This addresses #47 more explicitly and adds some tests to ensure the proper scale is used for the current set of metadata tags.

Justin McAllister · Justin McAllister · commit f34bdb468df6 · 2019-04-02T18:23:07.000-07:00
diff --git a/micasense/metadata.py b/micasense/metadata.py
@@ -146,11 +146,7 @@ def dls_pose(self):
         return yaw, pitch, roll
 
     def dls_irradiance(self):
-        if self.get_item('XMP:SpectralIrradiance') is not None:
-            irr = float(self.get_item('XMP:SpectralIrradiance'))
-        else:
-            irr = 0.0
-        return irr
+        return self.spectral_irradiance()
 
     def rig_relatives(self):
         if self.get_item('XMP:RigRelatives') is not None:
@@ -266,17 +262,32 @@ def __float_or_zero(self, str):
         else:
             return 0.0
 
+    # due to calibration differences between DLS1 and DLS2, we need to account for a scale factor
+    # change in their respective units. This scale factor is pulled from the image metadata, or, if
+    # the metadata doesn't give us the scale, we assume one based on a known combination of tags
+    def irradiance_scale_factor(self):
+        if self.get_item('XMP:IrradianceScaleToSIUnits') is not None:
+             # the metadata contains the scale
+            scale_factor = self.__float_or_zero(self.get_item('XMP:IrradianceScaleToSIUnits'))
+        elif self.get_item('XMP:HorizontalIrradiance') is not None: 
+            # DLS2 but the metadata is missing the scale, assume 0.01
+            scale_factor = 0.01
+        else:
+            # DLS1, so we use a scale of 1
+            scale_factor = 1.0
+        return scale_factor
+
     def spectral_irradiance(self):
-        return self.__float_or_zero(self.get_item('XMP:SpectralIrradiance'))
+        return self.__float_or_zero(self.get_item('XMP:SpectralIrradiance'))*self.irradiance_scale_factor()
 
     def horizontal_irradiance(self):
-        return self.__float_or_zero(self.get_item('XMP:HorizontalIrradiance'))/100.0
+        return self.__float_or_zero(self.get_item('XMP:HorizontalIrradiance'))*self.irradiance_scale_factor()
 
     def scattered_irradiance(self):
-        return self.__float_or_zero(self.get_item('XMP:ScatteredIrradiance'))
+        return self.__float_or_zero(self.get_item('XMP:ScatteredIrradiance'))*self.irradiance_scale_factor()
 
     def direct_irradiance(self):
-        return self.__float_or_zero(self.get_item('XMP:DirectIrradiance'))
+        return self.__float_or_zero(self.get_item('XMP:DirectIrradiance'))*self.irradiance_scale_factor()
 
     def solar_azimuth(self):
         return self.__float_or_zero(self.get_item('XMP:SolarAzimuth'))
diff --git a/tests/conftest.py b/tests/conftest.py
@@ -138,4 +138,8 @@ def meta_v3():
 @pytest.fixture()
 def meta_bad_exposure():
     image_path = os.path.join('data', '0001SET', '000')
-    return metadata.Metadata(os.path.join(image_path, 'IMG_0003_1.tif'))
+    return metadata.Metadata(os.path.join(image_path, 'IMG_0003_1.tif'))
+
+@pytest.fixture()
+def meta_altum_dls2(altum_flight_image_name):
+    return metadata.Metadata(altum_flight_image_name)
diff --git a/tests/test_metadata.py b/tests/test_metadata.py
@@ -125,4 +125,10 @@ def test_good_exposure_v3(meta_v3):
     assert meta_v3.exposure() == pytest.approx(0.00171)
 
 def test_bad_exposure_time(meta_bad_exposure):
-    assert meta_bad_exposure.exposure() == pytest.approx(247e-6, abs=1e-3)
+    assert meta_bad_exposure.exposure() == pytest.approx(247e-6, abs=1e-3)
+
+def test_dls1_scale_factor(meta):
+    assert meta.irradiance_scale_factor() == pytest.approx(1.0)
+
+def test_dls2_scale_factor(meta_altum_dls2):
+    assert meta_altum_dls2.irradiance_scale_factor() == pytest.approx(0.01)
