Rendering a shadow on its own and being able to composite it back in the final render allows you to edit a shadow’s blur, intensity, and color without having to re-render the entire scene. This can be a great asset when production time is limited. Shadow presets create an alpha matte of the shadows cast by objects in a scene.
Two shadow passes are available by default: the shadow pass and the selective shadow pass.
Shadow creates a shadow pass for the entire scene. It includes the following settings:
• Background Objects Partition—contains all of a scene’s objects. These objects have the Shadow shader applied to them via the partition. This shader only renders the shadows of every object in the partition.
• Background Lights Partition—automatically includes all lights for the scene.
Basic Selective Shadow Pass Settings
Selective Shadow creates a shadow pass only for selected shadow receiving objects. It includes the following settings:
• Background Objects Partition—contains all of a scene’s objects. These objects do not have the Shadow shader applied to them. Instead, shadow is applied via the shadow receivers partition.
• Background Lights Partition—automatically includes all lights for the scene.
• Partition Shadow Receivers—contains all of a scene’s objects that have the Shadow shader applied to them via the partition. This shader only renders the shadows of every object in the partition.
To set up a shadow pass or selective shadow pass preset
Before you start, remember that if you’re creating a selective shadow pass, you must first select the shadow-receiving objects that you want to include in the Shadow Receivers partition.
1. Load a shadow-pass preset from the Render toolbar by choosing Pass > Edit > New Pass > Shadow or Selective Shadow.
A shadow pass for the entire scene is created and the Shadow Pass property editor appears.
2. Set the active camera and rendering options.
3. If not already set, change the 3D view display type to view the render pass by selecting Cameras > Render Pass in the view’s Views menu.
4. You can further customize the shadow preset by renaming the pass and adding more partitions. See Creating Custom Render Passes.
5. When you are satisfied with the settings, preview the fully rendered frame by choosing Render > Preview > All Layers from the toolbar.
6. Render the pass. For more information on how to do this, see Rendering Methods.
Autodesk Softimage v.7.5