I agree that v.report does a good job, but what is really needed is a
program that gives "on-the-ground" distance measurements; that is, takes in
to account rises and falls of elevation, so that we get TRUE distance
measurements, not just the distance along the smooth surface of an ellipsoid.
My friend Runxuan Zhao (rzhao@psupen.psu.edu) suggested to use r.volume
to get the distances of networks. To the "surface" distances, one may
consider the following:
. rasterize the streams (or roads);
. r.mapcalc 'surface resolution' using horizontal resolution, slope
and aspect, derived from elevation;
. r.volume the surface resolution.
***
Jianping Xu
Center for Remote Sensing and Spatial Analysis Email: jianp@ocean.rutgers.edu
Rutgers University Phone: (908) 932-9631
New Brunswick, NJ 08903-0231 Fax: (908) 932-8644