Generating UV's without losing polypaint?

[JColling]

Hello -

My usual software package is Maya. I don’t do anything outside of Maya unless I absolutely have too. zBrush provides great sculpting capabilities, so I use it after “fleshing out” my model in Maya. Now to my issue(s) with zBrush…

WHAT I DID -

I created a model in zBrush. It has 1.1 mil polys. I have applied polypaint to the model. The model does NOT have UV’s on it. It is just an essentially finished model with polypaint, which now I find out NEEDS to have UV’s and thus the polypaint needs to be a texture map. I wish I would of knew this before hand…So now I need help. Please keep reading.

WHAT I NEED TO DO -

I need the model to have UV’s on it. How can I do this without losing all my polypaint data? Also, when I decimate the model, my polypaint data disappears…I need to KEEP the polypaint data. The only real thing I am trying to achieve here is to have the model exactly as it is now, just with UV’s on it.

So, I need to do the following…

• Decimate the model
• Generate UV’s for my model
• Convert the polypaint data to a texture map that I can export and re-apply (if needed) in a 3rd party 3d software (in my case, Maya).

======================================================

I know what I am trying to do involves some steps to it, so anyone who is willing to have a bit of patience with me and help me through this, I would be in your debt. From one artist to another, thanks to anyone for any help with this.

Any questions, please ask me. I can’t show the model per the agreement I signed (confidentiality clause). Thanks again for any help with this.

-J

[Bangers]

In UV Master, click ‘Work on Clone’, this clones your subtool and sets it to the lowest SubDiv level. Work on your UV’s as needed, then when satisfied just click the ‘copy UV’s’ button and select your original Subtool, then click Paste UV’s.

Now your Models has UV’s, you can go to Texture Tab, and select, ‘New Texture from PolyPaint’, make sure RGB button is on.
Might be good to set a UV size in the UV tab above. For 1.1 million subtool , 2048 should be ok, but if not enough resolution, increase to 4096.

[JColling]

Thanks for the help. I tried what you said, however, it did not work. So, I tried it on a sphere and still no luck. Here is what I did…

I created a sphere on the screen. Entered edit mode. Clicked on create polymesh button. I then filled the sphere using fill object to make it white. Then I clicked clone to clone it. It cloned out no prob - I then drew a red line on the sphere. I clicked copy UVs. I switched back to the original sphere and clicked paste uv’s and the history seems to update, however there is no visual change to the model. I then used create new from polypaint. and made sure RGB and the texture itself was on. Still no luck. The red line I drew does not get pasted on (it seems). It remains white…

Did I do something wrong? Please advise. Thanks again for helping me out!

[dillster]

Painting the red line on the cloned sphere won’t see it transfer to the original sphere when you paste UV’s. Paste UV’s to the original subtool only transfers the UV’s from the clone, painting should be done on the original instead.

[JColling]

@ dillster

Worked! Thanks a lot. I really appreciate the help - Now I can sleep.

Just a quick followup question for anyone who knows…I noticed - if a mesh has around a million polys, the unwrap process never completes. Clicking the UNWRAP button just causes zBrush to hang, although it looks like its working… Is there an article or something that talks about the workflow for creating UV’s on a very dense mesh? I don’t like to have to wait 3 hours for an UNWRAP to complete and even then it still is in the same place it was when I first clicked the UNWRAP button…Any insight into this is appreciated.

Thanks again!

[Doug_Jones]

Many methods can be used to model. UV’s are created at a lower subdivision level. …That’s why they are important.

[Bangers]

JColling, Here’s a few steps for a UV workflow.

If your model has multi million polys, then duplicate it and use Zremesher. Once remeshed, enable RGB, and click on the paint brush icon to the right of your subtool. Now subdivide your new mesh a few times. Go down to Project, in your Subtool Tab, and press Project All, to reproject all high res paint info and details to your new mesh.

(tip, if your new mesh has many white dots after you reproject. Fill your new mesh with a colour average to your original models paint, to use as a base. Then reproject again, it will get rid of the white dots)

Using this new mesh with subdivisions >

Go to UV Master, click ‘Work on clone’, click Unwrap button.
While in UV Master, you can modify your UV’s, click the Flatten button, your mesh will be spread out into a 2d island, if you have Polygrouops button enabled, it will be seperated into multiple islands.
Here you can move around and re-arrange you mesh to your liking, using the Move, Rotate, Scale buttons. You can also use the Move Brush and Shift Smoothing. This is to better organise your UV’s, just keep your island(s) withing the bounding box.

One thing, while in this flattened mode, don’t press Ctrl + Z (Undo), Zbrush doesn’t like this.

When finished editing your UV’s, click ‘Unflatten’ button, and click Copy UV’s, switch to your original mesh (with subdivisions), and click Paste UV’s

To check if your UV’s are applied, go to Texture Map tab and apply the ‘Texture 19’ (UV Check) from the list of default textures.

As before, in the above UV Map tab, select your map size, 2048, or 4096.

You can then turn off the texture (UV Check) and click in Texture Map > Create > New from PolyPaint.
Now you’ll have your Polypaint converted into a texture to use in Photoshop or for use in another 3d app.

I didn’t go into UV guides, and Control painting, there are vids which explain this on youtube, you should check them out, just search for UV master.

Tip: Save your work before you go into UV Master - So if you happen botch something up, can easily reload and give it another bash :]

Hope this helps ~ Cheers