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Using Multi-Region UVs in Modo 501

Introduction

Many programs like Maya and 3ds Max allow you to spread your UVs out beyond the normal 0-1 UV space so that you can achieve as much pixel density per UV shell as you want. Texture painting apps like Mudbox and Mari also provide for this and when they output the textures, they save them with file names that correspond to the UV region the texture is assigned to. Maya and others recognize the naming convention and assign the texture to the right UV space, but Modo requires that you tell it which UV space the texture goes to. This tutorial will show you how this is done.

NOTE: This tutorial is not meant to explain the root concept of UV regions, how to use UV regions in ZBrush, nor how to assign textures to materials in Modo. This only shows how to assign your previously made textures to the right regions in Modo.

Downloads

Tutorial files and hi-res images

Software Used

 

  • ZBrush 4.0
  • Modo 501 (This works in 401 too, but I haven’t tested it in versions previous to 401.)

 

 

Part 1. The Situation

Here in fig. 1, you can see that I’ve made a quick (and ugly) sculpt on a plane in ZBrush. I then exported that to Headus UV Layout and set up the UVs onto multiple regions. Finally, I brought it back to ZBrush, split it into polygroups by UV region, and took a displacement map for each region. The shells have been deliberately rotated to emphasize that they can be positioned any which way within their respective regions.

zbrush_setup_webres

fig. 1

In fig. 2, you can see the final render from Modo. Clearly, there are no holes or weird things going on.

zbrush_setup_webres

fig. 2

 

Part 2. Reassembly in Modo

Here’s how it’s done.

  • 1. Once you bring your geometry and textures into Modo, you’ll apply them all atop the material in the Shader Tree, as seen here in fig. 3.
  • 2. Next, you need to visit each image and set its channels so that Modo knows which UV region it belongs to.
  • The channels to set are:

 

  • Horizontal Repeat
  • Vertical Repeat
  • Offset U
  • Offset V

 
imagechannelsettings_webres

fig. 3

 

Part 3. Figuring Out the Right Channel Settings

This part can be a little confusing. In brief, you can see that if you follow the chart below, a pattern emerges. U is the horizontal values, V is the vertical. My chart here only goes to the fourth region but you could expand this as needed for as far in either direction as you need to go.
When Mari and Mudbox output their textures, they take advantage of the unique positions of these regions and label them based on that information. For example, Mari may name a texture ‘color_2312′, meaning that that texture corresponds to the region at U 2-3, V 1-2.

Mark Rossi wrote a script based on this concept that automatically sets up your image channels based on their file names, where the files are named according to their regions. The script works for both Mari and Mudbox, which each have different naming conventions but do the same thing.

uvregions_webres

fig. 4

 

Conclusion

Modo doesn’t make this an easy process. But as you can see, the use of multiple regions is perfectly possible and seamless in Modo. Please post any questions as .

 

Credits

Special thanks to Mark Rossi and Tim Crowson for all their research and hard work on this topic. Their threads on this subject at Luxology, are how I came to understand it. You can read those threads here: