Uttam Kumar said: > Hi GRASS users, > How can I compute Vegetation Indices (like Ratio, > NDVI, RVI, TVI, CTVI, TTVI etc.) in GRASS as we can do it in IDRISI. > Thanks > in advance. > Try r.mapcalc. Also see the tutorial, section "Analyzing images" (http://www.geog.uni-hannover.de/grass/gdp/grass5tutor/HTML_en/c1610.html) Moritz