How to use the Corona Cryptomatte - C4D

What is the Corona Cryptomatte?


The Corona Cryptomatte is a render pass that will help you easily create color mattes of a complex scene with hundreds of objects.

It uses three methods to automatically generate the render channels stored in a multichannel OpenEXR file which removes the hassle of creating dozens or hundreds of single masking elements.

To extract the mattes from still images you need to use specialized software. One example is the free Exr-IO plugin for Photoshop (you can download it here). Without the plugin, Photoshop won't be able to extract the Cryptomatte data correctly.

Currently, to use the Cryptomatte element properly, you must save the element in the .CXR file format from the Corona VFB, rename it to change its extension to .EXR and then load it in your preferred compositing software.

 

CM_Render.jpg

Example of the "Beauty" render image.

 

01_Cryptomatte_Cover_Cryptomatte.jpg

This is what the Cryptomatte pass looks like when rendered.

Note: what you see in the VFB is just a preview. It is not an accurate representation of the data included in the Cryptomatte element. Some visual artifacts may appear (e.g. when using motion blur and DOF), and the colors may not appear to be distributed correctly, but this does not affect the usability of the element in post-production. 

 

 

How to use the Corona Cryptomatte?


To start using the Corona Cryptomatte, simply go through the following steps: 

  • Open the Corona Multi-pass window. You can find it in the menu Corona > Multi-pass...

multi1.jpg

  • Then make sure to enable the active passes by activating the "Enbl" checkbox.

03_Cryptomatte_Enable_Multi-pass_UI.png

  • Next, from the "Available passes" section on the left, open the category "Mask", and drag the Cryptomatte pass and drop it into the "Active passes" section in the middle.
    (alternatively, you can use the little right arrow button located between the sections mentioned above to add the Cryptomatte pass)

04_Cryptomatte_Add_Pass_UI.png



 

The Corona Cryptomatte parameters


You can adjust the Cryptomatte's behavior by modifying its parameters.

05_Cryptomatte_Parameters_UI.png

 

The ID type

This parameter determines how many objects are distinguished in the Cryptomatte pass.

You can set it to work using any of the three available modes.

 

ID type: Name

Using this mode, only objects with the same name will have the same color. This means that if all of your scene objects have different names, different colors will be assigned to each one of them.

06_Cryptomatte_IDtype_Name.png 08_Cryptomatte_IDtype_Name_Example_ObjectMan.png
In this example, the ID type is set to "Name" In this example, each object has a different name.

 

07_Cryptomatte_IDtype_Name_Example.png

This is the resulting Cryptomatte pass when the ID type is set to "Name"

 

 

ID type: Name with hierarchy

Using this mode, only objects with the same name and in the same group hierarchy in the object manager will have the same color. 

09_Cryptomatte_IDtype_NameWithHierarchy.png 11_Cryptomatte_IDtype_NameWithHierarchy_Example_ObjectMan.png
In this example, the ID type is set to "Name with hierarchy" In this example, objects in the same group have the same name.

 

10_Cryptomatte_IDtype_NameWithHierarchy_Example.png

This is the resulting Cryptomatte pass when the ID type is set to "Name with hierarchy"

 

 

ID type: Layer

Using this mode, only objects in the same layer will have the same color.

12_Cryptomatte_IDtype_Layer.png 14_Cryptomatte_IDtype_Layer_Example_LayerMan.png
In this example, the Id type is set to "Layer" In this example, the objects have been assigned to different layers.

 

13_Cryptomatte_IDtype_Layer_Example.png

This is the resulting Cryptomatte pass when the ID type is set to "Layer"

 

ID type: Material

Using this mode, only objects with the same material will have the same color. This means that if all of your scene objects have different materials, different colors will be assigned to each one of them.

 

Corona _12_CryptoMatte_Cinema_4D.png

In this example, the Id type is set to "Material"

 

Corona 12_Interior CryptoMatte_Cinema 4D.jpg

This is the resulting Cryptomatte pass when the ID type is set to "Material"

 

Maximum object levels

This parameter determines how many different objects can be identified by the Cryptomatte in a single pixel. By default, this value is set to 6.

 

 

Notes:

  1. What you see in the VFB is just a preview. It is not an accurate representation of the data included in the Cryptomatte element. Some visual artifacts may appear (e.g. when using motion blur and DOF), and the colors may not appear to be distributed correctly, but this does not affect the usability of the element in post-production. 

  2. Currently, to use the Cryptomatte element properly, you must save the element in the .CXR file format from the Corona VFB, rename it to change its extension to .EXR and then load it in your preferred compositing software.

 

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