Beauty and Lighting Render AOVs
Version 2.0, Updated October 2024 using Octane 2024.1 and Cinema 4D 2025.0.2
About this Guide
This is the second guide in the Post Production/AOV series, and focuses on beauty and lighting Render AOVs, but doesn’t cover Output AOVs specifically. If that didn’t make sense, be sure to review the Intro to AOVs guide which covers the difference between the two AOV systems in Octane.
Note: This is version 2 of this guide and covers the recent changes made in Octane 2024. The masking passes (Render Layer and Cryptomatte) have been removed from this guide and will be covered in another guide in more depth.
A PDF version of this guide can be found here
Intro
This guide is more of a reference than anything else - it goes into detail about each lighting and beauty pass to explain what data they capture. While it touches on the info and data passes at the end, those are more advanced and will need their own guides to explore further (which is planned).
As a refresher, There are two different sets (stacks) of passes that - when combined in post - make up the final beauty render.
The first set is a stack of beauty passes, which refers to properties of all the materials in the scene like diffuse, reflection, refraction, etc. When all the appropriate beauty passes are combined with the Post Production pass, we end up with a final render (beauty pass).
The second set is a stack of lighting passes, which pulls data from all the various light sources and combines them with the Post Production pass to form the final beauty pass.
Which stack we choose depends on what we’re going to do with all the passes in post. In some workflows, we’ll want to adjust the color of objects or dial back/bring out certain attributes related to the materials and objects - for this, we’d generate beauty passes. In other cases the materials are all fine, but we might want to bring up or down lights in post to match other footage that we composite into the scene - for that we’d use a lighting pass stack.
Both of these stacks produce the same result, so if we were to combine all the beauty passes AND all the lighting passes, we’d end up with a blown out image. If we need control over both lights and materials the same composite, we have to do some work to figure out how to negate the effects of part of one stack before overlaying the second stack. There are a number of utility (info & masking) passes that are useful for this.
Beauty Passes
Beauty passes are based on the properties of the materials we have in our scene. When we merge all the passes that have some sort of contribution in post, we end up with the final beauty render.
The best way to start is to open up the Render AOV manager and at the Presets section at the top, make sure “Beauty surface” is chosen from the dropdown and click Load. This drops in all the most common ones: Diffuse, Emitters, Environment, Reflection, Refraction, SSS & Transmission. It doesn’t include volume AOVs or denoised passes. Denoised passes can be added en masse from the dropdown, and volume passes must be added individually.
If the pass is 100% black (no contribution), we can remove it so it doesn't add unnecessary time and data to the final file.
The Diffuse and Reflection passes can further be broken out into Direct and Indirect versions if we need that level of fine-tune control. This refers to whether we’re seeing the contribution of primary or secondary bounces controlled by the Diffuse/Specular/Scatter Depth controls in the render settings. Direct is the first bounce, Indirect is all the other bounces. We need to make sure that in our final stack, we either have the direct+indirect passes, OR we have the combined pass. If we have both, we’ll effectively double the contribution and it’ll likely look blown out or just wrong.
If we’re using the Render AOV system, we can get a denoised version of direct and indirect diffuse and reflection, volume, volume emission passes, and then a denoised remainder which merges refraction, transmission, and subsurface. There are ways to further break these out when using Output AOVs which we’ll look at in another guide.
There are also filter passes for some of the properties. These are more like info passes and don’t contribute to the beauty render, but do show us the color and intensity of the property mostly for troubleshooting purposes (ohh, THAT’s why the reflections are red, etc.)
Diffuse Passes
The diffuse pass contains the data from the color/albedo/diffuse channel of all the materials.
In the above illustration, the ice cream is made from a material with both diffuse and specular properties. The cone is mostly diffuse, but has some sheen, as well as criss-crossed lines with metallic and emissive properties. The backdrop is metallic. The diffuse pass only isolates the diffuse properties of the ice cream and the cone itself. The metallic and emissive materials in this scene have no albedo/color/diffuse contribution, so they show up black in the Diffuse pass. The post processing effects (just bloom in this case) don’t show on the diffuse passes either - they’re on their own pass.
Diffuse can also be split into Direct and Indirect passes. If we want to preserve the original intention of the render, we should either pick direct+indirect, or just the diffuse pass, but not all three combined.
The Diffuse Filter pass only shows the color of the diffuse materials (no shading). It’s a utility pass, so it doesn’t factor into the normal beauty pass stack - it’s mostly there for troubleshooting, but could be used creatively for non-photoreal renders or effects.
