[GRASSLIST:6971] Re: PS.MAP command -->overlay raster

Maciek Sieczka werchowyna at epf.pl
Wed Jun 1 13:25:42 EDT 2005


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


----- Original Message ----- 
From: "Luca Penasa" <luca.penasa at email.it>
Cc: <GRASSLIST at baylor.edu>
Sent: Wednesday, June 01, 2005 7:33 PM
Subject: [GRASSLIST:6968] PS.MAP command -->overlay raster

> Im going to export some maps with the command ps.map. I need to overlay 
> two different raster, but the command cant do it. The first one is the DTM 
> (painted with its colors), the second one is a binary raster (that contain 
> two value: null() & 1). I need a command to overlay this two raster... i 
> can use r.mapcalc, but if i use it i'll have to redefinite the color 
> table.... is there a specific command to do what i said?
> Thanks....
> Luca p
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