From cd51f0143e8f6f8062fd087e806ea2fbabfbec2b Mon Sep 17 00:00:00 2001
From: Kaitlyn Lee <kdl222@nau.edu>
Date: Thu, 25 Jul 2019 13:07:33 -0700
Subject: [PATCH] Fixed how the ephemeris start time and exposure duration are
calculated for LRO (#223)
* Fixed how the ephemeris start time and exposure duration are calculated for LRO
* Added lro tests.
---
ale/drivers/lro_drivers.py | 74 +++++++++++++++++++++++++++++++
tests/pytests/test_lro_drivers.py | 10 +++++
2 files changed, 84 insertions(+)
diff --git a/ale/drivers/lro_drivers.py b/ale/drivers/lro_drivers.py
index c49c7e7..a52eecd 100644
--- a/ale/drivers/lro_drivers.py
+++ b/ale/drivers/lro_drivers.py
@@ -137,3 +137,77 @@ class LroLrocPds3LabelNaifSpiceDriver(NaifSpice, Pds3Label, LineScanner, Driver)
for the different options available.
"""
return 'NONE'
+
+ @property
+ def ephemeris_start_time(self):
+ """
+ The starting ephemeris time for LRO is computed by taking the
+ LRO:SPACECRAFT_CLOCK_PREROLL_COUNT, as defined in the label, and
+ adding offsets that were taken from an IAK.
+ -------
+ : double
+ Starting ephemeris time of the image
+ """
+ start_time = spice.scs2e(self.spacecraft_id, self.label['LRO:SPACECRAFT_CLOCK_PREROLL_COUNT'])
+ return start_time + self.constant_time_offset + self.additional_preroll * self.exposure_duration
+
+ @property
+ def exposure_duration(self):
+ """
+ Takes the exposure_duration defined in a parent class and adds
+ offsets taken from an IAK.
+
+ Returns
+ -------
+ : float
+ Returns the exposure duration in seconds.
+ """
+ return super().exposure_duration * (1 + self.multiplicative_line_error) + self.additive_line_error
+
+ @property
+ def multiplicative_line_error(self):
+ """
+ Returns the multiplicative line error defined in an IAK.
+
+ Returns
+ -------
+ : float
+ Returns the multiplicative line error.
+ """
+ return 0.0045
+
+ @property
+ def additive_line_error(self):
+ """
+ Returns the additive line error defined in an IAK.
+
+ Returns
+ -------
+ : float
+ Returns the additive line error.
+ """
+ return 0.0
+
+ @property
+ def constant_time_offset(self):
+ """
+ Returns the constant time offset defined in an IAK.
+
+ Returns
+ -------
+ : float
+ Returns the constant time offset.
+ """
+ return 0.0
+
+ @property
+ def additional_preroll(self):
+ """
+ Returns the addition preroll defined in an IAK.
+
+ Returns
+ -------
+ : float
+ Returns the additionl preroll.
+ """
+ return 1024.0
diff --git a/tests/pytests/test_lro_drivers.py b/tests/pytests/test_lro_drivers.py
index 6ce68da..5a39108 100644
--- a/tests/pytests/test_lro_drivers.py
+++ b/tests/pytests/test_lro_drivers.py
@@ -54,3 +54,13 @@ def test_odtk(driver):
def test_usgscsm_distortion_model(driver):
distortion_model = driver.usgscsm_distortion_model
assert distortion_model['lrolrocnac']['coefficients'] == [1.0]
+
+@patch('ale.base.label_pds3.Pds3Label.instrument_host_id', 'LRO')
+@patch('ale.drivers.lro_drivers.LroLrocPds3LabelNaifSpiceDriver.exposure_duration', 1)
+def test_ephemeris_start_time(driver):
+ with patch.dict(driver.label, {'LRO:SPACECRAFT_CLOCK_PREROLL_COUNT':'1'}) as f:
+ assert driver.ephemeris_start_time == 1024.1
+
+@patch('ale.base.label_pds3.Pds3Label.exposure_duration', 1)
+def test_exposure_duration(driver):
+ assert driver.exposure_duration == 1.0045
--
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