pixel
   const double& sample,    // CSM Origin UL corner of UL pixel
   const double& height,
   const std::vector<double> &adj,
   double&       x,
   double&       y,
   double&       z,
   int&          mode) const
{
  MESSAGE_LOG("Computing imageToPlane")
   //# func_description
   //  Computes ground coordinates by intersecting image ray with
   //  a plane perpendicular to the coordinate axis with the largest
   //  image ray component.  This routine is primarily called by
   //  groundToImage().

   // *** Computes camera position and image ray in ecf cs.

   double xc, yc, zc;
   double vx, vy, vz;
   double xl, yl, zl;
   double dxl, dyl, dzl;

   losToEcf(line, sample, adj, xc, yc, zc, vx, vy, vz, xl, yl, zl);

   losPlaneIntersect(xc, yc, zc, xl, yl, zl, x, y, z, mode);
}

//***************************************************************************
// UsgsAstroLineScannerSensorModel::getAdjSensorPosVel
//***************************************************************************
void UsgsAstroLsSensorModel::getAdjSensorPosVel(
   const double& time,
   const std::vector<double> &adj,
   double&       xc,
   double&       yc,
   double&       zc,
   double&       vx,
   double&       vy,
   double&       vz) const
{
  MESSAGE_LOG("Calculating getAdjSensorPosVel at time {}",
                              time)

   // Sensor position and velocity (4th or 8th order Lagrange).
   int nOrder = 8;
   if (m_platformFlag == 0)
      nOrder = 4;
   double sensPosNom[3];
   lagrangeInterp(m_numPositions/3, &m_positions[0], m_t0Ephem, m_dtEphem,
      time, 3, nOrder, sensPosNom);
   double sensVelNom[3];
   lagrangeInterp(m_numPositions/3, &m_velocities[0], m_t0Ephem, m_dtEphem,
      time, 3, nOrder, sensVelNom);

   MESSAGE_LOG("getAdjSensorPosVel: using {} order Lagrange",
                                nOrder)

   // Compute rotation matrix from ICR to ECF
   double radialUnitVec[3];
   double radMag = sqrt(sensPosNom[0] * sensPosNom[0] +
      sensPosNom[1] * sensPosNom[1] +
      sensPosNom[2] * sensPosNom[2]);
   for (int i = 0; i < 3; i++)
      radialUnitVec[i] = sensPosNom[i] / radMag;
   double crossTrackUnitVec[3];
   crossTrackUnitVec[0] = sensPosNom[1] * sensVelNom[2]
      - sensPosNom[2] * sensVelNom[1];
   crossTrackUnitVec[1] = sensPosNom[2] * sensVelNom[0]
      - sensPosNom[0] * sensVelNom[2];
   crossTrackUnitVec[2] = sensPosNom[0] * sensVelNom[1]
      - sensPosNom[1] * sensVelNom[0];
   double crossMag = sqrt(crossTrackUnitVec[0] * crossTrackUnitVec[0] +
      crossTrackUnitVec[1] * crossTrackUnitVec[1] +
      crossTrackUnitVec[2] * crossTrackUnitVec[2]);
   for (int i = 0; i < 3; i++)
      crossTrackUnitVec[i] /= crossMag;
   double inTrackUnitVec[3];
   inTrackUnitVec[0] = crossTrackUnitVec[1] * radialUnitVec[2]
      - crossTrackUnitVec[2] * radialUnitVec[1];
   inTrackUnitVec[1] = crossTrackUnitVec[2] * radialUnitVec[0]
      - crossTrackUnitVec[0] * radialUnitVec[2];
   inTrackUnitVec[2] = crossTrackUnitVec[0] * radialUnitVec[1]
      - crossTrackUnitVec[1] * radialUnitVec[0];
   double ecfFromIcr[9];
   ecfFromIcr[0] = inTrackUnitVec[0];
   ecfFromIcr[1] = crossTrackUnitVec[0];
   ecfFromIcr[2] = radialUnitVec[0];
   ecfFromIcr[3] = inTrackUnitVec[1];
   ecfFromIcr[4] = crossTrackUnitVec[1];
   ecfFromIcr[5] = radialUnitVec[1];
   ecfFromIcr[6] = inTrackUnitVec[2];
   ecfFromIcr[7] = crossTrackUnitVec[2];
   ecfFromIcr[8] = radialUnitVec[2];