Reflection Passes
This is the same scene as the previous one, but now we’re just seeing the reflection contribution of the materials. There’s some sheen in the cone and subtle coloring from the coating layer in the ice cream which we can actually best see in the reflection filter. It’s also giving us the contribution from the metallic channel in the backdrop and some of the lines in the cone, and the specular properties of the ice cream.
Reflection passes are similar to Diffuse where there’s a Direct & Indirect version that we can combine to get the standard Reflection Pass. Again, we’d either choose to use the direct/indirect passes separately, or the combined Reflection pass, but not both. There’s also a reflection filter pass for troubleshooting or other creative effects.
Refraction & Transmission Passes
The Refraction and Transmission passes pick up the effects of the Transmission channel in a material. If the Transmission Type is set to Specular or Thin Wall, it will appear on the Refraction pass. If it’s set to Diffuse or Thin Wall (Diffuse), it will show up in the Transmission pass. Refraction also shows the effects of the Absorption medium.
The filter passes show the color of the transmission. It’s pretty obvious in Diffuse, but in the Specular type material (the cone), the filter shows 100% white because that’s the color of the transmission property (in this case the float = 1 which is the same as 100% white).
Important: The refraction AOV is always an opaque image of whatever is being distorted by the IOR of the refractive material (glass, etc.). Refraction in Octane is physically accurate and relies on the scene being 3D (which it no longer is after it’s been rendered). This is one of those weird concepts that makes perfect sense as soon as we realize why, but up until then is baffling and frustrating. There are advanced workarounds and ways to fake this in post if needed, but that’s out of the scope of this guide.
Subsurface Scattering Pass
This just shows the Subsurface scattering portions of materials with Scattering or Random Walk mediums applied. It does not show the Absorption medium (that goes in Refraction). There’s no filter pass for SSS, and if we’re using the denoiser, SSS shows up in the Denoised Remainder pass instead of its own unique denoised SSS pass.
This just contains the scattering in the materials - scattering in volume mediums like VDBs or volumetric spotlights appear in the Volume passes (covered later in this guide). The new fog post effect shows up in the Post Processing pass along with bloom, glare, post-based CA, and all that other fun stuff.
Emitters Pass
The Emitters pass shows the direct contribution of the Emission channel of the materials that have it. The emitters pass renders out similar to a filter pass - it only shows the color and power of the emission on the material - it doesn’t also provide glow or secondary light.
If the emitter is obstructed by a transmissive material, the obscured portions will appear in the refraction or transmission pass instead of the emitters pass. If we want the effects of the emitter, we’ll need to render lighting passes (next section). Bloom/Glare is found in the post processing pass.
Environment Pass
HDRI: Zwartkops Start Morning by Poly Haven
If we have a scene where the HDRI and/or Octane Sun & Sky Rig is visible in the background, the Environment AOV is where it will go.
Important: The entire environment renders on this pass, not taking into account any of the objects in the scene. If we try to add the environment to the rest of the beauty layers, we’d end up with the overlapping portion containing data from both the environment and the other beauty layers. This causes our objects to look blown out and ghosted like we see in the fourth panel above.
A good way around this is to render a mask for all the foreground objects by using Render Layer or Cryptomatte and then use that mask to knock out the section of the Environment AOV that the foreground objects overlap.
The masking technique doesn’t affect reflected or refracted portions of the environment - they will still show up in the Reflections and Refractions passes.
Beauty-Volume
Volume passes are in a separate bucket than Beauty-Surface passes. We need to add these into the mix if we have volumes in our scene. This includes things like VDBs and volumetric spots, not SSS in materials which is found in the Subsurface Scattering pass, or post-based fog which shows up in the Post Processing pass.
The two main ones are Volume and Volume Emission, but there are also special AOVs just for getting the z-depth of volumes or masking.
In some cases, masking the volume passes (or the rest of the passes) is needed to get the layers to look right when combined.
Post Processing
This is for bloom, glare, CA, lens flare, and post fog if we’ve enabled them in our Imager settings. The original Post Processing pass was only meant as an overlay on top of a beauty stack and does not take alpha into consideration (so we couldn’t have a transparent PNG with a glow, for instance). We also can’t break the effects out individually (so no pass with just bloom or just glare).
The newer post passes in Octane 2024 are far more versatile, and we’ll look at those in another guide.
Reconstructing Beauty Passes
Once we’ve rendered out every beauty pass that contributes to our scene, all of these passes will be combined using the Linear Dodge (Add) blend mode in our post processing comp. If they all go over a black background (or we leave the bottom-most layer at the Normal blend mode), it should look exactly the same as what we see in the flattened beauty pass in the Live Viewer.
Lighting Passes
Lighting passes break the lighting in the scene up so that we have control over the intensity of individual lights in post.
