i.topo.corr: handle integer input for correction

[sbl]

i.topo.corr currently seems to only correct input maps of type DCELL or FCELL.

It would be great if it could handle also integer maps as input. Maybe a quantization option, like in i.atcor would be a possibility to scale input from 1 - 10000 to 0.0 - 1.0 by applying the quantization factor (default to 1)?

I am thinking of e.g. linked (r.external) Sentinel-2 data here, which comes with integer values...

Ideally, also output should be saved as integer if input is integer, reapplying the quantization.

That could save a processing step and would possibly allow to save some storage space.

[sbl]

Little correction, FCELL input is not allowed either, though i.atcorr outputs FCELL.

So, an additional step with r.mapcalc is required to change i.atcorr output to DCELL (without gain in precision)...