   // Apply position and velocity corrections
   double aTime = time - m_t0Ephem;
   double dvi = getValue(3, adj) / m_halfTime;
   double dvc = getValue(4, adj) / m_halfTime;
   double dvr = getValue(5, adj) / m_halfTime;
   vx = sensVelNom[0]
      + ecfFromIcr[0] * dvi + ecfFromIcr[1] * dvc + ecfFromIcr[2] * dvr;
   vy = sensVelNom[1]
      + ecfFromIcr[3] * dvi + ecfFromIcr[4] * dvc + ecfFromIcr[5] * dvr;
   vz = sensVelNom[2]
      + ecfFromIcr[6] * dvi + ecfFromIcr[7] * dvc + ecfFromIcr[8] * dvr;
   double di = getValue(0, adj) + dvi * aTime;
   double dc = getValue(1, adj) + dvc * aTime;
   double dr = getValue(2, adj) + dvr * aTime;
   xc = sensPosNom[0]
      + ecfFromIcr[0] * di + ecfFromIcr[1] * dc + ecfFromIcr[2] * dr;
   yc = sensPosNom[1]
      + ecfFromIcr[3] * di + ecfFromIcr[4] * dc + ecfFromIcr[5] * dr;
   zc = sensPosNom[2]
      + ecfFromIcr[6] * di + ecfFromIcr[7] * dc + ecfFromIcr[8] * dr;

   MESSAGE_LOG("getAdjSensorPosVel: postition {} {} {}"
                                "and velocity {} {} {}",
                              xc, yc, zc, vx, vy, vz)
}


//***************************************************************************
// UsgsAstroLineScannerSensorModel::computeDetectorView
//***************************************************************************
std::vector<double> UsgsAstroLsSensorModel::computeDetectorView(
   const double& time,
   const csm::EcefCoord& groundPoint,
   const std::vector<double>& adj) const
{
  MESSAGE_LOG("Computing computeDetectorView (with adjusments)"
                              "for ground point {} {} {} at time {} ",
                              groundPoint.x, groundPoint.y, groundPoint.z, time)


  // Helper function to compute the CCD pixel that views a ground point based
  // on the exterior orientation at a given time.

   // Get the exterior orientation
   double xc, yc, zc, vx, vy, vz;
   getAdjSensorPosVel(time, adj, xc, yc, zc, vx, vy, vz);

   // Compute the look vector
   double bodyLookX = groundPoint.x - xc;
   double bodyLookY = groundPoint.y - yc;
   double bodyLookZ = groundPoint.z - zc;
   MESSAGE_LOG("computeDetectorView: look vector {} {} {}",
                                bodyLookX, bodyLookY, bodyLookZ)

   // Rotate the look vector into the camera reference frame
   double quaternions[4];
   getQuaternions(time, quaternions);
   double bodyToCamera[9];
   calculateRotationMatrixFromQuaternions(quaternions, bodyToCamera);

   // Apply transpose of matrix to rotate body->camera
   double cameraLookX = bodyToCamera[0] * bodyLookX
                      + bodyToCamera[3] * bodyLookY
                      + bodyToCamera[6] * bodyLookZ;
   double cameraLookY = bodyToCamera[1] * bodyLookX
                      + bodyToCamera[4] * bodyLookY
                      + bodyToCamera[7] * bodyLookZ;
   double cameraLookZ = bodyToCamera[2] * bodyLookX
                      + bodyToCamera[5] * bodyLookY
                      + bodyToCamera[8] * bodyLookZ;
   MESSAGE_LOG("computeDetectorView: look vector (camrea ref frame)"
                               "{} {} {}",
                                cameraLookX, cameraLookY, cameraLookZ)

   // Invert the attitude correction
   double attCorr[9];
   calculateAttitudeCorrection(time, adj, attCorr);

   // Apply transpose of matrix to invert the attidue correction
   double adjustedLookX = attCorr[0] * cameraLookX
                        + attCorr[3] * cameraLookY
                        + attCorr[6] * cameraLookZ;
   double adjustedLookY = attCorr[1] * cameraLookX
                        + attCorr[4] * cameraLookY
                        + attCorr[7] * cameraLookZ;
   double adjustedLookZ = attCorr[2] * cameraLookX
                        + attCorr[5] * cameraLookY
                        + attCorr[8] * cameraLookZ;
   MESSAGE_LOG("computeDetectorView: adjusted look vector"
                               "{} {} {}",
                                adjustedLookX, adjustedLookY, adjustedLookZ)

