The diffuse layer is basically the color of an object, although it final color is a composite of many material aspects of course.

Again the diffuse layer can have a transparency mask, we have 2 diffuse layers. You can use the transparency to make mixes of both diffuse layers (handy for fast mixing textures) or you can make the diffuse both just a slight effect, like a dirty glass p.e. in the screenshot below you see the white dots in transparency that lets looks through the yellow diffuse below, also in combination with translucency, it often makes sense to keep a certain amount of diffuse to achieve a semi opak body.

Diffuse Color

Color – this is the diffuse color of the material. Note the actual diffuse color of the surface also depends on the reflection and refraction colors.

Brightness – use this setting to adjust the brightness of a channel’s color.

Texture – here an image texture or shader can be defined.

Mix Mode – use these parameters to mix the color and texture panes using one of four modes. The default mode for all channels is Normal. If you load a texture or shader, it is placed on a layer above the color (i.e. the texture is placed on top of the color). Please consult the Cinema4d documentation about the different mix modes.

Mix Strength – defines the mixing proportion between the texture and color.

Diffuse Layer Transparency

Color – this is the transparency color of the material.

Amount – use this setting to adjust the transparency of a channel. use this setting to adjust the transparency of a channel. use this setting to adjust the transparency of a channel.

Texture – here an image texture or shader can be defined.

Mix Mode – use these parameters to mix the color and texture panes using one of four modes. The default mode for all channels is Normal. If you load a texture or shader, it is placed on a layer above the color (i.e. the texture is placed on top of the color). Please consult the Cinema4d documentation about the different mix modes.

Mix Strength – defines the mixing proportion between the texture and color.

Invert – This option simply inverts the Texture Map, so transparent and solid areas are reversed. This works for both clipped images and images with built-in alpha channels.

Diffuse Options

Roughness – this parameter controls the surface roughness for the material. A value of 0.0 produces a diffuse material, while higher values give the surface a translucent quality.

Texture – here an image texture or shader can be defined.

Use Irradiance map – when this option is on, the irradiance map will be used to approximate diffuse indirect illumination for the material. If this is off, brute force GI will be used. You can use this for objects in the scene which have small details and are not approximated very well by the irradiance map.

Use VrayDirt – This option turn on VrayDirt.

2nd with Inverted Normals – This option inverts normals of VrayDirt with specific parameter that set in VrayDirt mixing.

VrayDirt mixing – use these parameters to mix VrayDirt.

V-Ray Dirt

Radius – this parameters determines the amount of area (in scene units) where the VRayDirt effect is produced.

Texture – this texture map control the radius area. 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.

Occluded color – this is the color that will be returned by the texture for occluded areas. You can use a texture map or Cinema4D shader for this parameter.

Unoccluded color – this is the color that will be returned by the texture for unoccluded areas. You can use a texture map or Cinema4D shader for this parameter.

Distribution – this parameter will force the rays to gather closer to the surface normal. The effect is that the dirt area is being narrowed closer to the contact edges. For ambient occlusion, set this parameter to 1.0 to get distribution similar to the ambient lighting on a diffuse surface.

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

Subdivision – controls the number of samples that takes to calculate the dirt effect. Lower values render faster but produce a more noisy result.

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 inversing the direction of the effect.

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

Consider same Obj only – 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.

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.

Work with transparency – when on, VRayDirt 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.

Ignore Self Occlusion – allow dirt to be self occluded.

Note that working with correct opacity is slower, since in that case VRayDirt must examine and evaluate the material on the occluding objects.

The diffuse layers are below the reflection and luminance layers, as they get covered by this effects full or partly, so when you have a 100% reflection you will never see the diffuse layer of course, this is physical correct and makes sense, you never see that color of a mirror, the mirror will only show the reflecting environment (At most the reflection can be tinted). In real world there are very few materials that have 100% reflectivity of course. Most materials have a Fresnel effect and show also the diffuse color. If you have a very bright luminance (100+%) you will also not see the diffuse color.

Example: V-Ray Dirt – 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: V-Ray Dirt – Consider Same Object Only

Ignore for GI: on

Example: V-Ray Dirt – 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

Example: V-Ray Dirt – Subdivisions Parameter

subdivisions: 1

subdivisions: 5

subdivisions: 20

Example: V-Ray Dirt – Radius Parameter

This parameters determines the amount of area (in units) where the V-Ray Dirt effect is produced. Notice that two of the object do not contact any other objects on their tops, so there is no dirt effect.

Simple V-Ray Material – no Dirt effect

radius: 10.0

radius: 30.0

Example: V-Ray Dirt – Texure Radius

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.

radius: 100
texmap radius: bitmap

radius: 300
texmap radius: bitmap

Example: V-Ray Dirt – Falloff Parameter

falloff: 0.0

falloff: 1.0

falloff: 5.0

Example: V-Ray Dirt – 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

Example: V-Ray Dirt – Distribution Parameter

This parameter will force the rays to gather closer. The effect is that the dirt area is being narrowed closer to the contact edges.

Rays distribution (X,Y,Z) axis
Equal angle between rays distribution
Distribution parameter = 0.0

Rays distribution (X,Y,Z) axis
Different angle between rays distribution
Distribution parameter > 0.0

distribution: 1.0

distribution: 3.0

distribution: 10.0