> Tomas Lanczos wrote:
>> I have contour maps converted to rasters (rock temperatures) in
>> different depths (-500, -1000, -1500, -2000, -2500, -3000, -4000, -6000
>> meters below sea level). What is the best way to interpolate them to one
>> 3d raster (volume)?
Hamish wrote:
> for evenly spaced raster slices first set the 3D region, e.g.
> g.region t=-500 b=-6000 tbres=500
>
> then use the r.to.rast3 module to make the 3D raster volume map.
>
> but you would need to interpolate intermediate levels for missing slices.
> For -3500 you could use r.series method=average, for 4500,5000,5500 you
> would have to use r.mapcalc manually.
>
> v.vol.rst could be used to interpolate from 3D points, but RST+contour
> lines usually is prone to artifact problems do to the uneven spatial
> distribution of data points.
>
> see also the 3D help page on the wiki site:
> http://grass.gdf-hannover.de/wiki/Help_with_3D
Tomas wrote:
I experimented a lot with this, Your way described below was the easiest
and fastest but the result is not very satisfying for me becasue the
produced "stripes" in the vertical slices (see the picture).
If you look at just the -500, -1000, -1500, -2000, -2500, -3000 slices you
have, with no r.series interpolation, do you see the stripe? If 0 is the top,
it looks like the -2500m values are misplaced??
Also if you are just doing a linear interpolation you can use r.series in
multiple passes instead of r.mapcalc, first calculate -5000 from average or
-4000 and -6000 maps, then take average of new -5000 and -4000 for -4500 map,
etc. Maybe less chance to go wrong then.
You can do a slide show of the slices, with d.slide.show, xganim, or the new
Tcl animation program in 6.3. Find the min/max range of all the maps and then
set & use common color rules for all maps.
I also tried to extract points using r.random (3%), and interpolate using
v.vol.rst but after 12 hours of computing and reaching approx. 20% I
gave it up. What is the best optimalization method for interpolation in
v.vol.rst?
Lower XY resolution? Or just leave it running over the weekend..
Hamish
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