Pixar's Renderman: Analytic Lights and PxrMeshLight

 When I was learning Pixar's Renderman for my student film Delivery, during my research I learned about analytic lights and how they effect render times.  I am not a lighting artist but its still very good to know how Renderman calculates lights especially if you have a special case that is uses lighting differently. 

The primary mode of lights in renderman are called analytic lights because they are economical to render time.  They are highly mathematical modeled lights, highly efficient, and they use aerial lights.  Thus they are calculated cleaner and give us a faster result. 

    Analytic lights include:

• PxrRectLight
• PxrDiskLight
• PxrDistentLight
• PxrSphereLight
• PxrDomeLight
• PxrPortalLight
• PxrEnvDayLight

Autodesk Maya 2022 Renderman's Analytic Lights

An example of a light that isn't analytic is the PxrMeshLight.  If you use this light, you won't get the same speed and cleanliness in the scene.  What the PxrMeshLight does is it makes objects emissive.  It's better than a glow material but it is not economical like analytic lights.  This does not mean to not use this light, sometimes you do need to use this light for objects that are illuminating.  

How to use the PxrMeshLight: 

1. Select an object in your scene.
2. Select it's icon on the Renderman shelf. 
   
   

    3.  To edit it's settings, simply click on it's node under the object you put it on in the outliner. In the channel box you can edit each of the settings. 

Gif of Autodesk Maya 2022 Applying the Renderman's PxrMeshLight

Autodesk Maya 2022 Example of Renderman's PxrMeshLight