SUMMARY
This article explains how to define render passes in Katana and utilize renderer specific options.
MORE INFORMATION
To render your Katana project into a final image result, you need to define which render passes (also known as AOV passes and LPE passes) you want to output. This can be done using the renderer specific node that defines the passes, together with the RenderOutputDefine node that configures output settings for the final image.
More information on setting up a render pass can also be found in our Katana User Guide.
Render passes can range from Light Path Expressions (diffuse, specular, transmissive, subsurface layers, etc.) to more complex AOV layers (deep layers, motion vectors, scripts etc.)
How you set up render passes varies between renderers. However, in most cases you will need to use one OutputChannelDefine node prefixed with the renderer name (e.g. PrmanOutputChannelDefine) and one RenderOutputDefine node for each render pass.
Here are the current renderer specific nodes:
- 3Delight = DlSettings
- Arnold = ArnoldOutputChannelDefine
- Redshift = RedshiftOutputChannelDefine
-
Renderman = PrmanOutputChannelDefine
Setting up AOV & LPE passes
Each rendering system used in Katana has a unique way for setting up custom AOV and LPE Render passes.
Katana ships with example projects for 3Delight, Arnold and RenderMan, which will help you to understand how to set up AOVs for your project.
To access these example project, open Katana and head to:
Help > Example Projects > Other Technical Examples > Secondary Images (AOVs)
3Delight
3Delight uses a SuperTool to set up AOVs called DlSettings. This SuperTool holds 3Delight's render settings and image layers inside one node, making it unique when compared to the other renderer OutputChannelDefine nodes.
For more information on 3Delight's DlSettings SuperTool, please find their documentation below:
3Delight DlSettings Super Tool
Arnold
Arnold offer documentation on their ArnoldOutputChannelDefine node in their Arnold User Guide under:
Arnold For Katana - Global Settings - Channel Definitions
Another useful community post describing how to set up an ambient occlusion pass is:
Foundry Community Forum - Setting up Arnold Ambient Occlusion pass in Katana
RenderMan
RenderMan provides documentation on how to set up the PrmanOutputChannelDefine node options and AOV & LPE expressions at the following links:
RenderMan's PrmanOutputChannelDefine
RenderMan Arbitrary Output Variables
RenderMan Light Path Expressions
RenderOutputDefine node overview
Information on how to create a new render output or override the settings for an existing one can be found in the Katana User Guide under: Defining and Overriding a Color Output
The parameters of the RenderOutputDefine node are also described in the Katana Reference Guide under: Reference Guide > 3D Nodes > RenderOutputDefine
Setting up a custom render location for your render layers
To set up a custom render location, you need to select the 'locationType' parameter in the RenderOutputDefine node, and toggle it to 'file'. This will expose the 'renderLocation' parameter and let you define a custom file path.
If 'locationType' is set to 'local', then the render layers will be saved in your machine's temporary directory defined by the KATANA_TMPDIR environment variable. You can find more information regarding this environment variable in the Katana Developer Guide here: Environment Variables - Caching and Temporary Files
If you are using an asset management system, then the location would be driven by the asset management implementation.
Below is an example screenshot of a RenderOutputDefine node with a custom render location defined:
Setting up render passes through a GroupStack
When you work with a large number of render passes, a great way to organize them is to keep all your RenderOutputDefine nodes compacted into a single GroupStack node.
Here is a screenshot example displaying a list of stacked passes in the GroupStack node:
Nodes can be added from the Node Graph to the GroupStack, by holding the Shift key and using the middle mouse button to drag your node into the stack.
If you would like to know more about the GroupStack node's parameters and uses, please have a look at our Katana Reference Guide under Reference Guide > Miscellaneous Nodes > GroupStack.
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