> Hamish wrote: > > I am working with MODIS Aqua imagery in HDF4 format. (level 3) ... > > I added a mini-tutorial here: > > http://grass.gdf-hannover.de/wiki/MODIS ... > > The Chlorophyll-a concentration data comes in log form, 0-65535. ... > > The metadata (available through gdalinfo) gives the formula and test > > points to convert to mg/m^3: > > r.mapcalc "${map}.chlor_a = 10^(($Slope * $map) + $Intercept)" > > > ie a histogram of that starts high and exponentially drops to 0. By > > 2.0 there are few data cells left, but real data continues up to the > > max in areas having plankton blooms. ... > > So how to make nice color rules for that? 'r.colors -g' does the > > opposite of what I want,
Glynn. > Odd. Theoretically, it should do exactly what you want. You are right, -g is the right thing to use, it's just that the data is /so/ logarithmic that it only brings out a little more detail and it appears like nothing happened. (it became clear after displaying a legend, changing the color rules, then redrawing) Hamish ____________________________________________________________________________________ You rock. That's why Blockbuster's offering you one month of Blockbuster Total Access, No Cost. http://tc.deals.yahoo.com/tc/blockbuster/text5.com ____________________________________________________________________________________ You rock. That's why Blockbuster's offering you one month of Blockbuster Total Access, No Cost. http://tc.deals.yahoo.com/tc/blockbuster/text5.com _______________________________________________ grass-dev mailing list grass-dev@lists.osgeo.org http://lists.osgeo.org/mailman/listinfo/grass-dev