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Booleanl a very compex Model - Workflow


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Good evening :)

I am trying, to boolean a very complex model inside houdini.

Its an engine that has thousands of little parts. Since the original format is not supported, I had to use Softimage first and than export the geometry.

The first problem of course is alot of open caps, dissconnected edges etc. Actually most of models we get from architecture/ingeneur applications, give us alot of headache :)

Anyway, I thought first thing to use would be a 'remesh'.
Takes some time, but thats working. Problem is, the geometry will be smoothed out and so on.
And when using 'cookie' houdini is crashing.

What about using VDB?
I tried that. Super fast and actually a nice result.

But when I combine the engine with a cube to cut out a cross-section and 'convert to vdb' to get a polygon model, the model has alot of holes, disconnects etc.

Is there a recommended workflow?

I exported the model from Softimage as Alembic btw.

Thanks alot,


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hello Skybar,

Yea, thats an option to wait, but till than I would like to test if I can handle it with other ways.
I just found out that I had to change the Iterations in  'VDB Convert'. I now have quite a nice Model.

Anyway, looking forward for more techniques :)


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Here is @eetu's render-time booleans. Didn't try it myself yet. If you have proper watertight solid in STEP, you may try to export it as FBX from Rhino (and if it is Solidworks model, it can be exported to STEP from there). It should output good geometry with no holes, it also can be divided at export time, like with Bricker in Divide SOP, but with perfect normals computed from NURBS surface. In that case you won't get any long and narrow polygons which shade badly in Mantra. Good geometry can be clipped and poly-capped quite well, even H15.5's Cookie may work.

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Softimage has one of the worst NURBS implementations available, so I'm not sure if you don't shoot yourself in the foot there.

If all you want to do is convert all kinds of NURBS/CAD data, I can highly recommend MoI ("Moment of Inspiration"). It's coded by the original developer of Rhino, but much easier to use, artist and Wacom friendly, much cheaper and exports very very good meshes. It imports 3DM (Rhino Format), IGES, STEP, SAT and DXF, I would recommend STEP if you can get it, then SAT and if nothing else is available, IGES.
Export could be OBJ or FBX (there also is LWO but Houdinis LWO converters are broken), DXF, Sketchup and STL.

I have Rhino too, but often prefer MoI for conversion.

http://moi3d.com/    Don't mind the toy-like website and the simple-looking GUI, the dev actually wants to stay a bit under the radar and "simple" in this case does not mean primitive, but easy to use... ;-)

For the booleans I also would wait until tomorrow...  (Or do it in MoI if it doesn't need to be animated... NURBS are RAD for Booleans).



Edited by Thomas Helzle
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thx @MENOZ , @f1480187 and @Thomas Helzle,

will check you input right not.

Actually, its a very "bad" format, *.*jt. from siemens and the only applications that can handle the modles are some CAD programms and 3Ds Max and some other special programm.
I dont own both of them, so I had to use custom script in Softimage to read it. Its working, but with alot of problems.

Like Thomas mentioned, the "mesh" I get in Softimage is ugly bad.
Thats why I thought, I could maybe use VDB to get a clean result.

One good thing is, I can group the mesh and "only" have to work on a part of the hole engine.
Its still a lot of fixing, but that could work.

Got a nice result today on fixing smaller parts, creating cross-sections and putting them together with the original mesh. I again used VDB workflow to create a clean and fast model to replace the original, messed one.

Tomorrow I can show some of the progress to make the problem more visible. Not sure, what I may shwo right now.

Thx again for you input, will check that out now! :)


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