Fixed how the ephemeris start time and exposure duration are calculated for LRO (#223) (cd51f014) · Commits · aflab / astrogeology / Ale

ale/drivers/lro_drivers.py

+74 −0

Original line number	Diff line number	Diff line
		@@ -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

tests/pytests/test_lro_drivers.py

+10 −0

Original line number	Diff line number	Diff line
		@@ -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