Passes¶

Passes can be used to split rendered images into colors, direct and indirect light to edit them individually, and also to extract data such as depth or normals.

Cycles¶

Reference

Panel: Scene ‣ View Layers ‣ Passes

Passes can be used to split rendered images into colors, direct and indirect light to edit them individually, and also to extract data such as depth or normals.

Data¶

Z: Distance to any visible surfaces.

Note

The Z pass only uses one sample. When depth values need to be blended in case of motion blur or Depth of Field, use the mist pass.
Mist: Distance to visible surfaces, mapped to the 0.0 - 1.0 range. When enabled, settings are in World tab. This pass can be used in compositing to fade out objects that are farther away.
Normal: Surface normal used for shading.
Vector: Motion vectors for the Vector Blur node. The four components consist of 2D vectors giving the motion towards the next and previous frame position in pixel space.
UV: Mapped UV coordinates, used to represent where on a mesh a texture gets mapped too. This is represented through the red and green channels of the image. The blue channel is encoded with a constant value of 1 but does not hold any information.
Object Index: Creates a mask of the object that can be later read by the ID Mask Node in the Compositor.
Material Index: Creates a mask of the material that can be later read by the ID Mask Node in the Compositor.
Denoising Data: Passes needed by the denoiser, for performing animation denoising in a second pass after rendering the entire animation. For still image denoising as part of the render process these are not needed.
Render Time: Render time in milliseconds per sample and pixel.
Sample Count: Number of samples/camera rays per pixel.

Note

The Z, Object Index and Material Index passes are not anti-aliased.

Alpha Threshold: Z, Index, normal, UV and vector passes are only affected by surfaces with alpha transparency equal to or higher than this threshold. With value 0.0 the first surface hit will always write to these passes, regardless of transparency. With higher values surfaces that are mostly transparent can be skipped until an opaque surface is encountered.

Light¶

Combined: The final combination of render passes with everything included.
Noisy Image: If denoising is enabled, the original combined pass before denoising.
Diffuse Direct: Direct lighting from diffuse and subsurface BSDFs. We define direct lighting as coming from lights, emitting surfaces, the background, or ambient occlusion after a single reflection or transmission off a surface. BSDF color is not included in this pass.
Diffuse Indirect: Indirect lighting from diffuse and subsurface BSDFs. We define indirect lighting as coming from lights, emitting surfaces or the background after more than one reflection or transmission off a surface. BSDF color is not included in this pass.
Diffuse Color: Color weights of diffuse and subsurface BSDFs. These weights are the color input socket for BSDF nodes, modified by any Mix and Add Shader nodes.
Glossy Direct, Indirect, Color: Same as above, but for glossy BSDFs.
Transmission Direct, Indirect, Color: Same as above, but for transmission BSDFs.
Emission: Emission from directly visible surfaces.
Environment: Emission from the directly visible background. When the film is set to transparent, this can be used to get the environment color and composite it back in.
Shadow: Shadows from light objects. Mostly useful for compositing objects with shadows into existing footage.
Ambient Occlusion: Ambient occlusion from directly visible surfaces. BSDF color or AO factor is not included; i.e. it gives a ‘normalized’ value between 0 and 1.

Note

Transparent BSDFs are given special treatment. A fully transparent surface is treated as if there is no surface there at all; a partially transparent surface is treated as if only part of the light rays can pass through. This means it is not included in the Transmission passes; for that a glass BSDF with index of refraction 1.0 can be used.

Combining¶

All these lighting passes can be combined to produce the final image as follows:

../../_images/render_layers_passes_combine.svg

Cryptomatte¶

Cryptomatte is a standard to efficiently create mattes for compositing. Cycles outputs the required render passes, which can then be used in the Blender Compositor or another compositor with Cryptomatte support to create masks for specified objects.

Unlike the Material and Object Index passes, the objects to isolate are selected in compositing, and mattes will be anti-aliased and take into account effects like motion blur and transparency.

Object: Render cryptomatte object pass, for isolating objects in compositing.
Material: Render cryptomatte material pass, for isolating materials in compositing.
Asset: Render cryptomatte asset pass, for isolating groups of objects with the same parent in compositing.
Levels: Sets how many unique objects can be distinguished per pixel.
Accurate Mode: Generate a more accurate Cryptomatte pass. CPU only, may render slower and use more memory.

Typical Workflow¶

Enable Cryptomatte Object render pass in the Passes panel, and render.
In the compositing nodes, create a Cryptomatte node and link the Render Layer matching Image and Cryptomatte passes to it.
Attach a Viewer node to the Pick output of the Cryptomatte node.
Use the Cryptomatte Add/Remove button to sample objects in the Pick Viewer node.
Use the Matte output of the Cryptomatte node to get the alpha mask.

Shader AOV¶

Shader AOVs (Arbitrary Output Variables) provide custom render passes for arbitrary shader node components. As an artist this can be a good way to debug or tweak very fine details of a scene in post processing. To use Shader AOVs create the pass in the Shader AOV panel then reference this pass with the AOV Output shading node. Shader AOVs can be added or removed in the Shader AOV panel. In this panel is a list of all AOV passes; each AOV in the list consists of a Name and Data Type.

Name: The name of the render pass; this is the Name that is referenced in the AOV Output node. Arbitrary names can be used for these passes, as long as they do not conflict with built-in passes that are enabled.
Data Type: Shader AOVs can either express a Color or a Value variable. The Color variable as the name suggest can be used for a color but also a normal value. A Value variable can be used for any single numerical value.

Eevee¶

Reference

Panel: Scene ‣ View Layers ‣ Passes

Passes can be used to split rendered images into colors and light to edit them individually, and also to extract data such as depth or normals.

Lighting Passes¶

Combined: The final combination of render passes with everything included.
Diffuse Light: Direct lighting from diffuse BSDFs. We define lighting as coming from lights, the background, or ambient occlusion off a surface. BSDF color is not included in this pass.
Diffuse Color: Color weights of diffuse BSDFs. These weights are the color input socket for BSDF nodes, modified by any Mix and Add Shader nodes.
Specular Light, Color: Same as above, but for specular BSDFs.
Emission: Emission from directly visible surfaces.
Environment: Emission from the directly visible background. When the film is set to transparent, this can be used to get the environment color and composite it back in.
Shadow: Shadows from light objects. Mostly useful for compositing objects with shadow into existing footage.
Ambient Occlusion: Ambient occlusion from directly visible surfaces. BSDF color or AO factor is not included; i.e. it gives a ‘normalized’ value between 0 and 1.
Volume Transmittance: The transmittance pass from volume objects or world.
Volume Scattering: The scattering pass from volume objects or world.

Data Passes¶

Z: Distance to any visible surfaces.
Mist: Distance to visible surfaces, mapped to the 0.0 - 1.0 range.
Normal: Surface normal used for shading.

Effect Passes¶

Bloom: The influence of the Bloom effect.

Combining¶

The passes can be combined to produce the final image as follows:

../../_images/render_layers_passes_eevee-combine.svg

Note

Limitations:

Alpha blended materials are not rendered in render passes except the combined pass. Use the Alpha Clip or Alpha Hashed as Blending Mode to render transparent materials in render passes.
Depth of field is not rendered in render passes except the combined pass. It is possible to add the depth of field back in the Compositor using the Defocus node.