[GRASS-user] check pixel by pixel

[Michael Barton]

On 10/2/07 4:41 AM, "benjamin.ducke at ufg.uni-kiel.de"
<benjamin.ducke at ufg.uni-kiel.de> wrote:

> The GIS raster data model states that each cell contains
> one and exactly one value.
> That's why raster maps are also called "fields" in spatial
> statistics. And it is why raster operations are so simple
> and efficient.
> 
> ESRI ArcGIS 9.2 (not GRASS) has raster maps with multiple
> attribute values attached to each cell -- but that's a
> perversion of the entire concept in my opinion.
> 
> I am sure there must be a way of dividing your problem into smaller
> steps such that you will be able to solve it with the standard
> raster model.
> 
>> Hi,
>> I have several raster maps (aspect, slope, tand_curv etc.). I would like
>> to combine these raster maps to one raster but without losing any
>> information. As a result i would like to have one raster map with several
>> attributes (aspect, slope, tang_curv etc.). And then I would like to check
>> Pixel by Pixel
>> 
>> if slope = steep and aspect = North etc.
>> then
>> "Value of the checked pixel" + 10
>> 
>> else

I agree with Benjamin.

This is what the map calculator is used for.

r.mapcalc 'newmap = if(slope="steep" && aspect="north",10,[do something
else])'

You can also create very complex statements using eval.

Michael


>> 
>> ....
>> 
>> Has anybody done this before? Is it possible to combine several raster
>> maps without losing any information?
>> 
>> Greets
>> 
>> Andreas
>> --
>> Ist Ihr Browser Vista-kompatibel? Jetzt die neuesten
>> Browser-Versionen downloaden: http://www.gmx.net/de/go/browser
>> 
>> _______________________________________________
>> grassuser mailing list
>> grassuser at grass.itc.it
>> http://grass.itc.it/mailman/listinfo/grassuser
>> 
>> 
> 
> 
> 

__________________________________________
Michael Barton, Professor of Anthropology
Director of Graduate Studies
School of Human Evolution & Social Change
Center for Social Dynamics & Complexity
Arizona State University

phone: 480-965-6213
fax: 480-965-7671
www: http://www.public.asu.edu/~cmbarton