What, no takers? Just a Yes or No will be already of great help to me,
anything more, like some hint on a possible solution would be cream on top.
Thanks all the same for reading this.
George
georgew wrote:
Hi, I am totally new to GRASS and overwhelmed by its scope and not sure
whether the following is possible:
I have a set of topographic maps in shapefile format containing contours
and walking tracks. The track data does not include elevation (only lat.
and long.), but the contour lines do include elevation. Is it possible
(and how?) to create an elevation profile for the length of the walking
track using the intersecting points between the track and the contour
lines to obtain the elevation values?
Many thanks for any assistance you can give me.
George
Dude- It is saturday night. Your request is for a fairly simple
operation, but there are several steps.
Some hints:
1. convert your contours into a DEM:
v.surf.rst
2. sample the elevation model along your line segments:
v.to.db
v.drape
you may need to densify the line segments-- i.e. add more vertices
along each line segment. if you need to do this, run v.segment before
either of the above two commands.
Also check the mailing list archives.
Cheers,
Dylan
On Sat, Nov 29, 2008 at 10:21 PM, georgew <gws293@hotmail.com> wrote:
What, no takers? Just a Yes or No will be already of great help to me,
anything more, like some hint on a possible solution would be cream on top.
Thanks all the same for reading this.
George
georgew wrote:
Hi, I am totally new to GRASS and overwhelmed by its scope and not sure
whether the following is possible:
I have a set of topographic maps in shapefile format containing contours
and walking tracks. The track data does not include elevation (only lat.
and long.), but the contour lines do include elevation. Is it possible
(and how?) to create an elevation profile for the length of the walking
track using the intersecting points between the track and the contour
lines to obtain the elevation values?
Many thanks for any assistance you can give me.
George
What, no takers? Just a Yes or No will be already of great help to me,
Yes.
I think you should be looking at converting the shapefile contour lines to a raster, then make an elevation surface from that, and use the r.profile module to calculate elevation profiles for the track lines. So:
v.in.org to import the contour lines and tracks into grass
v.to.rast and r.thin to convert the contour lines to a raster map.
r.surf.contour to create an elevation surface from the rasterized contours
r.profile to get the elevations along the tracks.
Post back with specific questions if you hit a snag.
Regards,
Micha
anything more, like some hint on a possible solution would be cream on top.
Thanks all the same for reading this.
George
georgew wrote:
Hi, I am totally new to GRASS and overwhelmed by its scope and not sure
whether the following is possible:
I have a set of topographic maps in shapefile format containing contours
and walking tracks. The track data does not include elevation (only lat.
and long.), but the contour lines do include elevation. Is it possible
(and how?) to create an elevation profile for the length of the walking
track using the intersecting points between the track and the contour
lines to obtain the elevation values?
Many thanks for any assistance you can give me.
George
You can also take a look at new vector addon module v.profile. It will
give Your track intersections with contour lines or any other
points/lines. Currently it has limitation - Your track has to be a
single vector line. You can also combine r.profile and v.profile to
create better track profiles (i.e. use r.profile for elevation and
v.profile to get crossings with various vector layers like revers,
roads etc.).
Also, as most (all?) list members are volunteers, it may happen, that
nobody has time to write an answer. Reading GRASS documentation is a
great way how to spend Your time till somebody answers Your problem.
WBR,
Maris.
2008/11/30, Micha Silver <micha@arava.co.il>:
georgew wrote:
What, no takers? Just a Yes or No will be already of great help to me,
Yes.
I think you should be looking at converting the shapefile contour lines to a
raster, then make an elevation surface from that, and use the r.profile
module to calculate elevation profiles for the track lines. So:
v.in.org to import the contour lines and tracks into grass
v.to.rast and r.thin to convert the contour lines to a raster map.
r.surf.contour to create an elevation surface from the rasterized contours
r.profile to get the elevations along the tracks.
Post back with specific questions if you hit a snag.
Regards,
Micha
anything more, like some hint on a possible solution would be cream on
top.
Thanks all the same for reading this.
George
georgew wrote:
Hi, I am totally new to GRASS and overwhelmed by its scope and not sure
whether the following is possible:
I have a set of topographic maps in shapefile format containing contours
and walking tracks. The track data does not include elevation (only lat.
and long.), but the contour lines do include elevation. Is it possible
(and how?) to create an elevation profile for the length of the walking
track using the intersecting points between the track and the contour
lines to obtain the elevation values?
Many thanks for any assistance you can give me.
George
Hello Georg,
first - I suggest You to get a copy of GRASS book. It's really good
reading for beginner.
Second - as I noted, v.profile is a new GRASS Add-on [1]. You can
compile it from source only. It requires GRASS 6.4 or 7 (both
unreleased). v.profile README file contains short note how to install
it.
"segmentation faults" on recent Ubuntu version(s?) is a known issue.
IIRC best solution was recompiling GRASS and GDAL from source... You
can search trac and ML archive to see more.