[GRASS-user] 3D Buildings

[Hamish]

cheg01 wrote:
> faces are to be understood as "3D areas", their centroids are "kernels".
> yes, v.extrude generates only faces

One thing I have never understood: do kernels live on the surface of a 2D plane
in 3D space (so 6 per cube), or inside a volume (the center of a sphere)?

> > I tried extruding both
> >  with and without the "trace" flag set.
Jachym wrote:
> this only causes, that the "roofs" of building will "copy" the
> elevation. Otherwise, they remain flat.


going back to the earlier thread, I had an idea to remove buildings from the
LIDAR raster data. Make a slope map, set anything with >60-80 degree slope as
NULL. (take away the walls) Next use r.cost starting on known land to isolate
the roofs which do not touch the land, use the cost map as a MASK and make a
layer with only land. Then use r.fillnulls or similar to interpolate over the
holes leaving a elevation surface with no buildings.

?


Hamish


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