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obj export with multiple materials

ZBrush Usage Questions
#1

Hi everyone,

Sorry for being frustrated, I hope I am posting this in an ok place. I’ve searched high and low and have spent hours upon hours experimenting and searching for an answer.

A few moments ago I managed to have two different sub-tools have what looked like different materials (by setting them to different colors, but after merging them, they ended up with the same color.

I feel utterly lost. I’ve ordered a handful of zbrush books from Amazon and will dutifully read them when they arrive. I have spent a number of hours doing and watching the basic tutorials.

The export tab (sorry for my bad terminology) says “grp”. I desire to create an object from scratch in zbrush and export the object with multiple materials in various zones (Polygroups?). I’m ok with merging a number of sub-tools into a single object where each sub-tool has its own material.

But no matter what I try, the output mtl file does not list more than one material and the programs that I use to look at the obj file sees only one material.

My preferred workflow (to make use of my knowledge and tools) would be to export a zbrush created obj file and then use Octane and other softwares to manage multiple objects, tweak materials procedurally , and render. But for the life of me I can’t figure out how to get zbrush to export more than one material.

Perhaps I should just not worry about it and simple export a mesh and learn how to use other tools such as blender or 3dcoat to break the mesh into material groups, but the Polygroup concept or sub-tool concept should be able to be made to work in a simple fashion (I would think).

Thanks up front for your time and for pointing me in a direction where I can advance!

simpleton-Piet

#2

I am still struggling with this issue. Perhaps if I ask a very specific type question I will get an answer.

  1. Using Lightbox, I double click to load Earthquake.ZPR
  2. Using ZPlugin subtool master I try a variety of things (merging with different settings) and export to produce an OBJ file.

I can never create an obj file with more than one material. What am I missing. Thanks much for any help!

#3

I believe the simplest solution is just to use multiple objs, one per subtool (don’t merge your subtools together unless they share the same material, otherwise keep them separate). ZBrush doesn’t use materials in the same way as other programs and only allows one texture map per subtool, so all that the exported mtl file does is tell the external program which texture file to automatically load with the obj.

It’s not really relevant if you’re going to set up actual materials in the program of your choice. You’d be better off just importing the OBJs without materials, creating them in your rendering program, and then merging the meshes together if you feel its better than having multiple meshes.

#4

Cryid, Thank you. I was fearful that this was the case. Keeping things together though seems like a necessity (unless the subtool exports maintain a type of relational spacing/coordinates so that they can be easily pieced back together.

In any event, I thank you for letting me know that a direct obj export is not likely going to work well because of the mtl issue and the idea of what makes a material group (I hope I am coming close to saying this right).

The render engine I like best is Octane and if not using a plugin of some type, it enjoys obj files best. Soon (I think) such a plugin will exist for blender. So my current hope is to figure out how to best exchange meshes (hopefully grouped meshes) most effectively between Blender and ZBrush. So my next task on this trail is to see if I can understand GoZ/GoB.

Thanks again for pulling me from a fruitless chase.

#5

unless the subtool exports maintain a type of relational spacing/coordinates so that they can be easily pieced back together

It does, thankfully.

#6

I was messing around and established GoZ/GoB but have not had time to play with it much yet. Thanks for that information about subtool export knowing where it needs to sit in space. For me the simple workflow is usually the best one. So I think that this is probably the best way for me to have some simple/early success. Thanks Cryid!