   // Convert to focal plane coordinate
   double lookScale = (m_focalLength  + getValue(15, adj)) / adjustedLookZ;
   double focalX = adjustedLookX * lookScale;
   double focalY = adjustedLookY * lookScale;

   MESSAGE_LOG("computeDetectorView: focal plane coordinates"
                         "x:{} y:{} scale:{}",
                         focalX, focalY, lookScale)

   return std::vector<double> {focalX, focalY};
}


//***************************************************************************
// UsgsAstroLineScannerSensorModel::computeLinearApproximation
//***************************************************************************
void UsgsAstroLsSensorModel::computeLinearApproximation(
   const csm::EcefCoord &gp,
   csm::ImageCoord      &ip) const
{
   if (_linear)
   {
      ip.line = _u0 + _du_dx * gp.x + _du_dy * gp.y + _du_dz * gp.z;
      ip.samp = _v0 + _dv_dx * gp.x + _dv_dy * gp.y + _dv_dz * gp.z;

      // Since this is valid only over image,
      // don't let result go beyond the image border.
      double numRows = m_nLines;
      double numCols = m_nSamples;
      if (ip.line < 0.0)     ip.line = 0.0;
      if (ip.line > numRows) ip.line = numRows;

      if (ip.samp < 0.0)     ip.samp = 0.0;
      if (ip.samp > numCols) ip.samp = numCols;
      MESSAGE_LOG("Computing computeLinearApproximation"
                                  "with linear approximation")
   }
   else
   {
      ip.line = m_nLines / 2.0;
      ip.samp = m_nSamples / 2.0;
      MESSAGE_LOG("Computing computeLinearApproximation"
                                  "nonlinear approx line/2 and sample/2")
   }
}


//***************************************************************************
// UsgsAstroLineScannerSensorModel::setLinearApproximation
//***************************************************************************
void UsgsAstroLsSensorModel::setLinearApproximation()
{
  MESSAGE_LOG("Calculating setLinearApproximation")
  double u_factors[4] = { 0.0, 0.0, 1.0, 1.0 };
  double v_factors[4] = { 0.0, 1.0, 0.0, 1.0 };

  csm::EcefCoord refPt = getReferencePoint();

  double desired_precision = 0.01;
  double height = computeEllipsoidElevation(
        refPt.x, refPt.y, refPt.z,
        m_majorAxis, m_minorAxis, desired_precision);
  if (std::isnan(height))
  {
    MESSAGE_LOG("setLinearApproximation: computeElevation of"
                                "reference point {} {} {} with desired precision"
                                "{} returned nan height; nonlinear",
                                refPt.x, refPt.y, refPt.z, desired_precision)
    _linear = false;
    return;
  }
  MESSAGE_LOG("setLinearApproximation: computeElevation of"
                              "reference point {} {} {} with desired precision"
                              "{} returned {} height",
                              refPt.x, refPt.y, refPt.z, desired_precision, height)

  double numRows = m_nLines;
  double numCols = m_nSamples;

  csm::ImageCoord imagePt;
  csm::EcefCoord  gp[8];

  int i;
  for (i = 0; i < 4; i++)
  {
    imagePt.line = u_factors[i] * numRows;
    imagePt.samp = v_factors[i] * numCols;
    gp[i] = imageToGround(imagePt, height);
  }

  double delz = 100.0;
  height += delz;
  for (i = 0; i < 4; i++)
  {
    imagePt.line = u_factors[i] * numRows;
    imagePt.samp = v_factors[i] * numCols;
    gp[i + 4] = imageToGround(imagePt, height);
  }

  csm::EcefCoord d_du;
  d_du.x = (
    (gp[2].x + gp[3].x + gp[6].x + gp[7].x) -
    (gp[0].x + gp[1].x + gp[4].x + gp[5].x)) / numRows / 4.0;
  d_du.y = (
    (gp[2].y + gp[3].y + gp[6].y + gp[7].y) -
    (gp[0].y + gp[1].y + gp[4].y + gp[5].y)) / numRows / 4.0;
  d_du.z = (
    (gp[2].z + gp[3].z + gp[6].z + gp[7].z) -
    (gp[0].z + gp[1].z + gp[4].z + gp[5].z)) / numRows / 4.0;

