[GRASS-user] Importing .tiff values

[Moritz Lennert]

On 10/07/08 11:05, Jana K. wrote:
> Hello, could someone help me, please? I am rather new in grass, so far 
> I've succeeded making basic operations like creating locations, mapsets, 
> importing maps, converting projections, etc. I have downloaded european 
> landuse file which is in TIFF format. Unzipping produced several files, 
> besides the .tiff, with these extensions: .tfw, .aux, .tif.xml, .prj and 
> a .xls file containing a legend. Data in the map are categorical, the 
> legend contains reference of each category to a particular r:g:b color 
> in the map. I successfully imported the map to a new location, where I 
> set projection manually using the g.setproj, using info in .prj file. I 
> displayed the map and it seemed OK. Now, HERE IS MY PROBLEM: I used 
> r.cats to find out what are the categories in the raster file resulting 
> from the .tiff import. It gave me 44 categories from 1 to 44, apparently 
> with no labels attached. I suppose the labels need to be attached 
> somehow manually, although I don't know how yet.

r.category
or
r.support


> However, the bigger 
> problem seems to be the fact that the .xls legend file contains r:g:b 
> values and I don't know how to attach them to the 44 categories to the 
> 44 r:g:b values in the .xls legend file. MY QUESTIONS: Is there a way in 
> grass to get information on which color corresponds to which category? 

r.colors with rules=

If you want to use the xls legend file, you will have to transform its 
content to a text file in r.colors format, i.e. something like this:

0  255:255:255
2  255:255:0
5  0:255:0

Depending on the way you .xls file is structured this should be a more 
or less painless export to space seperated text...


> How does r.in.ogr use the info contained in files other than .tiff, 
> .tfw, coming in the bundle, or does it use it at all?

No, AFAIK, it only uses the tiff and tfw files. I think you should be 
able to create a location with the correct projection system by using 
"Create new location by ... georeferenced file" and pointing it to the 
.prj file, but am not sure.


Moritz