Exporting high poly models

Ottomotto

Any tips on exporting high polly models from zbrush? I always end up getting stuck on this part of my workslow. I just cant export my high poly models for baking. Anything over 20 million points crahes and may or may not successfull export. Ive also run into trouble With exporting an ID map. Polypaint doesnt export with .objs properly, and fbx export crashes at even lower tri counts than obj export. I've also found my fbx export polypaints to be broken too, with black areas on them, probably errors related to files size maybe? Keeping scale consistent is also a hassle, Making sure my decimated retop mesh dosent end up a different scale to the high poly is another thing I've had to look out for

Whats your workflow when it comes to this part of the process?

Kanni3d

You definitely want to decimate your meshes first prior to export. Removing 60-80% of your mesh with decimation master works wonders and doesn't noticeably change any fidelity from your sculpt. 20 mil turns easily into 3mil. Theres a way to store polypaint as vert data i believe with exporting, haven't done it much in a long time, hopefully someone else will help out regarding that

Ottomotto

Kanni3d said:

You definitely want to decimate your meshes first prior to export. Removing 60-80% of your mesh with decimation master works wonders and doesn't noticeably change any fidelity from your sculpt. 20 mil turns easily into 3mil. Theres a way to store polypaint as vert data i believe with exporting, haven't done it much in a long time, hopefully someone else will help out regarding that

Do you even decimate the high poly you use for baking? I export a decimated version to work on in 3dsmax to make the low poly, but I've never thought decimating the baking model was a good idea. Dont you still lose quite a bit of high frequency detail like pores?

Ottomotto

The messed up vertex colours seem to be a max problem so I guess that solved, But I'm still interested in how smarter people go about making ID mapps

Kanni3d

Ahh yeah, in terms of hard surface stuff, you can be pretty aggressive with the amount of decimation. But for organics and high frequency details, you can try decimating at much lower increments, as it is still possible to maintain the high freq details while decimating.

Ghogiel

If it's just a crash at exporting issue, can you split the mesh into a couple parts then export it as multiple objs?

As for polypaint exporting in obj, it does, but iirc objs don't support it officially, so some apps might not read the vert color ZB data from objs. Don't think max's obj importer reads it for example. Worst case is you can make an auto UV in ZB and transfer polypaint to texture. And just pull the texture during the bake instead of the hi polys vertcolor.

I can't tell what you are doing to mess up scale, but you if change the scale in max obj settings or ZB export settings that will definitely do it.   You can just goz, which should avoid mismatched scale issues.

Alex_J

Just repeating others I think, but GoZ will solve your scale issues. And where do you plan to do the baking? Because if vertex color issues is only related to 3dsmax, that might not be an issue.

For instance, if you bake in Toolbag, vertex color riding with the obj should be fine (at least I've baked  vertex color from objs and fbx's IIRC)

Ottomotto

The vertex colour was probably a display error in 3dsmax, they actually showed up fine in toolbag. Regarding Scale issues, I've found that Iporting models in and out of zbrush has messed it up in the past before for me, But I havent encountered that in this project yet, so It may have just been me scalling something or moving it and forgetting?

Regading GoZ, Is there much benefit to that? 3dsmax's exporter seems to struggle just as hard as Zbrush, I havent tried maya but I assume its the same. 

Neox

hehe i never decimate, i use obj, never goz.

goz has failed me too often in the past, lots of the scaling issues seem to come from it

exporting everything in a single fbx creates one gigantic file, which can become a bottleneck quickly, the upside is, fbx natively handles vertexcolors. if you neeeeeed them in max,or maya this would be the way to go. zBrush just slaps the vertexcolors in the end of an obj file, natively obj doesn't support vertexcolors, you need a custom importer to make this happen. 

i didn't bake in max in ages. max by now is only a modelling tool to me.
but max isn't made to display 20+million polies iper object n viewport, but it can handle it in renderer. so an old trick is, to import everything in boundingbox mode, then set those meshes to boundingbox preview. so the viewport doesn't have to render them.

but really, i'd suggest using marmoset toolbag or any other dedicated baker. unless your final output renderer is supposed to be or is synced to 3dsmax. which to me sounds very exotic and unusual by now. 10 years ago, maybe. But nowadays almost everything is MikkT or if the engine is a little older, synced to maya.

srsface

Neox said:

i didn't bake in max in ages. max by now is only a modelling tool to me.
but max isn't made to display 20+million polies iper object n viewport, but it can handle it in renderer. so an old trick is, to import everything in boundingbox mode, then set those meshes to boundingbox preview. so the viewport doesn't have to render them.

but really, i'd suggest using marmoset toolbag or any other dedicated baker. unless your final output renderer is supposed to be or is synced to 3dsmax. which to me sounds very exotic and unusual by now. 10 years ago, maybe. But nowadays almost everything is MikkT or if the engine is a little older, synced to maya.

The bbox mode is a good trick! Though I feel that ever since Max 2018, the viewport has been able to handle tens of millions polies just fine. Manipulating these objects can still be slow depending on the operation, but for just having them in the scene there have been major improvements over the past couple of years.

Also now with the 2021 version apparently Max can finally sync with MikkT. I'm excited to try that out along with the new baker.

kanga

I dunno, but like AIRBORN sed, if you are baking then a dedicated app is the way to go. Like you I dont like baking decimated models if I dont have to. Im using Blender, Substance and zBrush. Character models can be up to 16 mil in zB. Im on a lowly laptop, so if my rig starts to chug I break up the model using DecimationMaster. zB handels a 12 mil model just fine. GoZ to and from Blender is a one to one scale export setting. Exporting from zB for say, Substance is surprisingly an export scale setting in zB of 100.

I do my skin texture coloring in zB, cause it is really a paint app. If you have to bake in a program like substance you can export your hi and lo polys using naming conventions and combine them in substance which will separate the meshes as texture sets. Using fbx means I can get my vertex color in. If you dont have access to a commercial baker then you can use xnormal. Its free and pretty snazzy.

What you really need is a baker that only references your hipolys from disk so you wont have to open them for baking.

So, append a simple cube to your zB ztool, export it as fbx (2016 works fine) and import that fbx into your modelling app. The app you used to make your lowpolys in (this should already be synced to Goz as far as scale and position go). Just keep exporting the fbx from zB until you find the magic number and everything lines up perfectly. Use the correct export setting to pump out your separate fbxs and bake.