Zbrush to 3dsmax and Mental ray render

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  12 December 2012
Zbrush to 3dsmax and Mental ray render

Hi,
I'm trying to integrate zbrush meshes into 3dsmax and keep the same amount of detail as in Zbrush (I need to have it unwrap with a texture). I tryed many things:

- low res with normal maps (not crisp enough);
- mid res with normal maps (not crisp enough);
- low res with displacement map;
- mid res with displacement map;
- Decimation master (doesn't work so well with the stone wall.. I get to see the triangles even with a 200k mesh).

I render in Max2012 with Mental Ray. So far, the best results I got were from Arch and Design Material was with Mental Ray connection and the 3D displacement shader. The only problem is that the scaling of my mesh changes a alot when I apply this displacement. Then, when I want to render my occlusion pass with the override texture... it doesn't fit anymore. Whats the best way to integrate zbrush stuff (for instance.. a 10M poly sculpted stone wall) in Max? Is it normal that I get so much scaling differences (few centimeters).

Thanks!
 
  12 December 2012
I've had really good luck using uv master in zbursh to get the uvs, then useing goz to bring the low res mesh into max. Instead of using normal or dispalcment maps Ive been useing vector displacment maps.
http://www.pixologic.com/zbrush/features/GoZBrush/
http://www.pixologic.com/docs/index...splacement_Maps
 
  12 December 2012
I'm gonna try this for sure. Thanks for the tip!
 
  12 December 2012
Just come back if you have any questions. I know I spent quite a few days sorting it all out.
 
  12 December 2012
Hey there,

So, I made a few tests yesterday. I read the 3dsmax help file and the links you gave me. It didnt work 100%. I got few questions for you (I'm working with max 2012 and zbrush 4r3):

- In the zbrush pref, do you put the FlipAndSwitch to 7?
- In the vector displacement map roll out in zbrush, do you click the 4 buttons?
- In max with mental ray.. do you use standard mat or arch and design? I guess you add the vector displacement shader?
- What value you put in the object properties. I think you need to uncheck the ''Use Gloabal Sub Settings''?

Thanks!
 
  12 December 2012
As soon as I can get to my machine I will post my settings for you.
 
  12 December 2012
Here's my settings.
FlipAndSwitch 7
Tangent FlipAndSwitch 11
Tangent Eval Mode 1

In the vector displacement settings.
tangent checked
32 bit checked of course
snormals checked
smooth uvs unchecked.

Bringing the map in to max. Don't use color correction when importing. Set the blur of the map to .01. Oh and you'll probably need to flip it in the vertical in Photoshop Zbrush seems to export wrong whether I tell it to flip it or not. Then set the displacement to 100 or 1 depending on what material your using.

As for the mental ray properties I still use the global settings. In the render dialog box I change the Max Subdivisions to 64K.

I generally have pretty good results with this. If your still having issues let me know. I know I've had to mix these settings up a few times to get the right results.
 
  12 December 2012
I forgot to mention that gamma correction can obviously mess with the map a bit as well. I tell max to use the images own gamma.
 
  12 December 2012
I'll try that as soon as I get a chance! I'll post an update later this week-end,

Thanks again!
 
  12 December 2012
I have found ZBrush vector displacement to be ineffective in Max with mental ray.

I admit that the results are more accurate than traditional height maps but they still don't live up to the concept of the vector.

For example we are meant to be able to achieve "undercuts" (like the mushroom cap from a plane effect) because any given vertex can displace in any direction but in my testing this just doesn't happen at render time.

When the ZB version with VDM support was released, and after hours of testing I eventually gave up, hoping that Pixo and/or Autodesk would eventually sort out the technical problems.


I don't discredit either developers for what seems to be a compatibility issue as it's still an emerging technology but it's far from perfect. I have gathered that it's something to do with the way a surface is sub-divided differently between apps.

It's possible that the VDM shader in Max is more designed for use with Mudbox generated maps.

Anyway, when I get a chance I will have another go with your settings, viro.

Also, wysiwyg25 - I noticed that you mentioned in your example a stone wall. In the case where you are not deforming the mesh with animation you do not need a tangent map, in fact you will get a more accurate effect using a world map.

Sorry if I went off on a tangent (no pun intended), just wanted to contribute. Thanks guys.

 
  12 December 2012
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