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

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

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
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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@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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Jarek Jasiewicz wrote:

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.

it is a little unclear to me, could you describe how this is
different from what r.report and r.stats do?

Also allow remove small areas with size lower than treshold.

nice. what are they replaced with, nulls?

regards,
Hamish