[GRASS-user] Re: New modules in svn add-on: r.area and r.convergence

[Marcello Gorini]

Jarek Jasiewicz wrote:
> 
> Hi
> 
> I added new two modules to svn add-on.
> 
> r.area
> 
> Simple module available in almost every raster processing GIS 
> application. Calculates area size of clumped areas and ascribe these 
> values to these areas. Also allow remove small areas with size lower 
> than treshold. All that functionality can be attempted with  few 
> existing grass commands (r.to.vect, v.db.addcolumn, v.to.db v.to.rast, 
> r.mapcalc sequentially) but I spend less time programing this module 
> than performing this set of operation (on rather huge map with over 
> 100000 cluped areas)
> 
> r.convergence
> 
> specializing module reworked from SAGA. Calculate convergnece index for 
> given area based on DEM. Good wor detecting geomorphological lineaments. 
> It use different method for slope-aspect calculation than SAGA (but the 
> same as in GRASS r.slope.aspect), also can work in lat-long projections.
> 
> As always any comments, tests, suggestions and critics are welcome
> 
> Jarek
> _______________________________________________
> grass-user mailing list
> grass-user at lists.osgeo.org
> http://lists.osgeo.org/mailman/listinfo/grass-user
> 
> 

Dear Jarek,

I am trying to use r.area, but with no success.
I have a raster ("my_raster") that contains either the value 255 or 0. So
first I used r.clump to create unique categories:

r.clump input=my_raster output=my_raster_clumped

And then I used r.area like this:

r.area input=my_raster_clumped output=my_raster_area

But then I get the following error:

ATENÇÃO: Raster map <my_raster_clumped> not found in mapset
           <my_raster_clumped>
ERRO:<my_raster_clumped> is not of type CELL, probably not crated with
     r.clump

The result of r.info for the clumped raster is:


+----------------------------------------------------------------------------+
 | Layer:    my_raster_clumped              Date: Sat Jun 19 20:23:45 2010   
|
 | Mapset:   ATLANTIC                       Login of Creator: marcello       
|
 | Location: GEBCO_MERCATOR                                                  
|
 | DataBase: /home/marcello/grassdata                                        
|
 | Title:    clump of <my_raster at ATLANTIC> ( my_raster_clumped )             
|
 | Timestamp: none                                                           
|

|----------------------------------------------------------------------------|
 |                                                                           
|
 |   Type of Map:  raster               Number of Categories: 26             
|
 |   Data Type:    CELL                                                      
|
 |   Rows:         296                                                       
|
 |   Columns:      326                                                       
|
 |   Total Cells:  96496                                                     
|
 |        Projection: Mercator                                               
|
 |            N:    3948000    S:    3652000   Res:  1000                    
|
 |            E:   -7037000    W:   -7363000   Res:  1000                    
|
 |   Range of data:    min = 1  max = 26                                     
|
 |                                                                           
|
 |   Data Description:                                                       
|
 |    generated by r.clump                                                   
|
 |                                                                           
|
 |                                                                           
|

+----------------------------------------------------------------------------+

The usage is so simple and the error is so nonsense that I have no clues of
what may be happening. Any ideas?

Best regards,
Marcello.

P.S.: By the way, thank you for the fuzzy modules. They made my life much
easier.






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