Rendering Using C_RayRender
C_RayRender is based on the vanilla Nuke RayRender node, but it also includes a Camera tab to reconstruct stereographic VR sequences using slit scan techniques. Ray rendering is a 3D to 2D process, so there's some setup involved before you can use C_RayRender.
When connected to a Scene node, the C_RayRender node renders all the objects and lights connected to that scene from the perspective of the Camera connected to the cam input (or a default camera if no cam input exists). The rendered 2D image is then passed along to the next node in the compositing tree, and you can use the result as an input to other nodes in the script.
C_RayRender is included with CaraVR as an alternative to Nuke's ScanlineRender because it is particularly suited to working with latlong material. C_RayRender can processes full 360 renders relatively quickly, and it includes a number of controls to improve the quality of stereo views towards the poles, when you look up or down wearing a headset.
Tip: CaraVR adds a tab to the Properties panel of Nuke's Write node allowing you quickly select groups of views such as stereo and cams when rendering previews or stitches. You can still select views manually using the views dropdown, but View Presets can make the process faster.