Procedure
To bake light maps with Arnold:
- Before starting the procedure, make sure that the scene renders look exactly as you would like. Any visuals that are rendering incorrectly in Arnold will affect the final maps.
- Whenever baking light maps, it is important to first create non-overlapping UV's. This ensures that light information won't be overwritten because some of the faces are overlapping in UV space.
Most light maps use Map Channel 2. Although the setting is not mandatory, it is a common practice of video game developers.
- Select a Physical Material for the scene. This is a well-featured material for rendering with Arnold.
- Select the objects that you want to use to bake light maps.
- Select to open the Bake to Texture dialog.
- If the available maps are hidden, click Show Maps to show them in the left pane of the window.
- Click the Add Maps to Selection button, and select the Color Common Map and Lighting maps.
The Lighting map is separate from colors and only contains light.
- Edit the map settings: press Ctrl+A to select all maps in the list, select UV Channel 2, set the Image size to the desired size (for example, 1024), and set the File Type to Bitmap (.BMP).
- Set Output to destination to Create a New Material.
- Assign maps to the material inputs of the material: in the Material/Map Browser, choose Standard (Legacy), and set the lighting to Self-Illumination, and connect the Color Common Map to the Diffuse input.
- Select an Output folder as the destination for the baked lights maps.
- Click Bake.
Light baking operations may take some time to complete. For better performance, you can adjust the settings in Arnold depending on the desired final quality.
- To view the final result on the Standard material, make sure to set the viewport to High Quality.
- Open the Material Editor to view the results. Note how a Shell material has been created, preserving the original Physical Material and creating a Standard (Legacy) material connected to the baked maps.