[GRASS-user] measuring distance along a line

[Michael Barton]

Something that just struck me. You might well be able to get some
reasonabley accurate information on this simply by running r.profile. It
will output cumulative distance along a line--specified by a series of xy
points--along with the value of a raster (e.g., elevation) at each point.

Michael


On 5/16/07 1:42 AM, "Ronja Düffel" <dueffel at informatik.uni-frankfurt.de>
wrote:

> 
> Thanks for the fast reply, I'll try your suggestion and report back to the
> list.
> 
> Ronja 
> 
> 
> 
> Am Dienstag, 15. Mai 2007 13:13 schrieben Sie:
>> Ronja Düffel wrote:
>>> is there a possibility to measure distance along a line in grass?
>> 
>> yes.
>> 
>>> I have a map of a river system and I have points (given by Northing
>>> and Easting) where rivers con- or diverge. Now I would like know the
>>> distance between those points, measured along the course of the
>>> river. Is there a possibility to do that in grass without having to
>>> measure the distance by hand (i.e. using the measuring tool in the
>>> display window)?
>> 
>> Beware that this is a fractal problem and the answer is dubious!
>> 
>> 
>> maybe something like:
>> 
>> v.clean in=rivers out=river_lines tool=break
>> v.db.addcol river_lines column="seg_length DOUBLE PRECISION"
>> v.to.db river_lines option=length column=seg_length units=me
>> 
>> d.vect river_lines disp=shape,attr attrcol=seg_length
>> 
>> 
>> you might also look at v.segment and v.lrs.*
>> 
>> 
>> Hamish
> 
> 

__________________________________________
Michael Barton, Professor of Anthropology
School of Human Evolution & Social Change
Center for Social Dynamics and Complexity
Arizona State University

phone: 480-965-6213
fax: 480-965-7671
www: http://www.public.asu.edu/~cmbarton