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Introduction

Redshift has a number of integrated AOVs that require little to no additional setup to get started. We'll demonstrate the use of these integrated AOVs using the example scene below which includes most common shading elements (diffuse, translucency, reflections, refractions, bump mapping, normal mapping, SSS), several different light sources, environment lighting, global illumination, and caustics.

Where the scene does not already contain the shading elements needed to cover particular AOVs (emission, volume rendering, motion vectors) small changes will be made in order to demonstrate these AOVs.

AOV example scene

AOV Workflow

There are essentially two different methods of working with AOVs in Redshift. A more simple method that makes use of fewer AOVs and a more complex method that requires several more AOVs but allows for greater control over individual shading elements. The more complex but more flexible method of working with AOVs involves additional "raw" type AOVs that isolate shading elements down even further, like separating the color component of a material from the lighting contribution in the scene. By comparison you might consider the more simple method the "standard" or "non-raw" workflow. 

Both methods are capable of perfectly recreating the primary beauty render so it's just a matter of choosing what works best for you and your project. We will cover both methods below but the raw AOV's separately to reduce confusion. 

Standard Shading Elements

Diffuse Lighting

Diffuse Lighting AOV
The Diffuse Lighting AOV contains the diffuse and translucency lighting component of the material's final shaded result. Typically, diffuse lighting reaching a material is multiplied by the material's diffuse color. The Diffuse Lighting AOV returns this multiplied result.

If this multiplication is not desired, you can use the Diffuse Lighting Raw AOV, instead, which returns the non-multiplied diffuse lighting.

The Diffuse Lighting is tinted by each object's material diffuse color. The Diffuse Lighting Raw looks almost black and white because it contains only the light color and intensity information without the multiplication with each material's diffuse color.

The Diffuse Lighting AOV already includes a renders Translucency component. If you need to isolate the Translucency component from the Diffuse Lighting AOV please see the raw AOV workflow here.


Lighting from emissive materials is visible only in the Global Illumination AOV. For more information, please see here.

How to use: 

Add the Diffuse Lighting AOV to the primary AOV composite stack. 

Reflections

Reflections AOV
The reflections AOV contains the reflection component of the final shaded result. Please note that the reflections do not contain the reflections of lights also known as specular reflections): these are contained in the specular AOV. The example scene is lit by an environment shader so environment reflection shows prominently on the table here in the reflection AOV. 

How to use: 

Add the Reflections AOV to the primary AOV composite stack. 

Specular Lighting

Specular Lighting AOV
The specular lighting AOV contains only the lighting component of the final shaded result. Please note that by 'specular lighting' we mean the reflections of lights only. This is demonstrated in the picture above. The example scene is lit by an environment shader which does not act as a light so the environment reflection shows up in the reflection AOV rather than the specular AOV. 

How to use: 

Add the Specular Lighting AOV to the primary AOV composite stack. 

Refractions

Refractions AOV
The refractions AOV contains the refraction component of the final shaded result. In the example scene pictured above you can see how the refractive drinking glass dominates this AOV since any ray that passes through the drinking glass is considered a refraction ray at that point.

How to use: 

Add the Refractions AOV to the primary AOV composite stack. 

Sub Surface Scatter

Sub Surface Scatter AOV
The Sub Surface Scatter AOV contains the subsurface scattering component of the final shaded result. In this scene only the lemons have any sub surface scattering element to their shaders and that is displayed here.

How to use: 

Add the Sub Surface Scatter AOV to the primary AOV composite stack. 

Caustics

Caustics AOVCaustics AOV Exposure +4
The caustics AOV contains the caustics lighting component of the material's final shaded result. In the example scene pictured above the caustic contribution is relatively low so an additional image is provided of the same Caustics AOV but with a boost to exposure by +4 so that you can see it more easily. 

How to use: 

Add the Caustics AOV to the primary AOV composite stack. 

Emission

Emission AOV

To demonstrate the Emission AOV the example scene has been modified to include emissive elements. Every material in the scene except the drinking glass, liquid, and table have had their diffuse color linked to the emission port with their emission weight set to 2.

The Emission AOV only contains the flat emissive color component of each shader with no lighting information. As far as scene lighting goes, emission only affects the global illumination lighting component of your scene and it is there where you will find any lighting changes based on emission.

Below you can see a side by side comparison of how adding emission to the scene affects the beauty and different AOVs. In the case of the diffuse lighting there is no change at all. 

Beauty compareDiffuse Lighting compare (no change)Reflection Compare



Refraction compareSSS compareGI compare
How to use: 

Add the Emission AOV to the primary AOV composite stack. 

