ZBrushCentral

UV Maps & Second Life Sculpted Prims

ZBrush Usage Questions
#1

I just recently downloaded the trial version of ZBrush 3.1, and I’ve been trying (with varied success) to learn how to use it. Although it’s a far cry from its true purpose, I really only aim to use ZBrush to create so-called “sculpted prims” in Second Life, which is just one way of saying that I want to use ZBrush to create objects with a very specific topology and a very low polygon count so I can use them in Second Life.

A tiny bit of background: for reasons beyond my control, in order to make a sculpted prim for Second Life, you always have to start with a sphere with the Tool:Initialize settings set to HDivide: 32 and VDivide: 33. If an object doesn't have this exact topology, then it won't work for my purposes, so it just has to be this way. Now, there are many problems and many questions I have, but the one that's vexing me the most right now is this: apparently if I were to start with my 32x33 sphere and mold it into whatever shape I want (without adding or removing vertices), then subdivide and paint on it via PolyPainting, everything would be just fine (supposedly) when I convert what I've done to a texture. However, I'm experiencing the following problem. I have my model, at subdivision level 1 in all its chunkiness. It has 1024 faces. Because I want to create a texture for this model that is 512x512 pixels in dimensions, I subdivide four times to arrive at a model that now has 262144 faces, so that now I have exactly as many polygons in my model as I will have pixels in my final texture (512*512=262144). I now have 5 subdivision levels. I then paint the model while in subdivision level 5. When I'm done, I go to Texture and set the width and height both to 512. I also hit Texture:New, which creates a new texture that covers my model in a boring, plain color. That's fine, because my polypainting is still there underneath. So now I change back to subdivision level 1 and hit Tool:Texture:AUVTiles.That, I think, is where the problem occurred. I then return to subdivision level 5 and hit Tool:Texture:Col>Txr, and my texture takes on the lovely appearance of what I painted. Great. It retains its detail even when I go back down to subdivision level 1. Wonderful. I happily export my texture, and as I upload it to Second life I say to myself, "Huh, that's funny. The texture file I exported looks kind of chunkified rather than simply distorted like you'd expect." But since the final product looked fine in ZBrush, I thought nothing of it. When I tried applying my texture to the object in Second Life, it became clear that the texture was in fact chunky. Grid-like. Weird. Definitely NOT the way it looked in ZBrush. It's as if somebody took a perfectly normal texture map, cut it up into tons of tiny little squares, and then rotated those little squares in place so that the edges didn't match up with one another, giving the whole thing a weird sort of macro-pixelated look, if that makes sense. Here's a picture: ![shroom1.gif|512x512](upload://qT8DJVM3Y7OmHR2ye6Y9kkKA5oi.gif) It wasn't exactly a great texture to start with, but it certainly wasn't supposed to be THIS chunkified. I mean look, you can see little boxes! Anyway, I've been told by other Second Life users of ZBrush that if you hit "Make PolyMesh3D" more than once at the beginning of the whole game, it'll screw up your UV maps in a way that will make Second Life hate you. I've also been told that hitting ANY of the UV-related buttons in the Tool:Texture area will result in similar texture-screwing-up fiascos. Why would that be? Why are ZBrush and Second Life not getting along in this particular case here, and is there anything I can do to fix my current model (or its UV junk, if that's the problem?), which still looks great in ZBrush, without starting over from scratch, being extra careful not to hit "Make PolyMesh3D" more than once or hit any of the UV-related buttons in the Tool:Texture area? Is that even necessary? I've tried finding information on the web, but it's proving difficult, and the only info I've been able to get from other users in Second Life is borderline voodoo tips regarding ZBrush ("don't push that button or it'll screw things up" -- why???), and I just want to know how things work so I can get past the program details and start making things the way I want. It's frustrating to spend hours working on something just to have it fail. It's even more frustrating when you can see that it's working to some extent, but that ZBrush is just using textures in a different sort of format than Second Life. It's even more frustrating yet when you know that it's perfectly possible for ZBrush to use those textures in a way that's compatible with Second Life, but you have no clue as to how to force it to use that particular schema. Please, help me!! PS: The texture in question was for a glowing green mushroom. It was pretty crappy, but at least it was better than nothing.
#2

I solved my own problem by following the following instructions:

Re-Importing Uvs

Select the model you want to change UVs for in the Tool palette.
Set Tool: Geometry: SDiv to 1
Press Tool: Morph Target: StoreMT.
Press Tool: Import and navigate to the OBJ file with the uvs you want to import.
Press Tool: Morph Target: Switch

I don’t know what it did, but it fixed things up. I was able to make a new texture using the newly imported UV, and the exported texture looked the way it should, and it also worked with SL. Anyone know why this might be?

#3

I apologize for bumping this yet again when nobody has responded, but I wanted to clarify what it was that I had done to solve this problem.

Like I said, I followed the instructions above, which I found in the ZBrush help files. However, I forgot to specify the context in which I followed those instructions. Let me rephrase it in words more specific to my situation, so it makes more sense:

Re-Importing Uvs [i.e., getting back the default UV from the 32x33 sphere I had started out with, before I messed it up]

1. Select the model you want to change UVs for in the Tool palette. [i.e., select the model with the messed up UV's] 2. Set Tool: Geometry: SDiv to 1 3. Press Tool: Morph Target: StoreMT. 4. Press Tool: Import and navigate to the OBJ file with the uvs you want to import. [i.e., the OBJ file for a 32x33 sphere] 5. Press Tool: Morph Target: Switch

Works like magic.

#4

There are great tutorials and an app that helps export ZBrush sculpts as sculpties in Second Life over at http://www.shiny-life.com

#5

Unfortunately, I think I’ve already learned all I can from Shiny Life, but thank you anyway for posting the link!