Rfm ( renderman for maya ) Secondary outputs (AOV) and render Passes

Rfm ( renderman for maya ) Secondary outputs (AOV) and render Passes

from the RFM docs

Ambient

The total contribution from ambient light sources 

Backscattering

Total contribution of backscattering effects

DiffuseDirect

Unoccluded diffuse response to direct lights

DiffuseDirectShadow

Diffuse response that is shadowed (subtract this from DiffuseDirect)

DiffuseEnvironment

Diffuse response from environments

DiffuseIndirect

Diffuse response reflected from other objects

Incandescence

Total contribution of incandescent effects

Refraction

Total contribution of refraction effects

Rim

Total contribution of rim effect

SpecularDirect

Specular response from direct lights

SpecularDirectShadow

Specular response that is shadowed, subtract this from SpecularDirect

SpecularEnvironment

(Unoccluded) specular response from environments

SpecularIndirect

Specular light reflected from other objects (coherent reflections)

Subsurface

Total contribution of subsurface scattering

Translucence

Total contribution of cheap/thin translucence

The recipe for compositing your beauty image is a simple additive process using these outputs:

 result = SpecularDirect - SpecularDirectShadow + SpecularIndirect +
   SpecularEnvironment + Ambient +
   DiffuseDirect + Translucence - DiffuseDirectShadow +
   DiffuseIndirect + DiffuseEnvironment + Backscattering +
   Subsurface + Rim + Refraction + Incandescence
 

Additionally, there are “ancillary outputs” that are not used to create the beauty render but can be useful for other compositing tasks:

SpecularColor

Color used to scale specular illumination

DiffuseColor

Color used to scale ambient and diffuse illumination

OcclusionDirect

Occlusion of direct illumination (shadows)

OcclusionIndirect

Occlusion of indirect (ambient) illumination

N

The unnormalized shading normal at the shading point in Camera Space. For visualizing in rgb space, N must be normalized.

Ng

The unnormalized geometric normal at the shading point in Camera Space. For visualizing in rgb space, Ng must be normalized. Ng is the actual normal of the surface, while N is the normal used for shading. If there is anything perturbing the normal for shading these will be different.

P

The coordinates for the surface point in camera space.

s, and t

The 2D texturing coordinates at P. These are by default u and v, but can be overridden.

u, and v

The 2D texturing coordinates at P.

Cs and Os

The color and opacity of the surface before shading.

Ci and Oi

The output color and opacity of the surface after the shader runs.

a

The alpha at the surface point.

dPdtime

Derivative of P in time. Simply put, this outputs the velocity vector.

__CPUtime

The total shader runtime for the shading grid that the point is on. This is very useful for optimizing shading time for a scene.

Currently working on render pass info, the changed the names of the outputs in renderman, and i am trying to figure out which passes are what, because they arent as straightforward as they seem.
Here is what im looking at,
DiffuseColor - just the flat color values, no shading, shadowing or highlights
DiffuseDirect - Color values with shading, no shadows or highlights
DiffuseDirectShadow - Shadow Pass
DiffuseEnvironment - Seems to be the diffusecolor mixed with the occlusion pass?
Refraction - Refraction :D
SpecularColor - This returns the actual value set for the specularColor in maya it seems, note this is across the whole object/shader, no highlights just the value for the COLOR of the highlights.
SpecularDirect - standard Specular highlights pass
SpecularDirectShadow - Unsure, it has detail where highlights are, they might be added to the diffusedirectshadow pass to get the full shadow pass?
SpecularEnvironment - Seems to be an alpha which masks out reflections from the specular highlight, dont know where to use it.
SpecularIndirect - Reflection Pass
OcclusionDirect - an alpha based on the shadows but without varying levels, so parts are completely white, i couldnt find a way to use it in a comp.
OcclusionIndirect - Occlusion map, if you invert this it is a regular ambient occlusion style map.

Ambient - Light from any ambient light in your sene. N - Surface normals in Scene, can be used to adjust or add lights in post
Ng - Geometric Normals, i dont know the difference between the two normal passes, but i think the N is the one usually used (i dont know where i heard it but i think thats what i heard :D )
Oi - An alpha for the scene
Cs - Another Alpha
Os - Alpha for the scene again
A - Another Alpha fo rthe scene, maybe it has harder edges?/ no aa?
T - Depth map
S - Inverted Depth map?
P - Basicly a a purple, white, blue and light blue tartan style ramp? no clue really what this could be used for
U - looks similar to a depth map, but with everything getting dark from right to left. this is based on the U coords as i understand
V - Same as above, but objects get darker as the go down based on V coords.

I hope this helps!