  csm::EcefCoord d_dv;
  d_dv.x = (
    (gp[1].x + gp[3].x + gp[5].x + gp[7].x) -
    (gp[0].x + gp[2].x + gp[4].x + gp[6].x)) / numCols / 4.0;
  d_dv.y = (
    (gp[1].y + gp[3].y + gp[5].y + gp[7].y) -
    (gp[0].y + gp[2].y + gp[4].y + gp[6].y)) / numCols / 4.0;
  d_dv.z = (
    (gp[1].z + gp[3].z + gp[5].z + gp[7].z) -
    (gp[0].z + gp[2].z + gp[4].z + gp[6].z)) / numCols / 4.0;

  double mat3x3[9];

  mat3x3[0] = d_du.x;
  mat3x3[1] = d_dv.x;
  mat3x3[2] = 1.0;
  mat3x3[3] = d_du.y;
  mat3x3[4] = d_dv.y;
  mat3x3[5] = 1.0;
  mat3x3[6] = d_du.z;
  mat3x3[7] = d_dv.z;
  mat3x3[8] = 1.0;

  double denom = determinant3x3(mat3x3);

  if (fabs(denom) < 1.0e-8) // can not get derivatives this way
  {
    MESSAGE_LOG("setLinearApproximation: determinant3x3 of"
                                "matrix of partials is {}; nonlinear",
                                denom)
    _linear = false;
    return;
  }

  mat3x3[0] = 1.0;
  mat3x3[3] = 0.0;
  mat3x3[6] = 0.0;
  _du_dx = determinant3x3(mat3x3) / denom;

  mat3x3[0] = 0.0;
  mat3x3[3] = 1.0;
  mat3x3[6] = 0.0;
  _du_dy = determinant3x3(mat3x3) / denom;

  mat3x3[0] = 0.0;
  mat3x3[3] = 0.0;
  mat3x3[6] = 1.0;
  _du_dz = determinant3x3(mat3x3) / denom;

  mat3x3[0] = d_du.x;
  mat3x3[3] = d_du.y;
  mat3x3[6] = d_du.z;

  mat3x3[1] = 1.0;
  mat3x3[4] = 0.0;
  mat3x3[7] = 0.0;
  _dv_dx = determinant3x3(mat3x3) / denom;

  mat3x3[1] = 0.0;
  mat3x3[4] = 1.0;
  mat3x3[7] = 0.0;
  _dv_dy = determinant3x3(mat3x3) / denom;

  mat3x3[1] = 0.0;
  mat3x3[4] = 0.0;
  mat3x3[7] = 1.0;
  _dv_dz = determinant3x3(mat3x3) / denom;

  _u0 = -gp[0].x * _du_dx - gp[0].y * _du_dy - gp[0].z * _du_dz;
  _v0 = -gp[0].x * _dv_dx - gp[0].y * _dv_dy - gp[0].z * _dv_dz;

  _linear = true;
  MESSAGE_LOG("Completed setLinearApproximation")
}

//***************************************************************************
// UsgsAstroLineScannerSensorModel::determinant3x3
//***************************************************************************
double UsgsAstroLsSensorModel::determinant3x3(double mat[9]) const
{
  return
    mat[0] * (mat[4] * mat[8] - mat[7] * mat[5]) -
    mat[1] * (mat[3] * mat[8] - mat[6] * mat[5]) +
    mat[2] * (mat[3] * mat[7] - mat[6] * mat[4]);
}


