topic Triangulated 3DS models in Collaboration with other software

Triangulated 3DS models

Anonymous — Mon, 16 Feb 2004 18:11:23 GMT

Why imported 3ds models in AC have more polygons than they should have? I give an example: Let say I import a 3DS cube, it has 6 faces (the 4 lateral sides plus up and down sides) but in AC it comes very triagulated resulting in much more polygons in it´s geometry. Why this occurs? Is there a way to reduce or stop the triangulate process? I tried importing them with Zoom GDL 2.1 but the same occurs.
There are so nice 3DS or MAX models available out there on the internet, they aren´t parametric like GDL but it would be nice to import them to our current work without increasing the number of polygons in a such way.
Any file sharing guru could help on this? Maybe Stefan?
Thanks,
Ricardo Borges

Re: Triangulated 3DS models

stefan — Tue, 17 Feb 2004 09:57:26 GMT

A cube in the 3D-world has 6 sides, but each Quad-side contains two triangles. Every geometry in 3D is eventually recalculated (triangulated) to triangles. This is expected behaviour.

3D-tools smooth the triangles and hide edges, so "real" polygons seem to appear. ArchiCAD is probably doing this as well. They do a good job of hiding the invisible edges, but they are there.

I guess that what you want: "untriangulate" the 3ds-mesh (or at least hide the unneeded edges) is not possible. Maybe when you can import OBJ-files (hah, that stopped working in ArchiCAD 8.x).

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Now for programming-guru's: maybe if you can import a custom mesh-format and you make a conversion tool for other software to export in that optimized format? This could be a (rather difficult) solution.

Re: Triangulated 3DS models

Anonymous — Tue, 17 Feb 2004 12:27:01 GMT

Thanks Stefan for your reply.
Let me see if I got you: Viz hides those edges of a model, they are there but invisible to us. AC doesn´t create more triangles it just shows all the hide edges. Is that right?

Well, I don´t care about looking at unneeded edges, I just don´t want the imported model to be heavier/bigger in AC than it should be.

Re: Triangulated 3DS models

stefan — Tue, 17 Feb 2004 12:33:28 GMT

Ricardo wrote:
Thanks Stefan for your reply.
Let me see if I got you: Viz hides those edges of a model, they are there but invisible to us. AC doesn´t create more triangles it just shows all the hide edges. Is that right?

Well, I don´t care about looking at unneeded edges, I just don´t want the imported model to be heavier/bigger in AC than it should be.

If you make a Cube in ArchiCAD using GDL it'll take very few data. If you make a cube in VIZ/max and import it into a GDL-library object, it will be much heavier.
(If you repeat this example with a sphere, the results will even be worse).

I never really import things into ArchiCAD. I usually export ArchiCAD models to VIZ/max and add stuff there.