info@maxar.com maxar.com
Maxar utilizes the Committee on Earth Observation Satellites (CEOS) RadCalNet
sites for validation of our on-orbit absolute radiometric calibration efforts. Maxar
compares to RadCalNet Railroad Valley, Nevada (RVUS) site within +/- 5%. This
includes the WorldView-3 SWIR instrument. RadCalNet data are given at Nadr.
Maxar sensors will typically have an off-nadir angle of 5-30 degrees. Variation in
off-nadir angle will increase the variability in Maxar data due to surface BRDF and
longer atmospheric path. <10% is considered a good comparison.
Validation via CEOS RadCalNet sites
Maxar sensors compare to
RadCalNet at about ±5%.
The aim of absolute radiometric calibration is to assign absolute scientific SI
units to pixels based on radiometric parameters such as scan direction, scan rate,
TDI level, and DN value. For WorldView-class sensors, the absolute radiometric
calibration product specification for ninety-five percent of products is:
Maxar is well within the specifications
■
"L" is at-sensor radiance found independently for each band and pixel
■
<10% of dynamic range there shall be no specification
■
Between 10% and 85% of the dynamic range the absolute radiometric response
specifications shall not exceed +/- 10% uncertainty for VNIR sensors and +/- 15%
for SWIR sensors
■
>85% of dynamic range there shall be no specification
ABSOLUTE RADIOMETRIC CALIBRATION