//***************************************************************************
// UsgsAstroLineScannerSensorModel::constructStateFromIsd
//***************************************************************************
std::string UsgsAstroLsSensorModel::constructStateFromIsd(const std::string imageSupportData, csm::WarningList *warnings)
{
  json state = {};
  MESSAGE_LOG("Constructing state from Isd")
  // Instantiate UsgsAstroLineScanner sensor model
  json isd = json::parse(imageSupportData);

  csm::WarningList* parsingWarnings = new csm::WarningList;

  int num_params = NUM_PARAMETERS;

  state["m_modelName"] = getSensorModelName(isd, parsingWarnings);
  state["m_imageIdentifier"] = getImageId(isd, parsingWarnings);
  state["m_sensorName"] = getSensorName(isd, parsingWarnings);
  state["m_platformName"] = getPlatformName(isd, parsingWarnings);
  MESSAGE_LOG("m_modelName: {} "
              "m_imageIdentifier: {} "
              "m_sensorName: {} "
              "m_platformName: {} ",
              state["m_modelName"].dump(),
              state["m_imageIdentifier"].dump(),
              state["m_sensorName"].dump(),
              state["m_platformName"].dump())

  state["m_focalLength"] = getFocalLength(isd, parsingWarnings);
  MESSAGE_LOG("m_focalLength: {} ", state["m_focalLength"].dump())

  state["m_nLines"] = getTotalLines(isd, parsingWarnings);
  state["m_nSamples"] = getTotalSamples(isd, parsingWarnings);
  MESSAGE_LOG("m_nLines: {} "
              "m_nSamples: {} ",
              state["m_nLines"].dump(), state["m_nSamples"].dump())

  state["m_iTransS"] = getFocal2PixelSamples(isd, parsingWarnings);
  state["m_iTransL"] = getFocal2PixelLines(isd, parsingWarnings);
  MESSAGE_LOG("m_iTransS: {} "
              "m_iTransL: {} ",
              state["m_iTransS"].dump(), state["m_iTransL"].dump())

  state["m_platformFlag"] = 1;
  state["m_ikCode"] = 0;
  state["m_zDirection"] = 1;
  MESSAGE_LOG("m_platformFlag: {} "
              "m_ikCode: {} "
              "m_zDirection: {} ",
              state["m_platformFlag"].dump(), state["m_ikCode"].dump(),
              state["m_zDirection"].dump())

  state["m_distortionType"] = getDistortionModel(isd, parsingWarnings);
  state["m_opticalDistCoeffs"] = getDistortionCoeffs(isd, parsingWarnings);
  MESSAGE_LOG("m_distortionType: {} "
              "m_opticalDistCoeffs: {} ",
              state["m_distortionType"].dump(),
              state["m_opticalDistCoeffs"].dump())

  // Zero computed state values
  state["m_referencePointXyz"] = std::vector<double>(3, 0.0);
  MESSAGE_LOG("m_referencePointXyz: {} ",
                        state["m_referencePointXyz"].dump())

  // sun_position and velocity are required for getIlluminationDirection
  state["m_sunPosition"]= getSunPositions(isd, parsingWarnings);
  state["m_sunVelocity"]= getSunVelocities(isd, parsingWarnings);

  // leave these be for now.
  state["m_gsd"] = 1.0;
  state["m_flyingHeight"] = 1000.0;
  state["m_halfSwath"] = 1000.0;
  state["m_halfTime"] = 10.0;
  MESSAGE_LOG("m_gsd: {} "
              "m_flyingHeight: {} "
              "m_halfSwath: {} "
              "m_halfTime: {} ",
              state["m_gsd"].dump(), state["m_flyingHeight"].dump(),
              state["m_halfSwath"].dump(), state["m_halfTime"].dump())

  state["m_centerEphemerisTime"] = getCenterTime(isd, parsingWarnings);
  state["m_startingEphemerisTime"] = getStartingTime(isd, parsingWarnings);
  MESSAGE_LOG("m_centerEphemerisTime: {} "
              "m_startingEphemerisTime: {} ",
              state["m_centerEphemerisTime"].dump(),
              state["m_startingEphemerisTime"].dump())

  state["m_intTimeLines"] = getIntegrationStartLines(isd, parsingWarnings);
  state["m_intTimeStartTimes"] = getIntegrationStartTimes(isd, parsingWarnings);
  state["m_intTimes"] = getIntegrationTimes(isd, parsingWarnings);
  MESSAGE_LOG("m_intTimeLines: {} "
                        "m_intTimeStartTimes: {} "
                        "m_intTimes: {} ",
                        state["m_intTimeLines"].dump(),
                        state["m_intTimeStartTimes"].dump(),
                        state["m_intTimes"].dump())

