Render Elements or Render Passes allow for the rendering of specific elements of a render to be separated into different images which can then be recombined in a compositing program such as Nuke or After Effects for tuning after the render is complete. For example, a render pass can contain just the reflections on a surface, or just the diffuse lighting, or just the masks based on shared materials etc. The passes can be viewed individually in Maya’s IPR window.
The Render Passes are accessed from the Render Settings window in the OctaneRender Settings tab. There are six sub-categories of render passes. Figure 1 shows the passes in the Render Setting window.
- Beauty passes
- Post processing passes
- Render layer passes
- Lighting passes
- Info passes
- Material passes
Figure 1: Render Passes are separated into categories in the Render Setting window under the OctaneRender Setting tab.
Producing Multilayer EXR from OctaneRender for Maya
Saving files is a standard setting in Maya and it uses this information for output regardless of the render engine. Due to restrictions in the standard image-saving functions in Maya, the plugin is forced to use its own OpenEXR library. As a result, with OctaneRender, the plugin will always render and produce OpenEXR files regardless of the format chosen from Maya’s standard list. To produce Multilayer EXR from Maya, users can choose any of the 16 bit file format in the Common tab (i.e. Maya16, SGI16, Tiff16). Choosing one of these formats forces the plugin to produce an EXR output. If the render passes are enabled, these passes produced at render time are also added to the resulting multilayer EXR file. The passes can then be extracted within compositing software. Figure 2 shows the image format menu in the Common tab of the Maya Render Settings window.
Figure 2: Specify the image format in the Common Tab of the Render Setting window.
After choosing a 16 bit image format the Save Composite EXR file option must be activated in the Additional section of the OctaneRender Settings tab. (figure 3)
Window -> Rendering Editors -> Render Settings (Render Using OctaneRender) -> OctaneRender Settings -> Additional rollout
Figure 3: Turn on the option to save composite EXR files.
Video Tutorial: Rendering Multichannel EXR Images