Blender UV maps

[sonosublime]

Hi all,

I am just taking the time to experiment a bit with UV mapping and the like in Blender (for eventual export to SFM). I have a couple of questions about painting skins for characters (whether they be TF2 models, or completely custom-made ones), and would greatly appreciate some advice.


1. Can anyone suggest any general rules or guidelines to follow when seaming a character model in Blender? I generally try to roughly separate different parts of the model (head, pants, shirt, jacket, strap, belt, shoes, hands etc) with seams.


2. After I seam and UV unwrap an object, I take a look at the UV map in the UV image editor. I have the different parts of the model all over the place, and would like to try and organise the UV map a little better before I try to colour it in, etc. So will moving the different islands (i.e. sections of the UV map) around affect anything?


3. When I am happy with the way the UV map looks, I generally apply the Blender colour grid to it so I can see which part of the UV map matches up to which part of the model.

I would like to export the UV map for painting a skin in Gimp/etc. Should I export the colour grid image, the UV layout, or both?

[Pte Jack]

1. If you are decompiling a character from a game already or have downloaded someones model in OBJ or any other format, 8.5 times out of 10 it will already have a map (especially if it's already painted. Suggestion is to study some texture that have already been made and see how the textures are laid out for things like the head and hands. Usually the head is seamed in the middle of the back of the head, the hands are halved horizontally top and bottom. The thing is you want your seams to be in an unconspicuous line. That way if the texture is under painted or doesn't quite meet properly because of a mesh warp, it's hard to see.

2. You should decide the size of the image you are going to use and create a template image before you unwrap your objects. This will keep your uvs restrainted to the size tof the image. Select all the mesh that is going to be on that image, assign it to a material and then unwrap. This should unwrap your islands on the material and they will be separated by the distance you give your island in the unwrap tool settings (When you press u to unwrap, check the tool area on the left of the screen for the setting, set that before clicking on the unwrap type. Once the mesh unwraps, you can select islands in the uv editor and scale ot move them as required.

3. This is personal pereference. The UV and Color grids are used to quickly paint your objects so that you can look the model over to see if the materials on the mesh are warping, stretching, shrinking and connect properly at the seams. you can use these to adjust mesh on the model so that it paints properly. If you export these into GIMP as you suggest, you can see the color coords and how they paint the model and apply your colors according to the grid layouts on a secondary layer. Jusr remember to turn off the grid layer before you export your newly painted skin. The UV layout is a representation of where mesh islands fall on the map, Using these as a template allows you to make sure your paint flows over the edge of the mesh (also known as over painting) and that you haven't missed anything.

[Pte Jack]

For example, This robot that I am working on only uses 2 materials. There are 23 objects that share these materials. I do have mesh islands that over lap or are on top of other islands, I just make sure that those islands are from different objects. The white materials is the material that i am using as the base for ALL the transparent objects. The colored mat is what is driving everything else. When I port this to SFM (and I already have an alpha model exported and working) it will only have 2 vmts assigned to it. http://imgur.com/PD7su1W

[sonosublime]

Thanks for your response.

1. I have tried looking at the Valve models in Blender for reference, and they seem to have UV maps. But for some reason, when I put the object into Edit mode, I cannot see any seams. Any ideas why?

Also, I seem to do ok when seaming a body. But for a head, I do seam in the middle of the back of the head, and the ears and eyes, but it does not quite seem to match up with a Valve head UV map, and looks quite warped. Are there other seams for a head that you can suggest?


2. How exactly can I decide on a size and create a template image when I am not even sure where I will be moving UV islands around to?


3. Yes, I think I plan to create a blank UV image, make it a colour grid. Then UV unwrap the object onto the colour grid. Then I will export the colour grid image and UV layout and then put them together in Gimp (on different layers). I will then create a new layer to paint the skin in Gimp, export the custom skin layer as an image file, and then convert it to VTF format. Does that sound like a viable strategy?

[sonosublime]

Bumping.

