[GRASS-user] shaded relief maps & custom color DEM

[Patton, Eric]

Mark,

The grass commands you are looking for are r.his and r.composite. 

r.his uses a coloured DEM as the hue component, and the shaded-relief map as the intensity component. The saturation component can be left blank in this case. r.his will output 3 maps, one each for red, blue and green color components, which you can then combine together in one map with r.composite.

You may be interested in trying out a script I wrote called r.csr that integrates all these steps in the Grass Add-ons:

http://grass.gdf-hannover.de/wiki/GRASS_AddOns#Raster_add-ons

r.csr allows you to input one or more rasters using a wildcard search pattern, and can apply color rules, shading parameters, and the r.his and r.composite steps described above all in one go.

Hope this helps,

~ Eric.


-----Original Message-----
From: grassuser-bounces at grass.itc.it on behalf of M S
Sent: Thu 5/24/2007 11:29 AM
To: grass user
Subject: [GRASS-user] shaded relief maps & custom color DEM
 
Hello all!

I have been exploring the best way to make a shaded relief map with color
gradient.  Although I have been using GIS for many years, this is a new
topic for me.  (New is always fun, especially with GRASS!)

I have several questions relating to this topic.

1)  I have used r.color to change the color gradient for the DEM I am
using.  There are a lot of nice palettes to use!  One that I am looking for
is a tan to green gradient (tan=high elev, green=low).  There are some nice
ones that are close, but is there a way to create a new color map going from
color #1 to color #2?  In the mean time, the red to yellow to blue is
working well.

2)  r.shaded.relief creates some nice outputs!  very cool. I have a ryb
color map for the DEM, and have created a shaded relief map that is
grayscale.  Is there a way to make a color shaded relief map?  I have been
looking for examples illustrating the tools to use in GRASS that will do
this.  I found r.blend, and it seems to produce something very close, if not
exactly what I am looking for with more tuning of parameters.  Is this the
best combination of tools to use? --> r.color on DEM + r.shaded.relief +
r.blend = color ramped shaded relief map?

3)  I have done a fair amount of researching the web for color shaded relief
maps, but was unable to find techniques relating to GRASS production of
these datasets, or a gallery of shaded relief maps produced by GRASS.  Does
anyone know of such a link?

Thanks
Mark