We are trying to create an elevation raster map from
a paper contour map. The original map is in feet; we want the
final product in meters. I would think that the following
procedure would work:
1) Digitize paper map using v.digit and label contours
in feet.
2) Convert the digitized map to a rasterized contour map.
3) Run r.surf.contour to fill in the rasters between contours.
4) Use r.mapcalc to convert from feet to meters.
At step #3, however, we are getting a map that is "filled in"
but not interpolated; i.e. there is a green band for elevation 672, a light
blue band for elevation 674, etc., but nowhere is there an interpolated
673, for example. Is there a better way? What's the difference between
r.surf.contour and r.surf.idw? Is there anything to be gained by converting
the rasterized contour map to a sites file? If so, how does one do this --
I don't see an 'r.to.sites' or something similar in the manual.
Thanks for any advice.
Sharyl Walker
University of Illinois
guernsey@holstein.age.uiuc.edu