[GRASS-user] Moebius strip to illustrate 3D vector capabilities

Hamish hamish_nospam at yahoo.com
Wed May 30 12:36:55 EDT 2007

Markus Neteler wrote:
> > > I just made this screenshot
> > > http://grass.itc.it/grass63/screenshots/vector.php
> > > to illustrate GRASS' 3D vector capabilities. Not
> > > sure if you can do the same with other GIS :-)
> I would love to see the Escher ants:
> http://www.nature.com/nature/journal/v426/n6968/images/426776a-f1.2.jpg
> With v.in.dxf (of ants or whatever) and v.transform and a rainy day it
> shouldn't be too hard!

some notes:

most DXF download sites I looked at were useless for-profit black holes.

but then I found a very nice collection of 3D vector meshes:

In a nice well documented & cleaned mesh format. yay .edu.

rather than write a nice mesh -> grass 3D vector face converter, I went
quick & dirty and downloaded the 3d studio versions (.3ds) and converted
them to DXF before importing with v.in.dxf.

To convert .3ds -> .dxf I used wcvt2pov.exe in wine. It worked pretty
well, nice simple program.

I also tried 3dto3dV35.zip; the obfuscated linux version compiled, but
I think it has some dirsep errors or something (and little way to tell).

there is a .rpm version, maybe that's better?

I gave up and ran the 3dto3d.exe version in wine.
   (in .wine/config change x11 to ttydrv)
command line for that looked like:
 wine ../3dto3d.exe polyline.obj /if6 /iv /d"polyline.dxf" /of13 /ov /ol1 /om1
 wine ../3dto3d.exe face.obj /if6 /iv /d"face.dxf" /of13 /ov /ol1 /om0

wcvt2pov.exe was less painful for sure.

then, in GRASS,
 v.in.dxf in=cow.dxf out=cow
 g.region vect=cow
 r.mapcalc foo=1
 nviz foo
 [Raster Surface -> Transparency -> Max]
 [3d Polygons -> New]

see also


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