Reading DLS Irradiance Metadata

When a DLS unit is connected to the camera, irradiance measurements at the time of capture are stored in the XMP section of the image metadata. This information is open and readable using standard EXIF metadata reader tools and libraries. If you would like to apply your own processing techniques, you can look at the image metadata using a library such as Exiftool. 

  • The Irradiance field is a measurement of the spectral irradiance (W/m^2/nm) in each band. This is the raw spectral irradiance sensed by the DLS for that band. With the DLS 2, this tag is legacy and the Horizontal Irradiance tag should be used. 
  • The Horizontal Irradiance tag is not impacted by IMU errors since it uses the directional light sensors for angle compensation.
  • The Irradiance Yaw, Irradiance Pitch, and Irradiance Roll fields provide the measured orientation of the DLS in degrees

Here is an example of irradiance metadata:

$ exiftool IMG_0106_2.tif
Irradiance : 0.96050399541854858
Irradiance Roll : 1.8932661497089052
Irradiance Pitch : -7.0249684496199967
Irradiance Yaw : 57.545878211823961

 The tool used in this example is ExifTool

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