Ascension: Light Map UV Sets

Creating a 2nd UV set for a Models Light Map

This tutorial assumes the reader has intermediate knowledge on how to UV polygonal models using Maya. In it I will show how I create and layout a 2nd UV set for use as the model's Light map.

Step 1: Select the model you’d like to create a new Light Map for. I've chosen this wall section for the Mars Colony Space Station.

Step 2: Create a new UV set for your model using an Automatic Map

Polygons – Create UVs – Automatic Mapping Options

Select the following options:

• Planes: 6
• Optimize for: Less Distortion
• Shell Layout: Into Square
• Scale Mode: Uniform
• Shell Stacking: Bounding Box
• Spacing Presets: Change this to the size map you’re going to use
• Create New UV Set: Yes
• UV Set Name: LightSet

Step 3: Navigate to the UV Texture Editor, and select all edges, then Cut UV Edges

UV Texture Editor - Cut UV Edges

Step 4: Select all edges, then use the Layout Options

UV Texture Editor - Layout

Select the following options:

• Layout multiple objects: Non-overlapping
• Shell Layout: Into Square
• Scale Mode: Stretch to Square
• Shell Stacking: Shape (Note that when I took the screenshot, I still had bounding box selected. Using Shape as opposed to Bounding Box appears to produce better results)
  
• Rotate: None
• Spacing Presets: Change this to the size map you’re going to use

My finished product is shown below, yours should appear similar. Unlike a color or normal map, our UV edges don't necessarily need to lay out together. This is because we will be using a Batch process to generate the lighting. To create your new light map, add lights and do a Batch Bake using Mental Ray. Hope this is helpful!