Global Illumination

Global Illumination AOV
The global illumination (GI) AOV contains the indirect GI lighting component of the material's final shaded result. The GI lighting reaching a material is multiplied by the material's diffuse color. The GI AOV returns this multiplied result.

If this multiplication is not desirable, you can use the Global Illumination Raw AOV, instead, which returns the non-multiplied GI. Please see here for more information on raw AOVs.

How to use: 

Add the Global Illumination AOV to the primary AOV composite stack. 

Volume Lighting


Volume Lighting AOV

To demonstrate the Emission AOV the example scene has been modified to include emissive elements. Every material in the scene except the drinking glass, liquid, and table have had their diffuse color linked to the emission port with their emission weight set to 2.

The Emission AOV only contains the flat emissive color component of each shader with no lighting information. As far as scene lighting goes, emission only affects the global illumination lighting component of your scene and it is there where you will find any lighting changes based on emission.

Below you can see a side by side comparison of how adding emission to the scene affects the beauty and different AOVs. In the case of the diffuse lighting there is no change at all. 




Beauty compareDiffuse Lighting compareReflection Compare






Refraction compareSSS compareGI compare
How to use: 

Add the Volume Lighting AOV to the primary AOV composite stack. 

Background

Background AOV
The Background AOV contains the backplate and background component from things like a Redshift Environment shader or Domelight. 

In the example above an environment shader is used.

How to use: 

Add the Background AOV to the primary AOV composite stack. 

Compositing Standard AOVs

Nuke


A basic example of how to composite the standard shading component AOV's in Nuke, all layers are added together using a "Plus" node

After Effects

A basic example of how to composite the standard shading component AOV's in After Effects, all layers use blending mode: "Add"

Fusion

A basic example of compositing standard shading AOV's in Fusion, all image loaders are added together with a Merge node with "alpha gain" set to 0



Raw Shading Elements

Diffuse Filter & Diffuse Lighting Raw 

Diffuse Filter AOVDiffuse Lighting Raw AOV
The Diffuse Filter AOV contains only the diffuse color contents of a shader without any lighting contribution. Any material that performs diffuse lighting typically has a diffuse color port which can be textured, set to a constant color, or connected to an elaborate shading graph. The diffuse filter AOV in conjunction with 'raw' lighting AOVs allows the user to tweak the lighting results separately from each material's diffuse color.

The picture above shows the diffuse color of each object. Notice that the the objects are not purely diffuse but actually have a bit of reflection on their silhouettes (Fresnel effect). For this reason, the diffuse component is a bit dimmer around their silhouettes since reflection 'takes away energy' from diffuse lighting.

How to use:

Multiply the Diffuse Filter AOV by the Diffuse Lighting Raw AOV. Add the result to the rest of the primary AOV composite stack. 

Reflection Fliter & Reflection Raw

Reflections Filter AOVReflections Raw AOV
The Reflections Filter AOV contains only the reflection color contents of a shader without any lighting contribution. The Reflections Filter AOV in conjunction with Reflections Raw AOV allows you to tweak the reflection results separately from each material's reflection color.

How to use:

Multiply the Reflections Filter AOV by the Reflections Lighting Raw AOV. Add the result to the rest of the primary AOV composite stack. 

Refractions Filter & Refractions Raw

Refractions Filter AOVRefractions Raw AOV
The Refractions Filter AOV contains only the refraction color contents of a shader without any lighting contribution. The Refractions Filter AOV in conjunction with Refractions Raw AOV allows you to tweak the reflection results separately from each material's reflection color.

How to use:

Multiply the Refractions Filter AOV by the Refractions Lighting Raw AOV. Add the result to the rest of the primary AOV composite stack. 

Caustics Raw

Caustics Raw AOV
The Caustics Raw AOV returns the result of caustic lighting separate from a materials diffuse color. 

How to use:

Multiply the Caustics Raw AOV by the Diffuse Filter AOV. Add the result to the rest of the primary AOV composite stack.

Translucency Filter, Translucency Lighting Raw & Translucency GI Raw

Translucency FilterTranslucency Lighting RawTranslucency GI Raw
In Redshift 'translucency' refers to diffuse lighting through the back-face of a surface – i.e. 'back-lighting'. It is a cheap, fake version of sub-surface scattering that is useful for very thin, but translucent, objects like paper or leaves. In order to complete the lighting equation in comp, Redshift offers three AOVs for translucency that become necessary when compositing with 'raw' lighting AOVs.

