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Tuesday, July 23, 2013

Ptex displacement and texturing in Mudbox to V-ray for Maya PART 1

First create your basemesh in Maya or your tool of choice. Ptex is not a silver bullet so here are some things to remember when creating your base mesh.
  • Be very careful how high you take your ptex texel resolution. You can basically bring your computer to it's knees.
  • Ptex will work best with EVENLY SPACED Topology. Otherwise parts of your model will be high res and other parts will be pixelated.
  • Try to use quads whenever possible, tris and n-gons may introduce problems.
  • Clean your model up. Polygons menu set>Mesh>cleanup in maya. Try not to have any errors when you import into Mudbox.
  • Correct SCALE. Export your OBJ base mesh from Maya at the same scale as a default Mudbox model. DO NOT scale your mesh up or down. Export it from Maya at the correct size initially.

Keeping these in mind. Let's continue!

1. Export your mesh as an OBJ from Maya or your tool of choice. Here is my mesh. It's more detailed then it needs to be but it will serve to show this process just fine.

2. Goto file>import and select your OBJ. Mine only gives an “incomplete UV set” message” because I didn't create any UV”s for the model. This isn't a problem continue on.

3.Select your mesh in mudbox. Then go to UV & Maps>PTEX Setup. Your model will get covered with diamonds showing the resolution of the ptex. 

4. Increase or decrease the resolution until the diamonds are sharp at the distance you will be seeing it in the final render. In my case i'm going with 16m texels (roughly 4k texture resolution. Press “done”.

  • Ptex Tips

If you want to increase the resolution of just a part of your Ptex file (like add a larger Ptex
to just the forehead of a face)... Go to Windows -> Preferences -> Render -> Render Selected By Face.

If you ever need to upres or downres your Ptex painting later, just go back into UV & Maps>PTEX
Setup, it will remember your current setting, and let you modify the resolution. Remember, the
more resolution, the larger your Ptex file and the more RAM it takes up.

5. Now that we have ptex setup let's start sculpting. Press shift  'D' to increase the desired subdivision level from zero. I'm taking mine to up to level 5.

6. Sculpt and paint your model. Lots of tutorials about that process online so I won't go into that at all. Once complete move on to the next step.

7. Go to UV's & Maps> Extract texture maps> New Operation' from the menu bar.

8. In the pop up select to export a 'Displacement Map'.
9.In the Target Models box: select your mesh at the lowest desired subdivision level for your basemesh - usually level 0. but sometimes level1 if you need a little more detail in the base mesh.

10. Set 'Smooth Target Models' to CHECKED.
11. Set 'Smooth Target UVs' to UNCHECKED.
12. Set 'Use Creases & Hard Edges' to CHECKED.

13. In the Source Models box: select your mesh at the highest subdivision level in my case level 5

14. Set 'Smooth Source Models' to CHECKED.
15. Set Method to 'Subdivision'
16. Change the Texel Distribution dropdown to 'use PTEX Setup' if you don't your displaceament will be small and pixelated.

17. Click the 'Base Filename' options box (...), choose a filename and directory to save your Ptex file too preferably with DISPLACE in the title.
18. Make sure Data format says '32 bit float'

Here is a pic of all settings.

19. Click the 'Extract' button to run the displacement map generation.
Your displacement map is now ready for use!

20. Select the layer your painted in the layers palette in Mudbox (see pic) Right click on the layer and select 'export selected'

21. Choose a name and location for your file. You can also choose Ptex 16 bit to keep the file size down if you wish. Save the file as DIFFUSE.

Press 'page down” key on the keyboard until you reach subdivision level 0

Select your mesh in mudbox and go to file>export selection. Choose a location to save your low resolution OBJ.

Now we should be done in Mudbox it's time to move to Maya and get it the displacement working! It's time to move on to PART 2. Stay tuned for that in the next couple of days!!