What multi-pass channels are available?
To access Corona Renderer multi-pass channels, select the Corona item from the main menu, and then Multi-Pass... as shown below:
When you want to render just Geometry, Mask or some Shading passes, you can enable the "Render only masks (disable shading)" option:
Note: Don't forget to check the Enable box to use multi-pass rendering!
The following channels are available:
Basic
Note: Where relevant, these passes can have Denoising enabled independently for each pass.
Direct
All diffusely bounced direct illumination (light that bounced exactly once in the scene before hitting the camera).
Emission
All light that is emitted directly into the camera, with no bounces (e.g. directly visible lights sources, scene environment).
Indirect
All diffusely bounced indirect illumination (light that bounced at least twice in the scene before hitting the camera).
Reflect
All light specularly reflected into the camera (both direct and indirect). Includes imperfect and perfectly glossy (mirror) reflections.
Refract
All light that has passed through a surface with refraction (both direct and indirect). Includes imperfect ("frosted glass") and perfectly glossy refractions.
Translucency
All translucency lighting (both direct and indirect).
Volumetrics
It contains the scattering in volumetric media (useful for example for separating clouds and fog).
Geometry
NotmalsDotProduct
Outputs the angle between the surface normal and ray direction (similar to the Falloff map). White indicates the surface directly facing the view; surfaces facing away from the view (grazing angles) are black. This quickly shows how the scene looks without shading.
NormalsGeometry
Outputs the surface normal vectors as color values (with transformation RGB = (XYZ+[1,1,1])/2). Uses normals directly calculated from the geometry, with no bump mapping or smoothing groups.
NormalsShading
Outputs the surface normal vectors as color values (with transformation RGB = (XYZ+[1,1,1])/2). Uses the final shading normals from the lighting calculation, which include the effects of bump mapping and smoothing groups.
UvwCoords
Outputs the surface mapping coordinates for the selected channel. This can be used to check for mapping discontinuities and objects lacking mapping.
Velocity
Outputs a 32-bit image containing velocity information, which can be used to add motion blur in post-processing. It offers a choice between World and Camera mode, with adjustments for multiplier and offset - the mode and values you use will depend upon the expectations of your post-processing application, for example, Black Magic Fusion expects the defaults of Camera mode, Multiplier of 1, and Offset of 0.
WorldPosition
Outputs the surface world position XYZ vector directly as RGB color.
ZDepth
Outputs the z-buffer channel, with adjustable min (white) and max (black) depths.
Mask
ID
Assigns a random color to each pixel using one of the available modes. The most important ones are: Primitive ID: each primitive (typically triangle) in a mesh has a different color, Material ID: each assigned material ID has a different color, and Instance ID: each scene object has a different color.
Mask
Creates a custom set of rules for including/excluding each object from the mask. The available conditions are material gbuffer ID, object gbuffer ID, and direct object selections.
WireColor
Renders each object with a solid color based on the color used to display the wireframe in the Cinema 4D viewport (this is set using the Basic tab in the Attributes Manager for each object).
Shading
Albedo
Shows the albedo (total reflectivity of the surface - the fraction of energy that is reflected in any way from the surface) of the scene surfaces. Scenes with too high albedo can cause problems - a washed-out look and excessive render times. This pass can be used to quickly spot and fix problems - typically if your walls/floors/ceilings are shown in red, lowering their brightness will speed up rendering. Note: red does not automatically mean bad. The only problem is red on large, diffuse areas, like walls. For a more detailed guide, see: What is albedo? This pass will still render if "Render only masks" is checked.
Alpha
Duplicates the built-in alpha channel, so it can be saved to a separate location.
Bloom and Glare
Shows bloom and glare effects against a black background. See: how to use bloom and glare?
Components
This versatile render pass allows selecting a custom subset of lighting components. It can add diffuse, reflect, refract, and translucency lighting, in both direct and indirect (GI) variants. The basic decomposition passes can be recreated using this pass, or it can be used for finer division (e.g. separating reflect direct and indirect lighting). The components are shown below:
VirtualBeauty
Shows the beauty pass with independent bloom, glare, and denoising settings. Can be used to store both versions of the beauty pass - with/without denoising, with/without bloom and glare, without the need to re-save a separate file.
RawComponent
This shows one component (diffuse, reflect, refract, …) color divided by the corresponding CShading_SourceColor (input texture) value. This results in “raw” lighting, not containing the surface color/texture.
Shadows
Shows the shadows (energy subtracted from the image due to shadow ray occlusion). This is the complement to the beauty pass, showing white where there are black shadows. If this pass is linearly added to the beauty pass, it negates the visible shadows. Note that currently the shadows from environment lighting are always shown, resulting in a washed-out pass in typical interior renders.
SourceColor
The input color of a selected component (diffuse, reflect, refract, …). This is the value read from the texture, clamped to obey energy conservation laws. This pass will still render if "Render only masks" is checked.
LightMix
Full details on how to use LightMix can be found at How to use Interactive LightMix in Corona for C4D?
LightMix
This is the main LightMix element. It has to be added for LightMix to work. Bloom and glare can be toggled for this channel.
LightSelect
One LightSelect channel is required for each light that is to be controlled by the interactive LightMix. One or more lights can be included in one LightSelect channel.
Texmap
Allows evaluation of an arbitrary texmap on all scene surfaces/environment. For example, the AO pass can be easily created by adding CoronaAO texmap into this pass map slot.
See: how to use ambient occlusion?
Folder
Allows grouping channels into folders.
Saving Multipass Layers from the VFB & Picture Viewer
Saving Multipass layers is also possible with Corona for Cinema 4D. By default, this option is off and will need to be enabled from within the Corona Multipass window. This can be accessed from the main Corona dropdown menu in the Cinema 4D interface.
Once enabled, you can then drag in your desired passes into the "Active Passes" box.
(Enabled & Passes added)
This will then automatically enable more options in Cinema's main render settings under the "Save" tab.
(Multipass options visible in the render settings)
A save destination must be set and the output of the render must be in .PSD format. Once the image has been rendered, your output file can then be opened in Photoshop or other similar software that supports the .PSD format.
(Opened image in Photoshop with layers)
When working with Cinema's Picture Viewer, similar steps are also needed. Once the render has been completed, go to File > Save Image as. A pop-up window will be shown and you must enable "Layers" for this to work. Save your render and open it in Photoshop or similar.
(Saving from the Picture Viewer)