[GRASSLIST:2555] Re: Profiles using contour vector lines

Andrea Aime aaime at libero.it
Fri Oct 5 04:21:48 EDT 2001

Well, it can be done with available capabilities, but only if you're willing
to use the C vector API. First create the line as a vector, then use v.patch
to merge with the contour lines (maybe you will also need to run v.spag,
not sure here), then follow the line from node to node with the C api...
but you'll have to give the line a unique indentifier in order to
recognize it after the merge. You can find references to the C api in
the Grass Developer's manual, and also having a look at GRASS sources...
Hope this helps
Best regards
Andrea Aime

PS: althought slower, an interpolation with splines and the r.profile
should be more accurate than using linear segments between contour
lines... just my 1 cent...

----- Original Message -----
From: <spoedniek at f2s.com>
To: <grasslist at baylor.edu>
Sent: Friday, October 05, 2001 9:41 AM
Subject: [GRASSLIST:2554] Profiles using contour vector lines

> Hi,
> I need some suggestions on creating a profile using vector objects
> lines), rather than raster DEMs. Are there any functions in GRASS that I
can use
> for this?
> I wrote a script for this using a commercial GIS package (TNTmips from
> MicroImages), but would like to do it in GRASS. The process I used in the
> was to merge the contour line vector object with the line along which the
> profile is to be drawn and then to follow this line from node to node
> the elevation from the contour lines attached to each node. I know GRASS
> yet have all the vector functionality that most vector based GIS packages
> but perhaps someone has been working on something similar? I am quite new
> GRASS and have not checked out all the functions.
> Best regards,
> Henry
> -------------------------------------------------
> Everyone should have http://www.freedom2surf.net/

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