Newsgroups: info.grass.user
Path: zorro.cecer.army.mil!shapiro
From: shapiro@zorro.cecer.army.mil (Michael Shapiro)
Subject: Re: rasterizing digitized contour maps
Message-ID: <C3I6Ko.99y@news.cecer.army.mil>
Sender: news@news.cecer.army.mil (Net.Noise owner)
Organization: US Army Corps of Engineers Construction Engineering Research Labs
References: <9302251602.AA01823@cotopaxi.hwr.arizona.edu>
Date: Sun, 7 Mar 1993 05:14:48 GMT
Lines: 39
In <9302251602.AA01823@cotopaxi.hwr.arizona.edu> bobh@hwr.arizona.edu (Bob Harrington) writes:
r.surf.idw or r.sruf.idw2 use inverse-distance-squared weights to form
average elevation. Generaly this a NOT a good method for surface generation.
These tools are much faster than those in 3.1. No telling how long, but
they take their time. You should expore the new s.sruf.tps which has
a superior model for DEMs from point data.
I imagine some of you have done this before:
I have a digitized contour map that I want
to turn into a DEM. I rasterized the contours
with v.to.rast, which worked fine, and now want
to interpolate all the cells between the contours.
I am trying to use r.surf.idw2 to do this,
but I have two questions:
1. Is this the best way to do this? I expect
some strange results using r.surf.idw2, because
for cells near a contour, all the nearest cells
used in the interpolation will have the same
value, so the interpolated cell will just be
assigned the same value as the nearby contour.
2. I launched r.surf.idw2 yesterday on a SPARC 10,
and it is still working this morning. The map is
834 by 989. How long is this going to take?
Cheers,
Bob Harrington
Hydrology and Water Resources
University of Arizona
--
Michael Shapiro U.S. Army CERL
Environmental Division