3. Export the individual parts into ZBrush and start working on the fine details. It is good to remind yourself on what kind of details you should be working on, and do not go into too small details such as veins unless you feel that it is absolutely needed. However, they usually won't show on your normal map and they will just increase the polygon amount.
You can always add the small details later in Photoshop when you know exactly how much UV/texturespace you have for that particular object.
4. Keep an eye on the polycount as you do not want to work on something that's too crazy a size. After detailing, export the mesh at highest level. Work on each of the parts this way until all of your initial highpoly have been turned into "high detail" ones.
Compiling, Final lowpoly and Baking
1. After all of my initial highpoly have gone through the ZBrush treatment, I started bringing the .obj files into Max. The next step greatly depends on your computer power.
My system was unable to handle all the models at the same time so I had to eventually break down the character into 2 files. One for accessories and the other for core parts of the character. Use layering so you can choose on what parts to display and hide.
2. Now start working on the lowpoly. This is where I faced most of my problems as I was totally new to normal mapping. Build your lowpoly to suit the highpoly, and add polygons where needed. Sometimes you might need to take test bakes if you are not sure if it is working. At this stage, you can still decide what can or need to be mirrored and what objects can be duplicated to save more UV space. Later on you will get the feel on where to place polygons to get the optimum bake solution.
After all my lowpoly objects were done, I unwrapped and attached them together so I could work on the final UV layout. I used checker texture which is a great way to see how your unwrap is working.
After everything is done, I detached the lowpoly objects again.
Now at this point, my computer was dying on me and I had huge problems (such as ctrl+z crashing the software) so I highly recommend that when you are baking, make a new file and then merge the highpoly and lowpoly objects from the file which you compiled everything in, so that you can work on just the part that you want. Obviously this stage depends on your computer's capacity.
At this stage, I assigned basic materials and colours for my highpoly objects. This will help you when you start to work on the textures.
I used the Render To Texture feature in Max to bake out maps such as Normal, Diffuse, Specular and Height. I used Max8 and for some reason, I could not get the Ambient Occlusion pass to work, and hence extra setting up was needed for this stage. Also, do keep in mind that this eats a lot of memory, so you might need to bake up in batches such as (normal, height) (diffuse, specular) (Occlusion). Personally, I feel it is a good idea to make presets for your rendering needs as you will be swapping between MR (to bake all the other maps) and Scanline (to bake the Occlusion).
I would suggest naming all your objects before you start to bake, so that the RTT menu will automatically name the maps with proper names.
1. First, make sure you do not have any lights in your scene. Then, create one Sky Light anywhere on the scene.
2. Change to Max Scanline renderer and enable light tracer. (Basic setup should work just fine.)
3. Render a Lighting pass. Now you should have a nice Occlusion map without any artifacts or black spots.