[GRASS-user] areas

GRASS GRASS user
1

hi, I was wondering if it is posible to measure areas and distances inside GRASS, and save the values in a table.

wich commands do I have to use?
thank you

Isabel

2

Hi,

2008/4/11, Isabel Alfaro Cardozo <isabelalfaro@gmail.com>:

hi, I was wondering if it is posible to measure areas and distances inside
GRASS, and save the values in a table.

if you mean areas of polygons and length of linear feature you can use
v.to.db module. For distance measuring use d.measure or GUI tool.

Martin

--
Martin Landa <landa.martin gmail.com> * http://gama.fsv.cvut.cz/~landa *

3

On 11/04/08 14:42, Isabel Alfaro Cardozo wrote:

hi, I was wondering if it is posible to measure areas and distances inside GRASS, and save the values in a table.

wich commands do I have to use?

This depends whether you work in raster or vector, but in vector look at the following:

v.to.db
v.distance

For raster maps you should check out

r.distance
r.stats (possible with r.clump)

Moritz

thank you

Isabel

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4

On Sat, 2008-04-12 at 08:12 +0000, Isabel Alfaro Cardozo wrote:

hi, I was wondering if it is posible to measure areas and distances
inside GRASS, and save the values in a table.

wich commands do I have to use?
thank you

Isabel

2 more examples for categorised raster maps (in this case I have a
fragment of the GLC2000 land cover map):

r.report -nh glc2000_areas units=h

+-----------------------------------------------------------------------------+
| Category Information | |
| #|description | hectares|
|-----------------------------------------------------------------------------|
| 2|Tree Cover, broadleaved, deciduous, closed . . . . . . . . . . |
1300.00|
| 4|Tree Cover, needle-leaved, evergreen . . . . . . . . . . . . . |
46,000.00|
| 6|Tree Cover, mixed leaf type. . . . . . . . . . . . . . . . . . |
16,500.00|
|11|Shrub Cover, closed-open, evergreen. . . . . . . . . . . . . . |
85,900.00|
|12|Shrub Cover, closed-open, deciduous. . . . . . . . . . . . . . |
600.00|
|16|Cultivated and managed areas . . . . . . . . . . . . . . . . . |
16,100.00|
|-----------------------------------------------------------------------------|
|TOTAL |166,400.00|
+-----------------------------------------------------------------------------+

-

r.stats -an glc2000_areas

r.stats: 100%
2 13000000.000000
4 460000000.000000
6 165000000.000000
11 859000000.000000
12 6000000.000000
16 161000000.000000

5

Isabel:

> hi, I was wondering if it is posible to measure areas and distances
> inside GRASS, and save the values in a table.

Martin:

if you mean areas of polygons and length of linear feature you can use
v.to.db module. For distance measuring use d.measure or GUI tool.

see also the m.distance script using Python/SWIG:
(non-interactive backend module; takes a series of coords)
  http://trac.osgeo.org/grass/browser/grass/trunk/swig/python/examples/

both d.measure (middle click) and m.distance will report area too.
see also d.where to get a list of coordinates to feed into a area
measurement tool or something like v.in.ascii or r.in.poly.

Hamish

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