Shader for Mesh Segmentation

Hi folks, I am working on a project where I would like to get object segmentation masks using a shader. For example, imagine the two buses below are two models in a scene. We want to assign the same solid color to every pixel of one object, but different colors for different objects in the scene. I assume we can achieve this by changing the materials of these models to plain colors; however, this will affect the original RGB rendering. In our case, we would like to render the RGB image as well as its corresponding segmentation mask at the same time (by two different cameras with their corresponding shaders). Is there a solution for this scenario?



Thanks! I appreciate your helps!

 

Use a replacement shader.
https://docs.unity3d.com/Manual/SL-ShaderReplacement.html

 

More like
- make a script that put all objects of your scene into a list
- go through the list and assign a unique colors to each objects (color contrast base on list.count)
- render it to render texture
- save the texture

 

Will this affect rendering the original RGB images? The reason I want to use shaders instead of modifying objects is that I would like to have the RGB images and the segmentation masks side-by-side. Could you provide more details about how I can render both of them at the same time? Thanks!