Octane for 3dsmax

The Dirt texture creates different effects based on ambient occlusion calculations. This texture always returns a random value and can simulate dirt, dust, or wear and tear. This texture is often plugged into the Diffuse, Bump, or Transmission parameters.

Figure 1: Dirt parameters 

Figure 2 illustrates the Dirt texture with differing Strength, Details, Radius, and Invert settings. 

Figure 2

Dirt Texture Parameters

Strength - Controls the Dirt intensity across the geometry surface.

Details - Controls the Details intensity.

Radius - Controls the dirt spread across the model's surface from the recessed parts towards the exposed parts.

Radius Map - Determines the proportion of the maximum area affected by the dirt texture.

Tolerance - Reduces black edges on rough tessellated meshes.

Spread - Controls the ray direction with respect to the normal of the surface. A value of 0 means the dirt direction is shot in the direction of the surface normal and a value of 1 shoots the dirt rays in all directions.

Distribution - Forces the rays to gather closer to the surface normal. A value of 1 is the equivalent to ambient occlusion on a diffuse surface. A value of 0 gathers the rays in the normal direction.

Bias - Any non-zero bias will be used as the shading normal to sample the dirt rays.

Bias Coordinate Space - Determines the coordinate space for the bias vector.

Include Object Mode - By default the mode is set to All, which considers all object intersections in the dirt calculation. If Self is selected, then only the ray-intersection with other objects is used for the dirt calculation.

Invert Normal - Reverses the Dirt texture effect based on the normal surface direction.