2. The occlusion trick
This part will be something more of a tutorial about using ambient occlusion and texture baking during the texturing process. Everything here is done in vray, but I'm quite sure that other renderes also have the options to render AO and bake textures.
Firstly, the basics
In my previous making of ( http://188.8.131.52/team/Tutorials_2/Battle_Toaster/battle_toaster07.asp
) I've shown you how to make an ambient occlusion pass. This is the base for this tutorial. You need to put the ambient occlusion material on the whole model.
is the tutorial I've used to learn about texture baking in vray. I think the tutorial is well written so I won't repeat the material covered in it :) You need to focus on the "Preparing Objects for Baking the Textures" part with one very important difference. If you want to use the baked texture in Photoshop you will need to make UV manually, so that it bakes into a nice layout. To avoid using automatically generated mapping coordinates you need to check "Use existing channel" in the mapping coordinates section.
Ok, these were the basics, but.. what is it all about, why not use the good old textporter?
Well, in complicated technical models that consist of lots of parts it's often hard to paint a precise texture. You need to check where parts are touching each other and be careful not to miss those spots on the texture. And here the ambient occlusion comes in. Thanks to this mechanism, you will see where things are close to each other and where they connect. Let me explain this on the following example:
This is the texture of a minigun hull (I've changed 100% black to 100% white). Thanks to AO I can now clearly distinguish the barells (1), the bottom support (2), the gun lock (3) and other parts. Using these outlines I don't have any problems with aligning textures on the model.
Another, more obvious use of the ambient occlusion outline for texturing is to create dirt maps out of them (or to use them as masks for real dirt textures).
As you can see, even though this method of generating UV layouts takes more time than usual (because of baking the AO outlines), it is possible to create your textures with greater precision.