A stack of AOVs that includes all of the various light contributions (sunlight, environmental light, emissive materials and physical lights like the area light) is a complete stack, meaning there’s no need to also use Diffuse, Reflection, or any of the other beauty passes. When combined, all of the lighting AOVs will form the final beauty render on their own.
Lighting Pass Types
There are only three types of light passes: Light, Light Direct, and Light Indirect. Similar to some of the beauty passes, a Light Pass is the same as Light Direct + Light Indirect.
Usually we will want to either use the simplified Light pass, or get more granular control by combining a Direct and Indirect Light Pass for each Light Group. If we render out all three and combine them, the light intensity will be 2x brighter than the original beauty render.
For physical lights (area lights and such), we can specify a Light Pass ID on each to group them together (by putting multiple lights on the same ID) or separate them all out (by putting each light on its own ID). The Light Pass ID is located in the Octane Light tag that comes standard with an Octane light (see image above). Emissive materials can also be assigned to different Pass IDs in the Blackbody or Texture Emission Shaders. Every object with that material goes on the same light pass, so if we need to separate out different emissive objects by Light ID, we’ll need unique materials on each.
After we add a Light, Light Direct, or Light Indirect AOV, there’s an option to choose which Light ID we want this pass to cover. We need to make sure we add enough of these AOVs to cover all the Light IDs we assigned to our various lights, plus a Sunlight AOV if we have a Daylight or Planetary rig, and Environment for HDRI lighting if we’re using that.
Environmental light (anything generated by an Octane Environment object) is automatically placed in the Ambient lighting pass. Anything generated by an Octane Daylight Rig automatically goes on the Sun pass. Emissive materials and area lights show up on the passes they were assigned to.
If we’re using a light with a medium in it (like an Octane Spotlight), and assign that to its own Light Pass ID, the effects of the medium from that light (not the emission from the light) will appear in all lighting passes. Just something to be aware of if we’re using spots or adding scattering into our lights.
Reassembling Lighting Passes
Similar to Beauty passes, a simple lighting pass composite is pretty easy. We need to make sure we have passes enabled for every light or material we want on a different layer (Environment, Sun, every Light Pass ID we’ve used).
Once all the passes are rendered, they’re combined in a post application using the Linear Dodge (Add) blend mode. Order doesn’t matter, but usually we’ll want the post processing AOV at the top to make it easy to find. We either want to have the bottom-most layer be solid black or a lighting pass set to the Normal blend mode.
All lighting passes + the Post Processing pass (bloom & glare) should give the same result as the compiled beauty pass we see in the Live Viewer.
Info, Data, and Utility Passes
These are extra passes that are useful for compositing or troubleshooting.
Masking AOVs
Octane has two ways to mask out objects in the scene so they can be worked on separately in post: Cryptomatte and Render Layer. There will be an entire guide on this since it’s a bit complicated.
ID & Info AOVs
IDs: Baking group ID | Light pass ID | Material ID | Object ID | Object Layer Color | Render Layer ID
Material properties: Filters (Diffuse, Reflection, Refraction, Transmission) | IOR | Opacity | Roughness
Model properties: Wireframe
Render properties: Noise
These are primarily for visualizing different group assignments by color or shades of gray so we can troubleshoot other issues in the scene. For example, it may help us find the one light post we forgot to include on a certain layer, or maybe a material has a crazy high IOR that’s causing weirdness with refraction. Wireframe is good for checking the geometry of the models at a glance to see if there are any problem areas or if one particular model has a ridiculous amount of geometry that’s causing VRAM issues. The Noise pass shows up when we use Adaptive Sampling, and is also just handy to see what areas of the render are particular brutal on our GPUs.
Light Effect AOVs
Ambient Occlusion | Irradiance | Shadow
These AOVs produce the effects of the global lights and shadows in the scene on the models. These effects are already taken into account in a full lighting or beauty stack, so they’re not strictly needed, they’re just there to get a particular look or style in post by quickly boosting the overall irradiance (global illumination) or shaded areas in post.
Data AOVs
Light direction | Motion vector | Normal (geometric/shading/smooth) | Position | Texture tangent | UV coordinates | Z-depth
These passes can be used in advanced compositing techniques to control effects like motion blur, depth of field, re-lighting a scene, or tracking and affecting other added objects in the composition.
Custom / Global Texture AOVs
These AOVs can be customized to produce specific effects. We’ll look at these in future guides.
Wrap Up
That’s it for the passes. At this point, you should have a good idea of what the two complete stacks (beauty and lighting) do, how they’re broken up, and what properties are rendered on which passes. You should also now be aware of all the utility and info passes and generally what they’re used for.
We’ll explore more specific workflows and techniques in future guides, so stay tuned.