[GRASS-dev] patch for v.voronoi/v.delaunay

Hamish hamish_b at yahoo.com
Wed Apr 23 02:36:34 EDT 2008


Michael Barton wrote:
> Is there anyway to display a TIN in 3D with GRASS? In NVIZ, it just
> looks like a Delaunay triangulation network unless there is something
> I'm not doing.

Make sure your 3D triangulation output "Map is 3D".

AFAIK faces will always be based on a single color (some todo).



off on a tangent:
As I've ranted on about before, TINs are really just the point data that
define them, so in general you'd be much better off extracting the points
and using a real interpolation module like v.surf.rst to make a surface
from those points.  The exception is from e.g. the poster the other day
who's point data was not uniformly distributed, density increased by
orders of magnitude as you get nearer to an object of interest (dynamic
computational mesh size)
 e.g.  http://gfs.sourceforge.net/examples/examples/tangaroa.html

v.surf.rst does the same sort of thing during processing for no-data
search areas, but the final product there is at the region resolution.
The problem the poster the other day had was that the overall grid at a
resolution appropriate for the coastal areas would make a massive array
when extended to include the oceanic data, and you probably have to make
a number of maps each as a different scale.


I remember in the past when talking about the GRASS 7 raster format it
was mentioned that perhaps Adaptive JPEG-like blocks could be used to
save the data instead of row-by-row. This is slightly a perversion of
that, but an interesting problem to think about.



Hamish




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