  state["m_detectorSampleSumming"] = getSampleSumming(isd, parsingWarnings);
  state["m_detectorLineSumming"] = getLineSumming(isd, parsingWarnings);
  state["m_startingDetectorSample"] = getDetectorStartingSample(isd, parsingWarnings);
  state["m_startingDetectorLine"] = getDetectorStartingLine(isd, parsingWarnings);
  state["m_detectorSampleOrigin"] = getDetectorCenterSample(isd, parsingWarnings);
  state["m_detectorLineOrigin"] = getDetectorCenterLine(isd, parsingWarnings);
  MESSAGE_LOG("m_detectorSampleSumming: {} "
              "m_detectorLineSumming: {}"
              "m_startingDetectorSample: {} "
              "m_startingDetectorLine: {} "
              "m_detectorSampleOrigin: {} "
              "m_detectorLineOrigin: {} ",
              state["m_detectorSampleSumming"].dump(),
              state["m_detectorLineSumming"].dump(),
              state["m_startingDetectorSample"].dump(),
              state["m_startingDetectorLine"].dump(),
              state["m_detectorSampleOrigin"].dump(),
              state["m_detectorLineOrigin"].dump())


  // These are exlusive to LineScanners, leave them here for now.
  try {
    state["m_dtEphem"] = isd.at("dt_ephemeris");
    MESSAGE_LOG("m_dtEphem: {} ", state["m_dtEphem"].dump())
  }
  catch(...) {
    parsingWarnings->push_back(
      csm::Warning(
        csm::Warning::DATA_NOT_AVAILABLE,
        "dt_ephemeris not in ISD",
        "UsgsAstroFrameSensorModel::constructStateFromIsd()"));
    MESSAGE_LOG("m_dtEphem not in ISD")
  }

  try {
    state["m_t0Ephem"] = isd.at("t0_ephemeris");
    MESSAGE_LOG("t0_ephemeris: {}", state["m_t0Ephem"].dump())
  }
  catch(...) {
    parsingWarnings->push_back(
      csm::Warning(
        csm::Warning::DATA_NOT_AVAILABLE,
        "t0_ephemeris not in ISD",
        "UsgsAstroFrameSensorModel::constructStateFromIsd()"));
    MESSAGE_LOG("t0_ephemeris not in ISD")
  }

  try{
    state["m_dtQuat"] = isd.at("dt_quaternion");
    MESSAGE_LOG("dt_quaternion: {}", state["m_dtQuat"].dump())
  }
  catch(...) {
    parsingWarnings->push_back(
      csm::Warning(
        csm::Warning::DATA_NOT_AVAILABLE,
        "dt_quaternion not in ISD",
        "UsgsAstroFrameSensorModel::constructStateFromIsd()"));
    MESSAGE_LOG("dt_quaternion not in ISD")
  }

  try{
    state["m_t0Quat"] =  isd.at("t0_quaternion");
    MESSAGE_LOG("m_t0Quat: {}", state["m_t0Quat"].dump())
  }
  catch(...) {
    parsingWarnings->push_back(
      csm::Warning(
        csm::Warning::DATA_NOT_AVAILABLE,
        "t0_quaternion not in ISD",
        "UsgsAstroFrameSensorModel::constructStateFromIsd()"));
    MESSAGE_LOG("t0_quaternion not in ISD")
  }

  std::vector<double> positions = getSensorPositions(isd, parsingWarnings);
  state["m_positions"] = positions;
  state["m_numPositions"] = positions.size();
  MESSAGE_LOG("m_positions: {}"
              "m_numPositions: {}",
              state["m_positions"].dump(),
              state["m_numPositions"].dump())

  state["m_velocities"] = getSensorVelocities(isd, parsingWarnings);
  MESSAGE_LOG("m_velocities: {}",
              state["m_velocities"].dump())

  std::vector<double> quaternions = getSensorOrientations(isd, parsingWarnings);
  state["m_quaternions"] = quaternions;
  state["m_numQuaternions"] = quaternions.size();
  MESSAGE_LOG("m_quaternions: {}"
              "m_numQuaternions: {}",
              state["m_quaternions"].dump(),
              state["m_numQuaternions"].dump())

  state["m_currentParameterValue"] = std::vector<double>(NUM_PARAMETERS, 0.0);
  MESSAGE_LOG("m_currentParameterValue: {}",
              state["m_currentParameterValue"].dump())

