Can be used with the Gradient Texture Node. The Instance Range texture holds a gradient color with the range of 0 - Maximum ID, and prepares this range to map to geometric instance IDs. This node has one attribute, Maximum ID, which corresponds to the total number of instanced geometry in the scene for which the MaterialThe representation of the surface or volume properties of an object. is applied.
Figure 1: The Instance Range texture maps a Gradient onto a series of instanced cubes
You should set the Instance Range texture's Maximum ID parameter to the corresponding number of instances its Material is applied to in a scene.
Figure 2: The Maximum ID value set to a corresponding number of instances in a scene
Object instance IDs are set in an Object's Octane Properties window, which you can find in the Quad menu when right-clicking on an Object.
Figure 3: Specifying Instance IDs from the Octane Object Properties window