Le 17 octobre 2017 13:38:34 GMT+02:00, Ken Mankoff <[email protected]> a écrit : >Dear GRASS List, > >I'm trying to do something in GRASS and can't figure out an efficient >way to do it. I'm guessing it is possible with 1-3 lines, but don't >know which ones. The algorithm I'm developing would be much more >complex, and I hope someone can suggest a shortcut. > >I have several satellite products of the same region each day. For >simplicity sake lets assume 3 overlapping solar zenith angle (SZA) >products, and for each of those a visual image (VIS). I'd like to have >one visual raster that, for each pixel, has the minimum SZA. > >I can get the minimum SZA for each pixel with > >r.mapcalc "SZA_min = min(SZA1,SZA2,SZA3)" > >But now I've lost the source of the minimum SZA, and I need it to link >SZA1 with VIS1. > >I could encode categories for each SZA: >r.category map=SZA1 cats=0-360 values=1 >r.category map=SZA2 cats=0-360 values=2 >r.category map=SZA3 cats=0-360 values=3 > >And then > >r.mapcalc "SZA_min_cat = min(@SZA1,@SZA2,@SZA3)" > >And then use SZA_min_cat (values: 1 to 3) as a lookup to >VIS1,VIS2,VIS3. I'm actually not clear how to do this last step, if >this is the correct approach. Do I return to r.mapcalc, or is r.univar >the right tool? > >Any help will be much appreciated.
Check r.series, notably the min_raster method. Moritz > >Thanks, > > -k. > >_______________________________________________ >grass-user mailing list >[email protected] >https://lists.osgeo.org/mailman/listinfo/grass-user _______________________________________________ grass-user mailing list [email protected] https://lists.osgeo.org/mailman/listinfo/grass-user
