VRayDirt Overview

The VRayDirt is a texture map that can be used to simulate a variety of effects, for example dirt around the crevices of an object, or to produce an ambient occlusion pass.

VRayDirt Parameters

White  - this is the color that will be returned by the texture for unoccluded areas. You can also use a texture map for this parameter.

Black  - this is the color that will be returned by the texture for occluded areas. You can also use a texture map for this parameter.



Glossiness  - this parameter controls the spread of the rays traced for reflection occlusion. You can also use a texture map for this parameter.

Mode  - Allows you to specify the procedural mode that will be used to generate the VRayDirt texture.

  • 0  - Ambient occlusion
  • 1  - Phong reflection occlusion
  • 2  - Blinn reflection occlusion
  • 3  - Ward reflection occlusion

Bias (X,Y,Z) - these parameters will bias the normals to the X (Y,Z) axes, so that the dirt effect is forced to those directions. Consider that these parameter can also take negative values for inverting the direction of the effect.

Example: Bias

These parameters will bias the normals so that the dirt effect is forced to some of the axis(es).

bias_X: 100.0

bias_Y: 100.0

bias_Z: 100.0

Radius  - this parameters determines the amount of area (in scene units) where the VRayDirt effect is produced. You can also use a texture to control the radius. The texture intensity is multiplied by the radius to calculate the final radius at a given surface point. If the texture is white at a given surface point, the full radius value is used. If the texture is black, a radius of 0.0 is used.

Falloff  - this parameter controls the speed of the transition between occluded and unoccluded areas.

Example: Falloff Parameter

falloff: 0.0

falloff: 1.0

falloff: 5.0

Subdivs  - controls the number of samples that V-Ray takes to calculate the dirt effect. Lower values render faster but produce a more noisy result.


Example: Subdivs Parameter 

subdivisions: 1

subdivisions: 5

subdivisions: 20

Double-Sided  - when enabled the rays needed to generate the dirt map will be shot from both sides of the faces (both in the direction of the normals and in the opposite direction).

Ignore for GI  - this check-box determines whether the dirt effect will be taken into consideration for GI calculations or not.


Example: Ignore for GI

This check-box determines whether the dirt effect is going to be visible during the GI calculation.

ignore for GI: on

ignore for GI: off

Example: Consider Same Object Only

consider same object only: on

Ignore Self Occlusion  - when this option is on the object will not occlude itself. It will still be occluded by other objects in the scene.

Ignore other objects  - when on, the dirt will affect only the objects themselves, without including contact surfaces and edges. If off, the entire scene geometry is participating for the final result. 

Use Transparency  - when onVRayDirt will take into account the opacity of the occluding objects. This can be used, for example, if you want to calculate ambient occlusion from opacity-mapped trees etc. When off (the default), occluding objects are always assumed to be opaque. Note that working with correct opacity is slower, since in that case VRayDirt must examine and evaluate the material on the occluding objects. 

Invert normal  - this option allows to revert the effect with respect to surface normals - e.g. instead of crevices, open corners will be shaded with the occluded color.

Example: Invert Normal

In the next example, a bitmap is used in the texmap radius slot. Notice that the main radius parameter still has effect - it determines the amount of area where the texmap radius bitmap would blend.

invert normal: off

invert normal: on

Environment occlusion  - when this option is checked V-Ray will use the environment when calculating the occlusion of areas that are not occluded by other objects. 

Affect Reflection  - when checked the ambient reflection will affect the reflection render elements. This can be used to create reflection masks.