[GRASS-user] Appropriate input/output range for i.atcorr WorldView2?

[Paige Byassee]

Can anyone speak to the appropriate range/datatype of WorldView2 rasters
when using the i.atcorr module?

I.atcorr requires the input raster be converted to at-sensor-radiance
first, which I have done according to DigitalGlobe documention
<https://dg-cms-uploads-production.s3.amazonaws.com/uploads/document/file/209/ABSRADCAL_FLEET_2016v0_Rel20170606.pdf>.
DG suggests all transformations be done in FLOAT32 datatype, and i.atcorr
requires a specified input/output range that is positive.

I convert from the original DN's (delivered in UINT16) to radiance
(FLOAT32), and while my radiance values are positive, the datatype range is
not. In another sense, WV2 is encoded with an 11-bit dynamic range (i.e.
2^11-bit range), but I am unsure if any of these values are right for the
module... For example, Sentinel 2 L1C are also encoded as UINT16 with 15
significant bits. However, documentation states that the correct i.atcorr
Sentinel range is 1-10000; 10000 being a specified QUANTIFICATION_VALUE by
Sentinel.

Is there a WorldView 2 equivalent to this quantification value? Is there an
alternative range specific to WV2? Might this range be affected by the
radiance conversion? Respectively, what would be the appropriate
output/rescale range?

In general- Is the i.atcorr module seeking the literal range of the image
pixel values, the range of the datatype they're in, or the range of data
the satellite can collect?
-- 
*Paige Byassee*
Appalachian State University '19
B.S., Ecology|Certificate in GIS
(704)488-0872
byasseepaige at gmail.com
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