Hello, I’ve imported a vector of points into GRASS - it’s approximately a grid with ~24k points according to GRASS. I’m trying to interpolate it, but what ever methods I try (v.surf.idw or v.surf.bspline), the resulting raster is just one point, approximately in the middle of the grid with the average value of the z values.
I am able to see the points rendered as a vector field, so the data looks like it’s been imported correctly, but I can’t figure out this interpolation step.
Thanks!
If your vector points are already on a grid, you can simply use v.to.rast for conversion.
In every case, check your region. It defines the extent and resolution of the raster you want to create. Check for g.region in the manual. g.manual -p in the command line prints your current settings.
Christian Kaiser
On 9 janv. 2010, at 20:34, James Kebinger wrote:
Hello, I've imported a vector of points into GRASS - it's approximately a grid with ~24k points according to GRASS. I'm trying to interpolate it, but what ever methods I try (v.surf.idw or v.surf.bspline), the resulting raster is just one point, approximately in the middle of the grid with the average value of the z values.
I am able to see the points rendered as a vector field, so the data looks like it's been imported correctly, but I can't figure out this interpolation step.
Thanks!_______________________________________________
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Is your region set to the extent of the vector points?
Is the right attribute column being spicified to interpolate?
Mark
On Jan 9, 2010, at 2:34 PM, James Kebinger <jkebinger@gmail.com> wrote:
Hello, I've imported a vector of points into GRASS - it's approximately a grid with ~24k points according to GRASS. I'm trying to interpolate it, but what ever methods I try (v.surf.idw or v.surf.bspline), the resulting raster is just one point, approximately in the middle of the grid with the average value of the z values.
I am able to see the points rendered as a vector field, so the data looks like it's been imported correctly, but I can't figure out this interpolation step.
Thanks!_______________________________________________
grass-user mailing list
grass-user@lists.osgeo.org
http://lists.osgeo.org/mailman/listinfo/grass-user
It turned out the resolution of my region was set to 1 - presumably that’s in degrees, so that wasn’t enough. Moved it down to 0.001 or so and getting better results. Thanks everyone.
On Sat, Jan 9, 2010 at 2:34 PM, James Kebinger <jkebinger@gmail.com> wrote:
Hello, I’ve imported a vector of points into GRASS - it’s approximately a grid with ~24k points according to GRASS. I’m trying to interpolate it, but what ever methods I try (v.surf.idw or v.surf.bspline), the resulting raster is just one point, approximately in the middle of the grid with the average value of the z values.
I am able to see the points rendered as a vector field, so the data looks like it’s been imported correctly, but I can’t figure out this interpolation step.
Thanks!