I need to convert a vector contour map to a raster so I can apply the
hydrologic models modules.
Reading the v.to.rast manual page I learned that I needed to add categories
to the input contour map. Running v.category added no categories: "0
features added."
v.info does not tell me anything about the elevation values of the contour
lines. Looking at the v.* modules, and trying v.univar, didn't help. I could
try v.to.3d, but I need information about the vector map's contents.
Which v.db* should I use to find the elevation colum associated with each
contour line?
TIA,
Rich
On Wed, 10 May 2023, Rich Shepard wrote:
Which v.db* should I use to find the elevation colum associated with each
contour line?
Long ago I used the GUI and it had a menu to examine the vector map's table.
Now, I just leared that v.db.select will work. There're more columns than I
need, but one does have the elevation data. Back to work ...
Rich
I think you need to interpolate and not simply convert vector lines to
raster lines. Make sure lines have an attribute with elevation (or z
coordinate) and use e.g. v.surf.rst module.
Māris.
trešd., 2023. g. 10. maijs, plkst. 17:29 — lietotājs Rich Shepard
(<rshepard@appl-ecosys.com>) rakstīja:
I need to convert a vector contour map to a raster so I can apply the
hydrologic models modules.
Reading the v.to.rast manual page I learned that I needed to add categories
to the input contour map. Running v.category added no categories: "0
features added."
v.info does not tell me anything about the elevation values of the contour
lines. Looking at the v.* modules, and trying v.univar, didn't help. I could
try v.to.3d, but I need information about the vector map's contents.
Which v.db* should I use to find the elevation colum associated with each
contour line?
TIA,
Rich
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On Wed, 10 May 2023, Maris Nartiss wrote:
I think you need to interpolate and not simply convert vector lines to
raster lines. Make sure lines have an attribute with elevation (or z
coordinate) and use e.g. v.surf.rst module.
Māris.
Interpolating the vector contour file before rasterizing makes sense to me,
too. Never before having to convert a vector elevation contour file to a
raster file I'd no idea which v.surf.* module to apply.
The vector file has a ContourEle attribute with the elevation values.
I'm taking your advice and will use v.surf.rast.
This project has more topography data issues than any I've encountered since
I started using grass with version 4.0 (all integer, all CLI.)
Very much appreciated,
Rich
Hi,
In addition, here is an overview page:
https://grasswiki.osgeo.org/wiki/Interpolation
Markus
On Wed, May 10, 2023 at 8:16 PM Maris Nartiss <maris.gis@gmail.com> wrote:
I think you need to interpolate and not simply convert vector lines to
raster lines. Make sure lines have an attribute with elevation (or z
coordinate) and use e.g. v.surf.rst module.
Māris.
trešd., 2023. g. 10. maijs, plkst. 17:29 — lietotājs Rich Shepard
(<rshepard@appl-ecosys.com>) rakstīja:
>
> I need to convert a vector contour map to a raster so I can apply the
> hydrologic models modules.
>
> Reading the v.to.rast manual page I learned that I needed to add categories
> to the input contour map. Running v.category added no categories: "0
> features added."
>
> v.info does not tell me anything about the elevation values of the contour
> lines. Looking at the v.* modules, and trying v.univar, didn't help. I could
> try v.to.3d, but I need information about the vector map's contents.
>
> Which v.db* should I use to find the elevation colum associated with each
> contour line?
>
> TIA,
>
> Rich
>
>
> _______________________________________________
> grass-user mailing list
> grass-user@lists.osgeo.org
> https://lists.osgeo.org/mailman/listinfo/grass-user
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--
Markus Neteler, PhD
https://www.mundialis.de - free data with free software
https://grass.osgeo.org
https://courses.neteler.org/blog
On Wed, 10 May 2023, Markus Neteler wrote:
In addition, here is an overview page:
https://grasswiki.osgeo.org/wiki/Interpolation
Markus,
Thanks very much. I'm learning many new things on this project and still
need to meet regulator's deadlines.
Much appreciated,
Rich
On Wed, 10 May 2023, Rich Shepard wrote:
Thanks very much. I'm learning many new things on this project and still
need to meet regulator's deadlines.
Markus,
The wiki page on 'Contour lines to DEM' is what I need.
Best regards,
Rich