Low poly to voxel

[dvijay]

Hi,

I'm pretty new to 3D Coat so please bear with me for possibly trivial questions.

I'm trying to load a low poly human mesh and convert it to a voxel-based model so I can sculpt additional details/accessories (for example hair). I'm not able to do this very successfully. Here are a few things I tried and some questions I have.

The model I'm loading is about 20k triangles. When I first open it in 3D Coat (voxel mode), the Merge tool show the estimated poly count as 414. I'm not sure why that is. I can hardly see the model, probably due to the import scale factor but if I scale the model the poly count goes up.

If I don't do any scaling and simply say Apply, I don't see the model at all. If I scale the model sufficiently large (1M poly) and then Apply, the model is converted but with a whole lot of holes. I also tried subdividing the model and I can see the model getting smoother with each subdivision. Even after 4 or 5 subdivisions (each iteration takes increasingly longer and longer), when I Apply, there are still too many holes in the model.

I tried a lot of variations on the above (scale, subdivide, etc). There was one time I actually managed to do Apply and have the model fully convert into voxels. Clearly I cannot retrace how I got it to convert. I was not able to do it again.

I did not think what I'm trying to do here is that complicated. I must be clearly missing something. Are there any specific steps or settings I need to use for this?

Any help is greatly appreciated.

[philnolan3d]

When you pick a mesh to merge you see a model load in that is really a mold that will be filled with voxels. Voxels are all the same size so if you make the mold bigger you can fit more inside (thus higher resolution). After you hit Enter the "mold" model is discarded. and the model you're actually working on is something entirely new. Remember that with voxels you're not moving the points or polygons around, you're simply turning the invisible voxels on or off, the one's that are "on" are surrounded by a triangle mesh in real time as you work. You can see that by holding W for the wire frame.

What I normally do is pick my model to merge, then hit the Auto-scale button. I find it usually needs a little more scale than that but you can try that. Then hit Enter and pick a different tool so I can see the mesh clearly. If there's enough detail, fine, if not I hit Undo and scale it up a little more, the hit Enter again.

If you'd like to keep the original mesh you can load it into the Retopo room before you start sculpting in the Voxel room, then occasionally pop back over there and hit the Snap button in the tools if you made any major changes to the voxel mesh.

BTW I think this all generally tends to work better if you start with a quads model, instead of triangles.

Hope that helps, have fun playing.

[Psmith]

Phil:

Thanks for this very nice explanation. It answers a lot of questions coming from different perspectives. It's an overlooked topic, for sure.

Greg Smith

[philnolan3d]

No prob, I've actually given almost exactly the same explanation elsewhere.

[dvijay]

It is indeed great explanation. Thanks for clarifying some things for me.

As to my model, I'm still not having much luck. No matter how much I scale my mesh (I tried from 50K all the way up to 10M!!) once I apply, all I see is an outline with plenty of "holes" in it. I may be doing something wrong. I can try to attach a screen shot if necessary but its probably very obvious. Like I mentioned earlier, I did manage to convert is successfully once (at around 1.5M polygons) but I can never do it again

[philnolan3d]

A screenshot may be helpful. Maybe a dumb question but are you picking another tool after hitting Enter? If you just leave the "proxy" mesh there it looks pretty nasty since you have two meshes occupying the same space (co-planar polys). The other thing to mention if I didn't above is to make sure the mesh you import is closed and water tight (like if you filled it with water none would leak out) You can either do this in another program or in some cases the "Make Holes Closed" button in 3DC is good enough. Even if you think it's is water tight maybe there a hole you just can't see, so you could try hitting Make Holes Closed.

[dvijay]

Thanks for helping me with this Phil! I'm attaching an image stitched with a series of screen shots. Hopefully that can indicate where I might be going wrong.

And I forgot to add. Yes, I am making the mesh closed, I am selecting a different tool after hitting Enter/Apply.

[Tony Nemo]

Are the normals facing the right way in the original?

[philnolan3d]

Well it would help to see it if you picked another shader so it's not just solid black. But yeah that is a tricky one. Tony's question is a good one, make sure the normals are all facing the right way.