3. Model Testing
When you are happy with your model import the high resolution version. Its important to have the full version of this car and not just half or, when you come to generate a normal map, it will have a line down the centre.
What you need to do now is test the topology, making sure the surface will look as good as it can when a normal map is applied.
If using Maya apply quick and dirty UV`s to the optimized model using the Automatic Mapping tool. Now you can generate a quick normal map to fully test the model.
To generate the normal map use the Transfer Maps tool found under the Lighting/Shading menu.
Under “Target Meshes” add the low polygon game model.
Under “Source Meshes” add the high resolution model.
Under “Maya Common Output” set the “Sampling Quality” to preview while you are working to generate quicker maps.
Remember to keep both models in the same world space!
What you should have now is the low resolution model with the normal map applied, looking smooth and detailed! Its at this stage you can rework areas of the model, optimize further or tweak the topology. This will effect the normal map but when you want to test the surface again just apply Automatic Mapping again and throw out another preview normal map.
Continue on like this for as long as you like.
NOTE: If working on a hard surface which will have elements that will be seperate, car doors for example, you can use the normal map to guide you as you cut around the seams. It is important to keep these edge normals hard though so the normal map will look the same when they are detached.