Image Description: We start by adding a custom color as a render pass, and assign it to the active render layer.

Image Description: Open the Hypershade and create multiple “writeToColorBuffer” nodes that match the same number of shaders you have in the scene.

Image Description: In the Hypershade, middle-mouse drag the shader on top of the writeToColorBuffer node and choose “Evaluation Pass Through”. Repeat the above step for each shading network such each element in the scene "contributes" to the custom color frame buffer. This approach can also be done on "per face" shading network, where we can use colorCustom Pass to extract a particular set of faces to ease selection and masking.

Image Description: In the Attribute Editor for each of the writeToColorBuffer nodes, choose "customColor" as the Custom Color Pass. For each material give a unique color value thus making the material different even if they share the same color value or have a texture assigned to them.

Image Description: This is the result of a material ID pass using custom color pass.Obnj

Image Description: This will add a new attribute (called “MI Label”) for all the objects in the Extra Attributes section.

Image Description: Select the render camera and under the mental ray section > Output Shaders, select the Create button. This will create a mentalrayOutputPass.

Image Description: Change the Frame Buffer Type to “Label (Integer) 1x32 Bit”. Note: you can change the image format and the name of the pass according to your needs. It would be important to provide a File Name Postfix (suffix) to ensure proper naming of rendered elements on disk.

Image Description: The result will be a separate rendered file in the format selected in the Image Format field. in this case we use imf_disp to view the file, since it will automatically color each labels to better visualize the result.

Image Description: Beauty Render

Image Description: We will start by adding a “Custom Depth” pass in our associated passes, and then associate this pass to the active render layer

Image Description: In the Hypershade, we will add multiple “writeToDepthBuffer” nodes. These nodes can be found under the Miscellaneous section of the mental ray nodes.

Image Description: We will connect the “.outColor” attribute of the Shader to the writeToDepthBuffer’s “.evaluationPassThrough” attribute.

Image Description: In the Attribute Editor of the writeToDepthBuffer, change Custom Depth Pass to the custom depth pass node that we added in the Render Settings. For each writeToDepthBuffer node we will give a different value for each Depth.

Image Description: Once we render the result will be like this. Each depth value can be considered as "ID" in this case. It is important to use a file format that can support HDR, like IFF and openEXR.

Image Description: In this example, this geometry has multiple UV shells (11 in total) and all located in the 0-1 region.

Image Description: We will start by creating a Custom Color Pass (same as above) and then assign it to the active render layer.

Image Description: Then add a “writeToColorBuffer” node in the Hypershade

Image Description: In the Hypershade, middle-mouse drag the shader on top of the writeToColorBuffer node and choose “Evaluation Pass Through”. Again, in Hypershade, under the mental ray Nodes > Textures section, create a mib_texture_vector node. Then add it to the Color value of the writeToColorBuffer node.

Image Description: In the Attriubte Editor for each of the writeToColor nodes, choose “Custom Color” as our Custom Color Pass. For the Color input, it will be driven by another shader which "extract" UVs

Image Description: In the mib_texture_vector node, change the “Project” to “uv”. By default the shader will extract the first UV (0), if you have many UVs, you need to increase the "select" attribute to 1, or 2, etc.

Image Description: Now when you perform a render, you will get a color variation based on the UV shells of your mesh.