3D Interpolation using point cloud in GRASS GIS

Question

I've imported a set of 3D points (z,y,z) into GRASS GIS. I'm having trouble: a) visualising my dataset in 3D using nviz or the standard data viewer (I can only get a 2D plan view of my data) and, b) interpolating them into a solid 3D voxel object. My dataset is pretty straightforward and there's only 1520 points.

The GRASS user interface is not that user friendly and I can't find a suitable tutorial to follow. Any ideas or pointers would be very much appreciated. I'm sure I should be using the v.vol.rst tool, but when I input my parameters, I get the following error message: ERROR: Column type of wcolumn is not supported (must be integer or double).

Any ideas?

Answer 1

Do you want to achieve something like this (my office is in the center)?

As Mihai sais, it is not a 3D interpolation. Consider to check http://grasswiki.osgeo.org/wiki/LIDAR and http://grasswiki.osgeo.org/wiki/Interpolation . It is a surface interpolation. r.in.xyz will do most of it, followed by v.surf.rst or v.surf.bspline, see Wiki tutorials.

Answer 2

You should check the Create 3D output option (-z flag) while importing, so to be sure you get a 3D vector. This will assure that you get the 3D viewing.

v.vol.rst require beside z column, also a column storing what you need to inteprolate (temperature, concentrations from drilling holes). That's why you get error on wcolumn.

If your dataset is not real 3D (being a tridimensional surface rather than a tridimensional volume), use instead v.surf.rst or v.surf.rst

Mihai