# [GRASS-user] measuring area on a 3d polygon

maning sambale emmanuel.sambale at gmail.com
Wed Nov 16 22:12:31 EST 2011

```Thanks, will try this.

On Thu, Nov 17, 2011 at 3:41 AM, Benjamin Ducke <benducke at fastmail.fm> wrote:
> I think Michael's reply (see below) to my message is
> actually the answer to your question ;)
>
> Ben
>
> On Wednesday, November 16, 2011 10:13 AM, "Michael Barton"
> <michael.barton at asu.edu> wrote:
>> r.surf.area
>>
>> will calculate a topographically corrected area for rasters. So if you
>> convert your vector areas to raster, this will do the trick.
>>
>> Michael
>> ______________________________
>> C. Michael Barton
>> Director, Center for Social Dynamics & Complexity
>> Professor of Anthropology, School of Human Evolution & Social Change
>> Arizona State University
>> Tempe, AZ  85287-2402
>> USA
>>
>> voice:  480-965-6262 (SHESC), 480-727-9746 (CSDC)
>> fax:          480-965-7671(SHESC), 480-727-0709 (CSDC)
>> www:    http://csdc.asu.edu, http://shesc.asu.edu
>>               http://www.public.asu.edu/~cmbarton
>>
>
> --
> Benjamin Ducke
> {*} Geospatial Consultant
> {*} GIS Developer
>
>  benducke at fastmail.fm
>
>
> On Wednesday, November 16, 2011 11:01 AM, "maning sambale"
> <emmanuel.sambale at gmail.com> wrote:
>> Hi,
>>
>> I have a series polygons located in a mountainous terrain.  I can
>> convert the 2d vector into 2.5d using v.drape and a DEM, however, it
>> only converts 2D vector point or line data and not areas.  My task is
>> to calculate the area in hectares of the polygon incorporating the
>> elevation/surface of the polygon.  I then need to subdivide the main
>> polygon into smaller polygons using a preferred area in hectares.
>>
>> How to calculate 2.5d polygon areas in grass?
>>
>> --
>> cheers,
>> maning
>> ------------------------------------------------------
>> "Freedom is still the most radical idea of all" -N.Branden
>> wiki: http://esambale.wikispaces.com/
>> blog: http://epsg4253.wordpress.com/
>> ------------------------------------------------------
>> _______________________________________________
>> grass-user mailing list
>> grass-user at lists.osgeo.org
>> http://lists.osgeo.org/mailman/listinfo/grass-user
>>
> _______________________________________________
> grass-user mailing list
> grass-user at lists.osgeo.org
> http://lists.osgeo.org/mailman/listinfo/grass-user
>

--
cheers,
maning
------------------------------------------------------
"Freedom is still the most radical idea of all" -N.Branden
wiki: http://esambale.wikispaces.com/
blog: http://epsg4253.wordpress.com/
------------------------------------------------------
```