RMS 18
The Rib Archive Node

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Related Topics

    renderManArchiveNode
    RenderMan's RIB descriptions
    pre-baked RIBs

Introduction

The rendering of a Maya scene consists of two phases. During the first phase the geometries in Maya's scene graph are converted to RenderMan's RIB descriptions that are written to disk. During the second phase, Pixar's PRMan reads the RIB files and renders one or images.

Figure 1
Original object before assignement of a RibArchive node.

For complex geometries, phase one often takes a considerable amount of time. Particularly during look development a scene is repeatedly rendered and consequently time is wasted by the same RIB descriptions of complex non-deforming (unchanging) objects being written to disk over and over again. Maya displays what is being written to disk in it's lower left-hand corner - figure 2.

Figure 2
Writing RIB data or "caching"

Rib Archive Nodes enable phase one of the rendering pipeline to be streamlined by ensuring complex objects are only written once as a pre-baked RIB and are re-used by subsequent renders.

Figure 3
Bounding boxes show multiple copies of a RibArchive node.

Figure 4
Bounding boxes substituted by rib archives.

Step 1 - Adding a Rib Archive Node

1.1     Select the parent group of of the object to be archived.

     

1.2     From the RenderMan menu choose "Create Node and Write Archives".

     

1.3     In the Outliner notice a RibArchive node appears directly below the shape node.

     

Step 2 - Duplicating a Rib Archive Node

2.1     Duplicate the RibArchive node,

     

2.2     Create a null node by deselecting all objects and press control+g.
          Drag the duplicated RibArchive node to the null node.

   

Alternatively, drag the duplicated RibArchive node outside of it's original parent group, hilite it and press control+g.

   

Additional instances of the original object can be created by duplicating the grouped RibArchive node.
   

Step 3 - Updating a Rib Archive

Change the surface shader (material) of the original geometry.

3.1     In the attribute editor of the original RibArchive node select "Update Archive".

     

3.2     Select "Update look files only".

     

Re-rendering the scene will confirm all the duplicates have been updated.