[Gvsig_english] QUESTION gvSIG 1.9 (BN 1253) -- Establish aspect and slope of an area based on contour lines?

[Simon Cropper]

Fran,

Thank you. I managed all except # 2. I tried this and it worked
beautifully.

Cheers Simon

        Simon Cropper
        Botanicus Australia Pty Ltd
        P.O. Box 160 Sunshine VIC 3020
        P: 03 9311 5822. M: 041 830 3437.
        E: scropper at botanicusaustralia.com.au
        W: http://www.botanicusaustralia.com.au


On Tue, 2010-03-30 at 11:07 +0200, Francisco José Peñarrubia wrote:

> Hi Simon.
> 
> The answer is yes, you can (Obama joke) ;-)
> 
> You will use Sextante tools + Geoprocess tool.
> 
> This is a short summary:
> 
> 1.- Rasterize your contours shape. Sextante -> Rasterization and 
> interpolation -> Rasterize Vectorial layers. Choose the field name that 
> contains Elevation data. Remember to choose a good extent and a suitable 
> cell size.
> 2.- Now, time to interpolate. And easy method (you can also choose 
> Krigging, but probable is enough with Sextante -> Basic tools por raster 
> layers -> Void filling
> 3.- If you need slope, use Sextante -> Geomorphometry and terrain analysis
> 
> After that, you will have an MDT and a slope raster. The next steps are 
> to crop this MDT with your polygon layer (parcels, for example), convert 
> this raster to points and assign average slope or altitude to this polygons.
> 
> 4.- Sextante-> Basic tools for raster layers -> Crop grid with polygon layer
> 5.- Sextante -> Vectorization -> Raster layer to points layer.
> 6.- View -> Geoprocess toolbox -> Analysis -> Spatial join => choose 
> input cover your polygon layer and clip cover you point layer (I know, 
> the name are confusing the user...). When you click in OK, a window 
> appears. Choose slope or altitude and click in central button. Choose 
> average. Then click yes to the questions and you should have a polygon 
> layer with average slope or altitude, depending on wich raster layer you 
> choose (MDT or slope).
> 
> Hope it helps.
> 
> Best regards.
> 
> Fran Peñarrubia
> www.scolab.es
> 
> PS: (Excerpt from ENOSAT course :-) ).
> 
> Simon Cropper escribió:
> > Hi,
> >
> > I have a shapefile showing contours across a region.
> >
> > Visual inspection of the vector data suggests that various subregions 
> > have different aspects/bearings and slope.
> >
> > Is there a way using gvSIG or any of its plugins to visualize or 
> > categorize this data?
> >
> > My desired output would be a polygon file with the attribute field 
> > aspect/bearing and slope.
> >
> > -- 
> >
> > Cheers Simon
> >
> > Simon Cropper
> > Botanicus Australia Pty Ltd
> > PO Box 160, Sunshine, Victoria 3020.
> > P: 9311 5822. M: 041 830 3437.
> > mailto: scropper at botanicusaustralia.com.au 
> > <mailto:scropper at botanicusaustralia.com.au>
> > web: www.botanicusaustralia.com.au <http://www.botanicusaustralia.com.au>
> >
> >
> >
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