Low Poly Model and UVs
With the high poly model done I started to get ready to do the retopology. Since this was a personal project I didn't have a polygon budget to match. I just wanted to end up with a really nice model so I didn't worry too much about the polygon count. The full model (with the gun and the jacket) sat at about 25,000 tris. Almost every part of the low poly model was made from scratch. Just a couple of things were made using geometry from the high poly model. I used Topogun to do the retopology. I really like this software because it's really simple and easy to use, and you can do the retopology really quickly.
I used Decimation Master in ZBrush to export a less dense high poly mesh to Topogun and did the retopology by parts (head, then pants, then shirt, and so on), always paying a lot of attention to the silhouette of the low poly. Always try to make it as close as you can to the silhouette of the high poly so that way you'll end up with a low poly that's really similar to the high poly and your maps will come out better when you bake them - not to mention you'll have less problems with the baking part.
Once I finished the retopology of everything (Fig. 08 - 09), I brought all the low poly meshes into Softimage to make some adjustments and tweaks that I find easier to do in a 3D modeling software.
When the low poly mesh was done I unwrapped the UVs. I decided to have four UV layouts so that way I could have a lot of resolution to work on the maps (diffuse, normal, specular, etc). That also allowed me to make almost everything unique (not mirrored).
The layouts are: one for the head, one for the body, one for the jacket and one for the gun. I unwrapped the UVs using UVLayout. That's another great piece of software that really makes things easier to do. I always try to hide the cuts of the UV on places that naturally have some "cuts", like the stitching on the pants and jackets. One thing that I like to do with the UVs that really helps when the texturing part comes is to straighten the edges of some parts of the model (Fig.10). That really helps with clothes and other parts where you need to put some kind of pattern on the texture (like a fabric pattern).