[GRASS-user] elevation profile

[John C. Tull]

Hi John,

You will likely get a more complete answer from others, but you seem to be on the right track with v.drape. From there, you can add a column for cumulative length with v.db.addcol, then run v.to.db with option=length to add a length column to your 3d vector. You might be able to subsample from there.

Another possibility would be to run v.segment to generate points at your desired length interval for the original vector. Then you could run v.drape on the resulting points file and work from there or somehow pipe the point coordinates into r.profile.

Good luck,
John

On Jul 15, 2010, at 12:25 PM, John Callahan wrote:

> Hopefully a quick question that I'm struggling with.  (I'm a long-time GIS user but trying to move my work to GRASS and other FOSS4G.)   I'm using GRASS 6.4 RC6 on Windows XP.
> 
> I have a raster grid representing elevation at 2meter resolution. I have a line shapefile representing roads (about 20 roads total).  I would like to get ASCII text files of x,y,z at about 1 or 2 meter intervals along each road.  Any ides of what I can try?
> 
> I thought v.drape might work. This converts my 2D road shapefile to 3D, but I'm not sure where to go from there.  And this doesn't help getting 1 or 2 meter intervals.  I also tried r.profile but this requires input as a listing of x,y coordinates, not shapefiles.  I know there's a step here I'm missing.
> 
> - John
> 
> **************************************************
> John Callahan, Geographic Information Scientist
> Delaware Geological Survey, University of Delaware
> URL: http://www.dgs.udel.edu
> **************************************************
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