---
title: "PxrAOVLight in Blender"
canonical: "https://rmanwiki-27.pixar.com/space/RFB27/544638999/PxrAOVLight%20in%20Blender"
format: markdown
---
![eyes_slide3.jpg](media://6994e65c-4adf-4c16-9cce-8c1a679abe23)

The [PxrAovLight](https://renderman.atlassian.net/wiki/spaces/REN26/pages/19661731) is a handy utility light that allows a lighting artist to output a shot-specific AOV mask without needing to request one from the shading artists. 

In this example, we'll break down a common request ... getting a refraction AOV for a character's eye  
(sclera or iris inside a cornea).

![RenderMan_AOVLight_1.JPG](media://1c98af72-1ae7-41ac-b43b-0bf230b34b45)

![RenderMan_eyeball.jpg](media://9389603c-6217-42e7-b688-e236dff8780e)


### Creating the PxrAOVLight

The first thing we need to do is to create a PxrAovLight, which can be found in the RenderMan viewport panel under Add Light → PxrAovLight.

![RenderMan_AOVLight_2.jpg](media://583e8fa4-f0c3-49cb-b8b0-ba774082551e)

Once created, we now need to set up the PxrAOVLight.

- Give your AOV a name, here we have used *irisMask*
- Set the “Use Color” attribute to on because we are writing to a color AOV.
- Since PxrAOVLight isn’t technically a light that illuminates the scene, we can turn off the “primary visibility” attribute.
- The “In Refraction” attribute is on because we need the rays to go through the cornea and hit the iris geometry.

![RenderMan_AOVLight_3.JPG](media://8fa4e5fc-6490-4907-b569-1edf0edac5b2)


### Light Linking

Next, open the Light Linking tool, again, one place this can be found is in the RenderMan tool panel.

We use [light linking](https://renderman.atlassian.net/wiki/spaces/RFB27/pages/544637371) to include/exclude pieces of geometry in the AOV. 

In this example, the PxrAovLight is on for the Iris_GEO and off for the other parts of the eyeball.  
This linking setup creates a mask of the Iris inside the refractive cornea. 

![RenderMan_AOVLight_4.JPG](media://81da4316-8a7a-41d6-8982-9079ad5f9a58)


### Defining the Output AOV

Once you have set an AOV Name in the PxrAOVLight attributes, use the [AOVs Manager](https://renderman.atlassian.net/wiki/spaces/RFB27/pages/544639742) to define a new display to which PxrAovLight will write the data to.

Note: Make sure the names match, like so:

|  |  |
| --- | --- |
| **PxrAOVLight** | *MyAOVName* |
| **Channel Source** | *MyAOVName* |

In this example, we used *irisMask *as the PxrAOVLight AOV name and the Channel Source name.  
  
Here, we’ve created a new display called **Iris**.  
Under **Iris**, we created a new channel called **irisMask** which must be the same AOV name we previously chose for our PxrAOVLight.

The AOVs Manager setup will look something like this:

![RenderMan_AOVLight_5.JPG](media://ef72731b-14a6-4f07-b6ba-e97f0a4b1a66)

And here’s the render of the irisMask AOV … Magic eh?!

![RenderMan_AOVLight_6.jpg](media://eda7cda3-7b18-4ed3-90ca-d6ebbb635b78)


### Compositing

We can now use this mask inside compositing software to make further post-production adjustments. In Nuke, we have shuffled out the irisMask AOV into an alpha and used that as a mask input for a HueShift node to re-color the iris.

![RenderMan_AOVLight_7.JPG](media://59e702b6-36af-4824-a077-92cea4aa6e10)