Katerina-Karolina Karapanou: > I have a Landsat TM image (2007) and I work in GRASS 7.0.0. in Windows > 7. Once again, trying to apply the module i.landsat.toar in the right > way, via GUI, I have the outcome of 7 bands under the name Btoar1, > Btoar2 etc.
> Also trying to check the results via r-info for all bands I realized > that bands have different values and also 0 values. It would be suspicious, and most likely an error, if all bands have had the _same_ values. And, zero values are also normally there. Check what the zero pixels actually are (maybe create a new raster map with r.mapcalc for all zero pixel values). Are they just a few, in- or near-water, for example? Too dark surfaces? > For example for Band1: > | Range of data: min = 39.0688188976378 max = 193 > | > | Data Description: > | generated by i.landsat.toar > | > | Comments: > | Radiance of Landsat-5 TM (method uncorrected) > | ----------------------------------------------------------------- > | Acquisition date (and time) ........... 2007-06-24 (-0.0000 h) > | Production date ....................... 2014-05-09 > | > | Earth-sun distance (d) ................ 0.0000000 > | Sun elevation (and azimuth) ........... -0.00000 (0.00000) > | Digital number (DN) range ............. 0 to 0 > | Calibration constants (Lmin to Lmax) .. +0.00000 to +0.00000 > | DN to Radiance (gain and bias) ........ -0.00000 and +0.00000 > | Mean solar irradiance (ESUN) .......... -0.000 > | Radiance to Reflectance (divide by) ... -0.00000 > | ------------------------------------------------------------------ > | > | i.landsat.toar -r input="B" output="Btoar" > metfile="C:\Users\User\Desktop\thessaloniki\2007tm\thessaloniki2007tm\LT51840322007175MOR00_M\ > > | TL.txt" sensor="tm5" method="uncorrected" percent=0.01 pixel=1000 > rayleigh=0.0 scale=1.0 The all zero values for band #1 may, inded, worth re-checking your processing. But the rest, below, looks ok to me. It's not unusual to have a few "erroneous" negative values. Check how many. I guess just a few. There are various reasons why this can happen (search in the literature). > Also for band2: min: 27.571968503937 max: 365 > band3: min: 13.4456692913386 max: 264 > band4:min: -0.633976377952756 max:221 > band5:min: 0.231771653543307 max: 30.2 > band6:min: 8.87961417322835 max: 12.3681771653543 > band7:min: -0.15 max: 16.5 > > What I can do??? Remember, these are Radianve valuse, not Reflectances. So, they seem quite normal. Maybe you can set the begative pixels to zero. This will not harm, I think, your processing chain. Nikos _______________________________________________ grass-user mailing list [email protected] http://lists.osgeo.org/mailman/listinfo/grass-user
