Use Maya8.5 Transfer Maps Feature to Generate Normal Maps:

Introduction
Now Playstation 3 has arrived. New Generation of Games are arriving as well. One very important technique a 3D designer should know well is Normal Mapping. Before Maya 8.5, Maya uses a feature called "Surface Sampler" to generate normal maps. Now with Maya 8.5, "Suface Sampler" changed to "Transfer Maps" and brings alone a lot more useful features.

"Transfer Maps" uses two meshes, one is a high polygon count model with high quality details and another is a low polygon model. The idea is to transfer surface details from high polygon count model to the lower one by generating a map called "Normal Map". The map is then applied to the lower polygon count model, when the low-poly model was rendered, the details will be shown in the final render. It is very useful in a real-time game engine where lower polygon count means better game performance. 

As you can see from the "Transfer Maps" window, it has many more features than Normal Mapping. But for this tutorial, we will cover the Normal Mapping only. 

Models Used:

For this tutorial, I made a crocodile model. It was subdivided in ZBrush  and sculpted to get high quality details. The high-poly model has almost 1 million polygons and the low-polygon mesh is only 940 polygons. 

 


 

Steps to Create Normal Map and Assign it to Low-Poly Mesh:

1. You need to place two models directly on top of each other to begin with. Once you have placed the models correctly, select Low-Poly mesh, and go to Rendering Module, click menu Lighting/Shading Transfer Maps.

 

"Transfer Maps" window will pop-up and you can see the Low-poly mesh has been added in the "Target Meshes" section. (Note: you can add as many as target meshes you want, but Maya will only generate one normal map per operation.)

 

2. Select the High-Polygon mesh, and in the "Source Meshes" section click "Add Selected".

 

3. In the "Output Maps" section, select "Normal" as the type of map you want to create. As you can see, it will give you some options such as the location to store the generated normal map, File Format, Map Space, and etc. In this case, I set the Map width and Map height to 1024px.

4. Next in the "Maya Common Output" and "mental ray Common Output" sections, set both Map width and Height width to 1024px. I did not change any other attributes. But certainly you can explore with them. Maya's help file provides detailed information on those attributes. I set the "Sampling Quality" in "Maya Common Output" section to "High (8x8)", it will give you a Normal Map with very smooth result, of course, it will increase the processing time dramatically.

 

5. Click on "Bake and Close", it takes a while to create the map. At the bottom of the Help Line, you can see a pregress bar. Once it's finished, open the Attribute Editor for the low-poly model. You can see in the "Bump Map" channel already hooked up with the Mormal Map, in the bump2d node's "Use As" section, the "Tangent Space Normals" option has been selected. And in the texture file node, the colored Normal Map is nicely sitting there.

 


 


 

6. Time to prepare for rendering. I chose Mental ray in this case. One important note for rendering with mental ray is that you need to go to Render Setting window, select "mental ray" tab, go to "Tanslation" "Performance" tick "Maya Derivatives". This option should be selected, if not, in my case, I got some weired results.

Render Result:

The First one is the Low-Poly mesh in the viewport, and the Second one is the render result of the Low-Poly model with Normal Map applied.

 


 

Important Conditions for Using "Transfer Maps" Tools:

There are 2 conditions you need to satisfy before you use Transfer Maps feature.
1. All Target Objects must have clean and non-overlapping UVs.
2. Subdivision Surface and NURBS are not supported.