  // get radii
  state["m_minorAxis"] = getSemiMinorRadius(isd, parsingWarnings);
  state["m_majorAxis"] = getSemiMajorRadius(isd, parsingWarnings);
  MESSAGE_LOG("m_minorAxis: {}"
              "m_majorAxis: {}",
              state["m_minorAxis"].dump(), state["m_majorAxis"].dump())

  // set identifiers
  state["m_platformIdentifier"] = getPlatformName(isd, parsingWarnings);
  state["m_sensorIdentifier"] = getSensorName(isd, parsingWarnings);
  MESSAGE_LOG("m_platformIdentifier: {}"
              "m_sensorIdentifier: {}",
              state["m_platformIdentifier"].dump(),
              state["m_sensorIdentifier"].dump())

  // get reference_height
  state["m_minElevation"] = getMinHeight(isd, parsingWarnings);
  state["m_maxElevation"] = getMaxHeight(isd, parsingWarnings);
  MESSAGE_LOG("m_minElevation: {}"
              "m_maxElevation: {}",
              state["m_minElevation"].dump(),
              state["m_maxElevation"].dump())

  // Default to identity covariance
  state["m_covariance"] =
       std::vector<double>(NUM_PARAMETERS * NUM_PARAMETERS, 0.0);
  for (int i = 0; i < NUM_PARAMETERS; i++) {
   state["m_covariance"][i * NUM_PARAMETERS + i] = 1.0;
  }

  if (!parsingWarnings->empty()) {
    if (warnings) {
      warnings->insert(warnings->end(), parsingWarnings->begin(), parsingWarnings->end());
    }
    delete parsingWarnings;
    parsingWarnings = nullptr;
    throw csm::Error(csm::Error::SENSOR_MODEL_NOT_CONSTRUCTIBLE,
                     "ISD is invalid for creating the sensor model.",
                     "UsgsAstroFrameSensorModel::constructStateFromIsd");
  }

  delete parsingWarnings;
  parsingWarnings = nullptr;

  // The state data will still be updated when a sensor model is created since
  // some state data is not in the ISD and requires a SM to compute them.
  return state.dump();
}


//***************************************************************************
// UsgsAstroLineScannerSensorModel::getLogger
//***************************************************************************
std::shared_ptr<spdlog::logger> UsgsAstroLsSensorModel::getLogger() {
  // MESSAGE_LOG("Getting log pointer, logger is {}",
  //                             m_logger)
  return m_logger;
}

void UsgsAstroLsSensorModel::setLogger(std::string logName) {
  m_logger = spdlog::get(logName);
}


csm::EcefVector UsgsAstroLsSensorModel::getSunPosition(
  const double imageTime) const
{

  int numSunPositions = m_sunPosition.size();
  int numSunVelocities = m_sunVelocity.size();
  csm::EcefVector sunPosition = csm::EcefVector();

  // If there are multiple positions, use Lagrange interpolation
  if ((numSunPositions/3) > 1) {
    double sunPos[3];
    double endTime = m_t0Ephem + (m_dtEphem * ((m_numPositions/3)));
    double sun_dtEphem = (endTime - m_t0Ephem) / (numSunPositions/3);
    lagrangeInterp(numSunPositions/3, &m_sunPosition[0], m_t0Ephem, sun_dtEphem,
                   imageTime, 3, 8, sunPos);
    sunPosition.x = sunPos[0];
    sunPosition.y = sunPos[1];
    sunPosition.z = sunPos[2];
  }
  else if ((numSunVelocities/3) >= 1){
    // If there is one position triple with at least one velocity triple
    //  then the illumination direction is calculated via linear extrapolation.
      sunPosition.x = (imageTime * m_sunVelocity[0] + m_sunPosition[0]);
      sunPosition.y = (imageTime * m_sunVelocity[1] + m_sunPosition[1]);
      sunPosition.z = (imageTime * m_sunVelocity[2] + m_sunPosition[2]);
  }
  else {
    // If there is one position triple with no velocity triple, then the
    //  illumination direction is the difference of the original vectors.
      sunPosition.x = m_sunPosition[0];
      sunPosition.y = m_sunPosition[1];
      sunPosition.z = m_sunPosition[2];
  }
  return sunPosition;
}