I'm a new user and just began with GRASS, where I learned to import 30x30 resolution ASTER files and then patch them (the six I'm working with) into one map. On QGIS, it doesn't appear that there's a similar function and all six tiles are kinda staggered regarding the color alignment. THen, how do you save the patched file and change the color schemes? Lastly, how to change the lat-long to UTM? And all this, from the same GeoTIFF file?
You can change the colortable on GRASS GIS itself using r.colors. Its very easy that way. Regarding conversion from latlon to UTM. you can enable
On the Fly projection in QGIS project properties. You can find it in Options menu also. Just choose your UTM project and click
Apply. You can now see the coordinates in meters when you move mouse over the map. To patch raster from QGIS you can install grass plugins for QGIS and run r.patch from there. If you dont want colortable assigned by GRASS. Run r.colors with -r option. It will remove any existing color table as per grass manual.