The Translucency Filter AOV contains only the flat translucency color component of the final shaded result. The Translucency Lighting Raw AOV contains only the diffuse translucency lighting component of the final shaded result. The Translucency GI Raw AOV contains only the translucency GI result of the final shaded result. 

How to use:

Add the Translucency Lighting Raw and the Translucency GI Raw together. Multiply the result by the Translucency Filter AOV. Add this result to the rest of the primary AOV composite stack. 

Compositing Raw AOVs

Nuke


A basic example of how to composite the raw shading component AOV's in Nuke

After Effects

A basic example of how to composite the raw shading component AOV's in After Effects


Flowchart for compositing raw shading component AOV's in After Effects

Fusion

A basic example of compositing the raw shading AOV's in Fusion

Utility AOVs

World Position AOV

World Position AOV
The world position AOV produces per-pixel XYZ world coordinates in the R, G, B channels respectively.

Due to effects like antialiasing, depth of field and motion blur, Redshift has to generate multiple samples per pixels ('subsamples'). The filter option allows the user to define how these sub-samples are combined to generate the final per-pixel world position. 

  • The 'full' filter option will average the world positions together for the pixel using the same filter used for unified sampling. 
  • The 'min depth' option returns the world position of the closest-to-the-camera pixel sub-sample. 
  • The 'max depth' returns the farthest-to-the-camera world position. 
  • The 'center sample' option picks the position that corresponds to the middle of the pixel using a single sample. 

Choosing these options depends on how you plan on using the world positions. If you need antialiased results, you should select 'full' filtering. If, on the other hand, you need non-antialiased results the 'center sample' option will provide the best results.

The world position AOV also has options to scale the X, Y, Z coordinates by user-defined factors. This can help convert them to other unit spaces (inches to meters, for example), if required.

The image above is an RGB representation of the world position AOV for the test scene. The origin is around the base of the drinking glass near the middle of the frame.

Object Position AOV

Object Position AOV

Puzzle Matte AOV

Puzzle Matte 1 AOVPuzzle Matte 1 Reflections / Refractions


Puzzle Matte 2 AOVPuzzle Matte 2 Reflections / Refractions
The Puzzle Matte AOV allows each of the R, G, B channels to contain the per-pixel contribution of a single object or material. Traditional objectID/materialID AOVs typically hold a single value per pixel which can produce aliasing-related issues when the same pixel can 'see' multiple objects/materials. This is especially true when the scene uses depth of field and motion blur. Additionally, having a single ID per pixel prevents the production of matte masks through reflections or refractions.

The Puzzle Matte AOV, on the other hand, holds per-pixel contributions of object/material IDs on separate RGB channels, which means the same pixel can 'mix' contributions from multiple (up to 3) objects/materials and be workable even in the presence of depth of field, motion blur and reflection/refraction.

In the examples above we have two different Puzzle Matte examples, Puzzle Matte 1 shows the lemons, drinking glass, and straw on their own respective color channels. Puzzle Matte 2 place the ice, underwater carbonation and surface carbonation bubbles on individual color channels. You can see that when reflections & refractions are disabled we can't see inside the glass at all, this is why the first Puzzle Matte 2 image is completely black, everything is behind the refractive glass in this Puzzle Matte.

Setting up a Puzzle Matte: 


Then, depending on whether the user decided to work with object IDs or material IDs, the appropriate mode for the puzzle matte AOV has to be set.

Then, each puzzle matte AOVs (there can be multiple puzzle matte AOVs) needs its Red/Green/Blue channels filled with the appropriate object/material IDs. Say we had three objects with object IDs 11, 21, 33 and we set the Red/Green/Blue channels to 11, 21, 33. This means that the Red channel will contain object ID 11, the Green channel will contain object ID 21 and the Blue channel will contain object ID 33.
If you have more than 3 objects/materials you want to create matte masks for, you can create multiple puzzle mattes and use different combinations of the IDs for red/green/blue.

The 'reflect/refract IDs' option defines whether the puzzle matte channels should also be filled using reflection/refractions. This allows the creation of object/material ID masks not only as seen from the camera but also as seen through reflections and refractions.

The following image shows how the puzzle matte looks like for our test scene. We assigned object IDs 1, 2, 3 to the yellow, cyan, magenta spheres respectively and made the puzzle matte red channel contain objectID 1, the green channel contains objectID 2 and the blue channel contains objectID 3. We enabled 'reflect/refract IDs' so that the puzzle matte also shows reflection/refraction coverage.