Using r.cost, but roads ignore contours.
cameron at stl.dec.com
Tue Oct 7 20:10:50 EDT 1997
Scott O'Donnell wrote:
> If you need the contour vector layer to be used by r.cost, you'll
> need to "rasterize" your vector contour layer. Use the raster
> contour map as input to r.cost, then r.cost will "follow" the path
> you expected to get.
I'm not sure if you read my mail fully, Scott. The input data was a
raster layer derived from the vector contour layer. I used v.to.rast
for that, and then smoothed it with r.neighbors. Then I used
r.slope.aspect to derive a slope raster layer.
> From what I see, your image includes two elements, a gray-scale
> elevation raster map and a vector contour map.
No, the image in my mail was three elements, a grey-scale cost raster
which was generated by r.cost, the vector contour map, and the vector
generated by an r.drain. My original mail explained the sequence used.
I've examined the program code in r.cost, and I _know_ it takes no
notice of the angle of attack of a path. So is there a program for
creating a path that does take direction of traversal into account?
James Cameron (cameron at stl.dec.com)
Digital Equipment Corporation (Australia) Pty. Ltd. A.C.N. 000 446 800
More information about the grass-user