ZBRUSH 4R8 Unwrapping issue

[Serane155]

Hey everyone,

I’m having an issue with unwrapping a model I made in 3Ds max. I’ll try and make this a summary (hopefully it conveys my problem).

Basically i wanted to put an alpha on the walls of the building i’m working on. I have managed after many attempts to make it in a low-poly way
(Approximately 298714, which i assume is quite a good number for low-poly), I can’t re-mesh it because it would destroy parts of my building, it is important to
mention that i inflated my alphas in an inverted mask in the axis you see (can’t remember which one it is)

Then i went back to 3Ds max to unwrap my model because that’s where i built up my scenes in PBR, ready for render, (with vray for those wondering)
I cannot do much with such amount of polys so i can barely move my model (i work on a laptop, with AMD radeon graphics and i5 core 7th generation, Lenovo yoga computer)

I tried unwrapping it in 3Ds max but it freezes because there’s too many polys for Max i believe.

Tried making a UV map (in ZBRUSH), with 1024 res’ and tried unwrapping it with UV MASTER, the freaking software says my poly-count is too important.

I’ll repeat again I CANNOT GO DOWN otherwise i loose my details on my alphas which i do not want to loose.

I’m trying to unwrap this model because i need to paint it on Substance painter, i already tried Shells, dynamesh and subdivs or booleans, the only thing i haven’t tried is the move topology because i’m not familiar with it

Please help i’m out of options…

Thank you!

[Cryrid]

There’s not much you can do: 298714 polygons is a lot of points for a low-poly model, and if its too much for your system to work with than it’s too much for your system.

You could try using Decimation Master to get it under 50-60k. Yes this will mean losing geometry, but it will still do its best to maintain all that surface detail to the point where a human eye probably won’t even notice the difference.

Otherwise, you’d be better suited to taking different workflows in the future. Three points come to my mind in particular:

1. This Tool looks like it’s been dynameshed to provide the geometry for detail, instead of relying on subdivision. Subdivision would leave you with a much lower base level that you can UV.
2. Generally when you UV a model and bake or create maps in a program like Substance Painter, the whole goal is to use that texture to contain all those micro surface details rather than the geometry itself. A shape like this can easily be manually retopologized into a true low-poly version (probably under 400 polygons, just focus on the silhouette only). You can then UV this simplified version, then bake the detail from the sculpt to this new one (the sculpt won’t need UVs, it only needs to occupy the same space).
3. Alternatively you could just use the simplified model and paint the surface details (small bumps) in using Substance Painter, skipping the sculpt/highpoly stage sculpt entirely (the lowpoly would benefit from some bevels in this case, but would still likely be under 2000 polygons). These days a sculpt only needs the create the larger and medium details, while Substance can non-destructively provide the micro ones.

[Spyndel]

Hi there! A few things to clear up here.

1. Upgrade to the most up to date version of Zbrush . It’s free for registered users. I mention this because I just answered this same issue with another user, and they claimed that simply upgrading improved the performance of UV Master to be adequate for their needs.

2. Cryrid is correct though. Your mesh is simply too dense to expect the best results from UV unwrapping. The good news is you absolutely CAN reduce your polycount, and create normal and displacement maps to display that high poly detail in programs that dont perform well with extreme poly counts.

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If you’ll forgive me for copy and pasting, Ill place the steps here again for convenience:

When you’ve got a fairly high resolution mesh with no subdivision levels, what you’d really want to do is create a more traditional version of your tool with a low poly base, and multiple levels of subdivision all the way up to your original. Some operations work better on or only work at low poly, and most other programs wont cope well with high poly meshes of the sort Zbrush can create. In the case of UV unwrapping, it’s a CPU intensive operation, so the more polygons to process the slower it will be, not to mention UV unwrapping is easier to control at low poly when you can still make sense of the individual polygons. So you create texture/displacement/normal maps based of the highest level of subdivision, and map those to the lowest level of the mesh for portability.

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The first thing you need to do is create a lower poly version of your model, and give it multiple subdivision levels. What you’re aiming for here is to have Zremesher (or other) accurately capture the basic shape with nice evenly distributed topology. Dont worry about fine detail.

1. Duplicate your source subtool so the original is preserved. ZRemesh (or otherwise retopologize) the duplicate to have a lower polycount with well distributed polygons. You will lose detail doing this, but you’ll get it back.

2. Subdivide your duplicate mesh (Tool > Geometry> Divide) up to a density sufficient to hold the surface detail, as well as any polypaint, from the original. Follow the instructions on this page, and project the detail (color and sculpting) onto the newly subdivided model. You should now have a version of your model with all the detail intact, except now with multiple subdivision levels and a low poly base.

3. From here, you can create UVs for your mesh. Switch to the lowest SubD level and follow the directions on creating UVs, either with UV Master, or one of ZB’s quick tile mapping options, or with any other tool you prefer.

Good Luck!

[Martin77]

Hi everyone, this is my first time posting here and I’m a Zbrush novice. I just recently learned the basics and I have a small issue. I created a model with the uvs set up exactly how I wanted, I then imported this mesh into zbrush. I sculpted the model until I got it exactly how I wanted it, however I foolishly believed that zbrush would compensate the uvs to accommodate the differences created after sculpting…I was wrong. In the link attached I’ve provided an image showing my exact problem, stretchy UVs. I would usually just fix this in 3dsmax however I need to use the model on its 4th subdivision level, and sorting out the uvs is proving to be too much for my PC to handle. Is there any way I can fix this? I’ve tried relaxing the uvs, it doesn’t work because the seams have disappeared apparently. https://scrabblewordfinder.vip/ https://www.applock.ooo/

[Spyndel]

@Martin77

When working with a mesh with existing UVs that must retain its topology exactly, you need to first store a morph target at the lowest SubD level. You can then switch back to this original mesh for the generation of texture/normal/displacement maps.

You may be able to salvage your sculpting work if you still have the original mesh you imported. Store a morph target for the original (or a duplicate, ideally), subdivide it sufficiently to hold the high res sculpted detail, then append the previous sculpted version as a subtool. Project the detail from the sculpted tool onto the original tool with a morph target, then generate your maps from that.