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Confused about uv's

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I am trying to retopo a sculpt which is made of several individual parts, into several retopo objects, and export everything using the same UV set. The individual parts are important as they get animated in my game engine later.

It's kind of working for me, but I am not really sure what I'm doing, and there's certainly some things I can improve upon... Here's what I'm doing:


I sculpt the objects first. This is fine. I have them set up one object per layer.

Next I go to retopo room, and create one layer for each object, with the same sames.

I hide everything, then show one sculpt object, and the matching retopo object, and I do the retopo. I would like to do different sized baking cages for the objects, so I now bake this object.

I proceed to hide these, and repeat for the next object, baking again with a new cage.

Question 1: my understanding of baking is that it creates 2d textures with the high poly info, but since I haven't done a UV mapping yet, what's going on? Is the bake info stored in an invisible 2d texture somewhere?

When I have baked the objects, I add seams, and Unwrap and Pack. I also do Unify UVs.

When I switch to the UV room, I can see there are still multiple UV sets.. WHat is the point of these when I just dealt with UVs?

Question 2: What and why exactly did I just unwrap and pack in Retopo room, since the paint room/uv room seem to have their own independent UVs?

In the UV room I now do Unify, delete the unused UVs, unwrap, and pack.

Now I go to the Paint room. I use the Fill tool and click each object to paint them a different color (material ID for substance).  I hide the normal map, and merge visible, to produce the material ID map, which I then export, then re-enable the normal map and export that.

Question 3: Why is there a Surface Material per object, but named "Default", "Default1", "Default2"... ie, after the unused and deleted UV sets? Wouldn't it make sense to use the retopo names? Are these multiple surface materials due to me baking multiple times? 

Question 4: Can someone please explain the architecture of what's happening here? It looks like there are 3 entirely separated groups of UV sets, one group for the bake, one for the retopo room, and one for the paint room. Why? What is the intended workflow here? Am I missing something obvious?


This whole thing seems very clicky-clicky and repeative, with multiple versions of things which is not well explained, so I'd welcome some suggestions on which steps I might be able to eliminate or avoid!



Edited by Innovine

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I don't think that you can bake without UVs. If you don`t do UVs manually ( in "Retopo Room" ) BEFORE baking then 3D-Coat does the automapping.
These things all happen in the "Retopo-Room" - retopo object(s) with retopo tools, UV-stuff (e.g. add seams, unwrap, pack  ...) with UV-tools and then "finally" the baking (again if you didn't do it maually - in the "Retopo" room -then 3D-Coat does the UV-ing and packing  before the baking process for you automagically.
Then you have "Paint Room object(s)" whose UV-stuff (Surface Materials) could be altered in the "UV-Room" (e.g. Unify UV,  .... ) if need be.


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Currently I have UVs in the Retopo room, and these look good, however if I go to the UV room, and unwrap, they are chopped up differently. Why is this? My model is symmetric, and I've copy-pasted the UVs on top of each other in the retopo room, but when I go to the UV room, the unwrap gives me asymetrical islands... 

Again, what is the point and usage of the UV done in the Retopo room as an independent thing from the UV done in the UV room? I do not understand why the retopo object is different from the paint object, and why the retopo UV is different from the paint UV.

Edited by Innovine

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This old Manual at page 108 have information about it. 

On 12/28/2012 at 1:46 PM, Psmith said:

Each time you create new topology, (automatically), you create a new Retopo Group - and each time you merge this topology into the Paint Room, you create new "Objects" in the Tweak Room - as well as new texture painting layers.

Unless you use the "eye" icon and hide these various groups and layers, you will see them overlapping.

Even if you have created a new, manual Retopo Group - the UV Room will not display this new, unwrapped Group unless you first Bake the Retopo Group into the Paint Room (Bake Menu/Bake . . . . ).

If things get too confusing and you want to start from scratch, just delete all of the Paint Room layers, the Tweak Room "Objects" and your unwanted Retopo Groups - and try again.

Turning off Voxels while in the Paint Room is, indeed, necessary - unless you are painting vertex colors - otherwise you will see the Voxel object interfering with your Retopo mesh (which is the one you wish to texture).

Greg Smith

Hope it help

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