[GRASSLIST:6974] Re: PS.MAP command -->overlay raster

[Maciek Sieczka]

From: "Maciek Sieczka" <werchowyna at epf.pl>

Let me correct myself:

> Luca
>
> You could use r.patch. What is null in your overlay will be taken 
> transparent and filled with your DTM. In order for the color tables to be 
> preseved make sure that no same values are present in both your rasters - 
> i.e. if your DTM is 1-1000 then recode your overlay to start at 1001.
>
> That will make your DTM hard-overlayed. An effect of semi-transparency you 
> could achieve using r.his Your DTM should be the hue, overlay should be 
> the intensity, saturation you can omit. Use r.composite to compose the 
> output back into a color Grass layer and enjoy (slight lose of quality as 
> "only" 32768 colors is a practical

> minimum

should be a "maximum" of course, sorry

> for Grass) or use 'rgb' command directly in ps.map (for best quality).

Maciek