PAINTING TEXTURE MAPS TUTORIAL
Firstly in order to do this part of a 3D Model, you will need to have the UVs of you model laid out. Refer to the UV mapping tutorial if you have no idea how to do this. But if you do have your UVs laid out first look over them to make sure that they are within the 1 to 1 area. There are more advanced techniques that allow for repeating texture maps so the UVs can be outside the 1 to 1 but for now lets keep it straight forward. Next make sure that your UVs are going to do what you need them to do. Meaning if you need a symbol on the left shoulder and not the right then you will need to duplicate you half mesh on the negative and combine it with the other half, donít forget to merge verts. Then you can go into you UVs and flip or move the left shoulder UV shell so it is no longer right on top of the right shoulderís UV shell.
So now our UV set is the way we want it, save out a snapshot of your UVs and bring that snapshot into Photoshop. Iím using Photoshop but you can really use any paint program as long as it is for production quality material, not software like MS Paint. Also you can work at any resolution you want to but the important thing is to keep the texture to a square ratio. Good ones to use are, 512 x 512, 1024 x 1024, 2048 x 2048 and 4096 x 4096. And a good rule of thumb is to work bigger than you final results. If I was working towards a 2K map or 2048 x 2048, then I would want to do my texture at 4096 x 4096 then save out the shrunken version. I found this make the texture much crisper and colors much brighter and varied.
After that I look to find textures from both photo resources and texture archives. Yes you can paint your textures by hand, but if you are not a Master oil painter then you probably canít paint realistic cotton textures.
There are really good websites and resources to purchase high res photos for texture reference. And of course you can go a take your texture references with you own digital camera as well.
Where ever you get you textures from be sure to watch for seems in your model. Where two shells meet in your UV map will create on your mesh a seam, and this will take the most time to ďpaintĒ out. Seams on a modelís texture are the ugliest thing you could possibly do, yet when playing video games you see them all over the place. This could be from only two reasons, not enough time to fix it or the more likely, the artist didnít know how to.
Iíve found the quick way towards a seamless texture and model is this technique. First always paint past you edge in you UV map. Then with you lasso tool select what is outside the edge and some past the edge, copy that and place what was outside the edge on the inside the other edge on the opposite side of the seem. Then it is just a matter of going back and forth with the clone stamper to blend out the texture nicely.