Planet undertake the following calibrations on our Dove satellites:

• Darkfield/Offset Correction: Corrects for sensor bias and dark noise. Master offset tables are created by averaging on-orbit darkfield collects across 5-10 degree temperature bins and applied to scenes during processing based on the CCD temperature at acquisition time.

• Flat Field Correction: Flat fields are collected for each optical instrument prior to launch. These fields are used to correct image lighting and CCD element effects to match the optimal response area of the sensor. Flat fields are routinely updated on-orbit during the satellite lifetime.

• Camera Acquisition Parameter Correction: Determines a common radiometric response for each image (regardless of exposure time, number of TDI stages, gain, camera temperature and other camera parameters).

• Absolute Calibration: As a last step, the spatially and temporally adjusted datasets are transformed from digital number values into physical based radiance values (scaled to W/(m²strμm)*100).

For SkySat the following applies:

• Darkfield/Offset Correction: Corrects for sensor bias and dark noise. Master offset tables are created by averaging on-orbit darkfield collects across 5-10 degree temperature bins and applied to scenes during processing based on the CCD temperature at acquisition time.
• Flat Field Correction: Flat fields are collected for each optical instrument prior to launch. These fields are used to correct image lighting and CCD element effects to match the optimal response area of the sensor. Flat fields are routinely updated on-orbit during the satellite lifetime.
• Camera Acquisition Parameter Correction: Determines a common radiometric response for each image (regardless of exposure time, number of TDI stages, gain, camera temperature and other camera parameters).
• Inter-Sensor Radiometric Response (Intra-Camera): Cross calibrates the 3 sensors in each camera to a common relative radiometric response. The offsets between each sensor is derived using on-orbit cloud flats and the overlap regions between sensors on SkySat spacecraft.
• Super Resolution (Level 1B Processing): Super resolution is the process of creating an improved resolution image by fusing information from low resolution images, with the created higher resolution image being a better description of the scene.

Our team is constantly improving the radiometric calibration process. For additional technical detail, refer to our On-Orbit Radiometric Calibration white paper.