Particle Render Outputs

This topic describes the different Particle render outputs.

Particle Age

The Particle Age output assigns a gray-shaded value to each particle based on its age (in seconds), starting at black and moving toward white. Values are stored as floating point numbers, so an extended dynamic range format is necessary to save this output.

Particle ID

The Particle ID output assigns a random floating point ID number to each particle, which is represented by a gray shade from 0 to 1, black to white. Values are stored as floating point numbers, so an extended dynamic range format is necessary to save this output.

Particle Velocity

The Particle Velocity encodes the velocity value to a floating point number, representative of the speed the particle is traveling at the current frame. The floating point values are represented as a color in the image that extends beyond the common range of color values, so an extended dynamic range format is necessary to save this output.

Compositing Outputs

Render outputs are incredibly useful when you wish to compose the generated layers individually in an external application, such as Photoshop, After Effects, Nuke or Fusion. This can aid in tweaking color, among other settings as a post process without requiring additional render time. The question most often asked is which render outputs combine to equal the final color output. The answer is Diffuse Shading (Total) + Transparent Shading + Reflection Shading + Specular Shading + Subsurface Shading + Luminous Shading = Final Color, where each successive layer is added to the layer below in the composition (also called linear dodge). Rendering each layer at a gamma of 1.0 and then combining them and adding the gamma back to the fully composed layers produce the best results.

You may also render out simultaneous alpha channels for each item in a scene by creating item masks for each and placing a render output set to Effect > Alpha (or simply adding them to existing Shader Tree masks). Then each time a render command is invoked, all active render outputs get generated simultaneously.