how to delete inside faces of a mesh

[anupamd]

This one's got me really stumped. I have a shell generated by the voronifracture sop. I'd like to delete the inside faces so I have a nice shell on the outside. I know that the SOP createse inside/outside groups but lets assume that group does not exist, how can I isolate the inside faces and delete them so that I have a nice shell on the outside?

I've tried just about everything.

1. Scattering points then using he ray sop to project the points onto the surface, then attribute transfer to isolate only the outside faces. because the attribute transfer works with sort of a metaball radius the result is very inaccurate.

2. I've tried using the divide sop with remove shared edges. That does not work.

3. I can isolate the top and bottom surface, but I still have an issue with the sides.

4. Perhaps simply doing a fuse, and then deleting coplanar faces will do the trick. But I dont see a way to delete coplanar faces.

[anupamd]

see attached

[Stalkerx777]

Hi. here is a simple solution.

delete_interior.hip

[anupamd]

Thanks for the reply, your solution works but unfortunately it relies on the inside group and outside group actually being intact. I don't have that luxury because the outside group is not correct in my example. See the attached hip. But yea I wish it was that simple

One way is to fuse everything and then delete co-planar polys, but Houdini has no such handy node and Im trying to avoid writing some python, but I might have to.

Hi. here is a simple solution.

delete_interior.hip

cleanvoroni.hip

[edward]

Yeah, this would make a good odforce challenge to do this properly without python. The problem is that SOPs needs some more tools to deal with polygons and such. Doing it in python shouldn't be too hard provided you have fused all your points first. Then the solution in python I think would go something like this:

- for each primitive, build a sorted list of its vertex point numbers

- now do a nested loop which compares each primitive against every other primitve

- if two primitives have identical vertex lists, then mark both of them for deletion

[zarti]

This one's got me really stumped. I have a shell generated by the voronifracture sop. I'd like to delete the inside faces so I have a nice shell on the outside. I know that the SOP createse inside/outside groups but lets assume that group does not exist, how can I isolate the inside faces and delete them so that I have a nice shell on the outside?

I've tried just about everything.

..

this seems to work ( without python ) ..

cleanvoroniz.hipnc