Hacker News Reader

Comment by Daub | Hacker News Reader

As someone who teaches 3D, a 'high quality' model would need to have clean topology: all quads which flow around the form in a predictable and rational manner. From this, I would expect a clean texture map. I am fairly certain that current technology is not up to this.

I have seen a few of these papers, and (from my limited experience) very rarely is the 3d model avauable for review.

View on HN

https://github.com/wjakob/instant-meshes

I ran Instant Meshes over a model of Mount Chimborazo and it did an okay job. Although the mesh was fairly uniform with its quads, the topology looked weird. Like the typographic equivalent of "rivers" running through the mesh. I decided to keep the imperfect topology, with some amount of decimation, because it looks better.

https://i.ibb.co/2nX8WfC/chimborazo.png

Retopology tools are discussed on a Blender forum:

https://blenderartists.org/t/best-auto-retopology-tool-ever/...

Have you tried them? What are your thoughts? What tool would you consider state-of-the-art?

Instant Meshes is pretty good. We have it installed in all our labs. The results you share seem fine for the purpose. In our experience, Quad Remesher is the best. It certainly helps that QR sits inside of Blender as an add on (unlike Instant Meshes). It is also pretty much industry standard, being used in Max, Maya, ZBrush. As for its results... I find that it has a deeper 'awareness' of the source topology. The meshes are dense when they need to be and not dense when they don't need to be.

A good test of any re-mesher is to apply it to some 3D text. 3D text geometry is famously horrible. Another test is to apply it to a face. Face topology is very prescribed: there is a (mostly) single way of doing it. Any non-standard approach will create issues, especially if you wish to animate it. I would not have expected any automatic approach to work very well, yet have been surprised by the quality of QR.

For human topology wouldn't you just transfer it with keypoints to a standard topology using something advanced like R3DS Wrap? That's what is used in human scan data conversion for film to get a realistic animatable double for VFX shots.

I'm ashamed to say that I have not heard of R3DS Wrap. It does not seem to re-mesh as such. Rather it seems to 'wrap' an existing mesh around your raw mesh. It also manages the baking, which is sweet.

This seems like a valid approach. After all, every human figure in a Pixar movie has been sourced from the same base mesh.

Right. Outside of creating something to show off in a web browse, this is currently at best a quick way to generate disposable background assets for VFX. Definitely not usable for AM or 3D printing, and more work to clean up and stylize for any given animation.

Once we get artists to start producing LoRA on UV wraps of their own assets, I think it'll get interesting.

No, but it's not exactly hard to retopo bad geometry.

You can download the models from Hugging Face.

In my experience depending on the model, it can be between hard and very hard. Blenders remesh will produce something reasonable but with a gazillion polygons. Guided approaches are a lot better but are labour intensive as the user is effectively tracing over the source model.

Retopology will destroy the old uv map, so a new map will need to be made. Following that, the old textures will need to be baked onto this map.

I have spent easily as much as a day cleaning up (I.e. re-mqking) 3d scans.

> Guided approaches are a lot better

Yes, they are.

>No, but it's not exactly hard to retopo bad geometry.

Said no actual, working 3D artist ever.

I guess we'll just have to agree to disagree.

Are you a working 3D artist? If so, would you mind linking your ArtStation profile?

Otherwise, we don't have to agree to disagree.

You can go and ask actual working 3D artists how they feel about retopologizing bad geometry, and find out what the reality of the situation is.

We can "agree to disagree" with each other, but let's agree to agree with reality.

Will this suffice?

https://www.imdb.com/name/nm1381344/

Absolutely, thanks for sharing that and your opinion - adjusting my views accordingly (we don't have to disagree - I was wrong).

Have you found 3D Gen AI useful for your work yet (with all the quality issues that it has so far)?

Thank you. I appreciate your ability to reverse course.

The quality of 3D AI isn't there yet, but it's just a matter of time. When Sora quality 3D generation arrives, it will be incredibly disruptive.

Reply on news.ycombinator.com