RE: [GRASS5] TINs as 3D vectors

There is no possibility of creating 3D-vectors from v.delaunay directly.
We are currently implementing a system for vague regions in GRASS that
uses triangulations with 3D vectors, and have linked Triangle to GRASS.
Triangle is a much faster and memory efficient delaunay triangulation
with support for constraints. See
http://www-2.cs.cmu.edu/~quake/triangle.html for more information.

As soon as everything is done we'll release a few useful GRASS modules,
including this better Delaunay triangulation and the 2D alpha-shape
algorithm, and perhaps some 2D visualization of TINs which might be
useful as a general module with some slight modifications. If you need
it now I can send you the module.

Regards,

Pieter Bos

-----Original Message-----
From: grass5-admin@grass.itc.it [mailto:grass5-admin@grass.itc.it] On
Behalf Of Jachym Cepicky
Sent: Wednesday, April 13, 2005 2:10 PM
To: GRASS Developers list
Subject: [GRASS5] TINs as 3D vectors

Hallo,
is there any possibilty, how to create 3D-vector of TIN (triangulated
irregular network) of the output from v.delauny? I have 3D points and
v.delauny makes only 2D-polygons from it..

I wrote some script which solves this, but before I post it, I would
like to know, that I did not something useless.

Thank you a lot

Jachym
--
Jachym Cepicky
e-mail: jachym.cepicky@centrum.cz
URL: http://les-ejk.cz
GPG: http://www.fle.czu.cz/~jachym/gnupg_public_key/

Triangle does not appear to have a clear license compatible with GPL:

"Please note that although Triangle is freely available, it is copyrighted by the author and may not be sold or included in commercial products without a license."

Am I wrong? If you want to include that to GRASS distribution, the library must have a license which gives at least the same rights as GPL.

Do you have a module for conversion from raster to TIN?

How do you store the data, do you use your format? Did you try to use GRASS format?

Radim

Pieter Bos wrote:

There is no possibility of creating 3D-vectors from v.delaunay directly.
We are currently implementing a system for vague regions in GRASS that
uses triangulations with 3D vectors, and have linked Triangle to GRASS.
Triangle is a much faster and memory efficient delaunay triangulation
with support for constraints. See
http://www-2.cs.cmu.edu/~quake/triangle.html for more information.

As soon as everything is done we'll release a few useful GRASS modules,
including this better Delaunay triangulation and the 2D alpha-shape
algorithm, and perhaps some 2D visualization of TINs which might be
useful as a general module with some slight modifications. If you need
it now I can send you the module.

Regards,

Pieter Bos

-----Original Message-----
From: grass5-admin@grass.itc.it [mailto:grass5-admin@grass.itc.it] On
Behalf Of Jachym Cepicky
Sent: Wednesday, April 13, 2005 2:10 PM
To: GRASS Developers list
Subject: [GRASS5] TINs as 3D vectors

Hallo,
is there any possibilty, how to create 3D-vector of TIN (triangulated
irregular network) of the output from v.delauny? I have 3D points and
v.delauny makes only 2D-polygons from it..

I wrote some script which solves this, but before I post it, I would
like to know, that I did not something useless.

Thank you a lot

Jachym
--
Jachym Cepicky
e-mail: jachym.cepicky@centrum.cz
URL: http://les-ejk.cz
GPG: http://www.fle.czu.cz/~jachym/gnupg_public_key/

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