[Pte Jack]

SOMG, I thought I answered all that. Must have forgot to press post, or my hard drive failure happened as I was posting. Anyway, can't respond right now, I've managed to get into the failed drive and I'm transferring over 3,000,000 files to another computer.

[sonosublime]

No problem mate. And glad to hear that you managed to recover your data. Even if it is a lot of files to transfer...

And in the meantime, if anyone else wanted to provide some advice, it would be very much appreciated.

[R234]

Originally posted by sonosublime:

I have tried looking at the Valve models in Blender for reference, and they seem to have UV maps. But for some reason, when I put the object into Edit mode, I cannot see any seams. Any ideas why?

Because Blender's SMD importer does not support importation of seams. Or sharp edges for that matter, so smoothing groups have to be redone. Seems to be a limitation with how edge data is saved in Source model files or whatev's.

[sonosublime]

Thanks for answering my first question, R234. That's useful to know.

[ConfederateJoe]

Just be sure to apply any geometry/modifiers before UVing to avoid possible issues.

Also, don't break your balls trying to texture from a UV map in like photoshop of whatever. The dark ages are over, become acquainted with texture painting! Blender is not very good at this sadly. You'll probably be sticking to just colors and basic textures come to think of it...

When it comes to UVs, they can be as terrible looking as your skill permits, the important thing is that you can identify islands and the space per poly is about the same across the board. Just make sure that it's neatly and proportionally laid out. Think about it this way. You have a knife, and you want to cut your mesh so you can lay all the surfaces out. You'd cut a certain way to do this.

[sonosublime]

1. Ok, so you're saying that all modifiers should be applied before UV unwrapping takes place?

Also, what exactly is texture painting?


2. I've been told that I should decide the size of the image I am going to use and create a template image before I unwrap your objects. But how exactly can I decide on a size and create a template image when I am not even sure where I will be moving UV islands around to?

[ConfederateJoe]

1. When it comes to exporting to SFM, yes, usually this is not really necessary.
Texture painting is painting textures/colors and other various image maps in and onto 3D meshes, it's a more streamlined way to texture things. All the cool kids are doing it these days :P

UV maps are not bound by size, they just let the computer know what images go where on the 3D mesh. just do 2048x2048, it's a fine size. The size of image maps almost always have the same value of height and width.

[Pte Jack]

The thing about Valve materials is that your UV paints must be to the power of 2 in order to be able to be converted to VTFs. So, 64x64, 256x64, 64x1204, 512x512, etc would work, 641x1025 would not, because the values are not to the power of 2. 2, 4, 16, 32, 64, 128, 256, 512, 1024, 2048, 4056, etc...

[sonosublime]

Thanks for your replies.

1. So by texture painting, you mean painting directly on the UV layout in the modelling software in question (in this case, Blender)? I actually do plan to do that a bit. Once I UV unwrap the Blender object, I open it onto a colour grid to get an idea of how things match up. I then use Paint Mode in the Blender UV image editor to do some rough painting of colours, and then export the image and UV layout for touching up in a 3rd party program like Gimp.

Does this seem like an acceptable technique?

Also, after I have done some painting, is there a way to change the UV image from a colour grid back to a blank black image without losing the painting that has been done?


2. Thanks, I've been told about those power 2 sizes. However, 2048x2048 seems pretty large. I've done a test by exporting 256x256 and 1024x1024 images from the UV image editor, and the size of the image file increases exponentially as the image size increases. Will this have an impact on the model size and/or performance in SFM?

[Pte Jack]

If you are thinking of not only getting these assets you're planning into SFM but into TF2 as well, here is a guide lines list that you might want to look at. These guidelines should serve as the requirements for SFM as well as SFM in its current state is based off the TF2 World.

http://www.teamfortress.com/workshop/

[sonosublime]

2. According to that link you sent, 512x512 should be a good size to make use of for a template image, is that correct? Even for a full TF2-sized character? And 256x256 for small items (hats)?


Also, I have a new question:

3. Are there any general rules of thumb to follow when painting the texture/skin for a character? i.e. shading, human skin colour, etc?