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This page provides information about the Stochastic Flakes material in V-Ray for SketchUp.


Overview 


The Stochastic Flakes material results from modifying the Generic material and cannot be found in the Creation menu of V-Ray Asset Editor. The Stochastic Flakes material does not need any additional layers. It is set by removing the V-Ray BRDF layer of the Generic material and adding the Stochastic Flakes material as a layer. Applying the Stochastic Flakes material as a layer provides flexibility in creating advanced materials. 

 

 

UI Options


The Generic material settings are organized in Basic and Advanced modes. You can switch the mode from the toggle button under the Preview Swatch or globally from the Configuration rollout of the Settings tab.

An Add Layer button is provided for some V-Ray materials, including Generic. You can select an additional layer that can add up to the appearance of the material. Note that the added layers can be removed and rearranged, as shown on the Materials page.

The context options of the Color Slot allow to Copy and Paste a color from one color slot to another, as well as to reset the color selection.

A Reset option is provided in the context menu of each Number Slider. You can reset the slider value to the default one.
 

 

Base Parameters


Color – Specifies the reflection color of the flakes.

Hilight Glossiness – Controls the distribution of the flakes. A value of 1.0. makes all flakes with normals perpendicular to the surface, whereas lower values randomize the normals of the flakes.  For more information, see the Highlight Glossiness example below.

BDRF Type – Specifies the BRDF used to guide the distribution of the flakes.

Beckmann – Uses a Beckmann distribution for the flakes. 
GGX
 
– Uses GGX distribution for the flakes (the GGX distribution has a longer "tail" compared to Beckmann).

Flakes – When enabled, the material simulates flakes scattered on the surface of the object. If disabled, the material simply renders the specified BRDF type with the specified glossiness. For more details, see the Enable Flakes example below.

Mapping Type Specifies the way the flakes are scattered on the surface:

Mapping Channel – The flakes are mapped according to the specified mapping channel. The density of the flakes on the surface depends on the way the UVs follow the surface. 

Tri-Planar – The material uses tri-planar mapping to create the flakes. This mode is useful for objects that don't have suitable UV mapping.

Count – The number of the flakes expressed at the square root of the actual number of flakes in the unit texture square. For example, a value of 3000 generates 9,000,000 flakes in the unit texture square. The number of flakes is restricted to 231 (a little over 2 billion), which means the highest useful value for Num Flakes is 46340. If you need more than 2 billion flakes, increase the Scale parameter. For more details, see the Number of Flakes example below.

Scale – Controls the scale of the flakes in texture space. When Mapping Type is set to Mapping Channel, a value of 1.0 is recommended. For Tri-planar from Object XYZ mapping, the Num Flakes amount is distributed in each square unit in local object coordinates. In this case, it is necessary to lower the Flake Scale value to 0.05, 0.01, or even less, and increase the Num Flakes value depending on the object size, especially if square artifacts are observed.

Angle – Controls the "softening" of the flakes effect. Higher values produce softer results while smaller values make the flakes sharper. Usually, values between 0.5 and 0.8 are used. For more information, see the Blur Angle example below.


 

 

 

 


Example: Enable Flakes

 

 


When this option is disabled, the continuous GGX distribution is rendered.

Off
On

 

 


Example: Number of Flakes

 

 

Num Flakes = 2236 (5,000,000 flakes per unit texture square)

 

Num Flakes = 7070 (50,000,000 flakes)

 

Num Flakes = 22360 (500,000,000 flakes)

 

 

 


Example: Highlight Glossiness

 

 

Hilight Glossiness = 0.6

 

Hilight Glossiness = 0.8

 

Hilight Glossiness = 0.95

 

 

 


Example: Blur Angle

 

 

Blur Angle = 1.0

 


Blur Angle
= 3.0

 

Blur Angle = 6.0

 

 

 


 

Colored Flakes 


The Colored Flakes parameters control the color and random hue and lightness of the flakes. The correct physical behavior is that the material appears darker because the colored flakes/mirrors reflect only a certain part of the spectrum. When viewed from distance, the aggregate color of the material converges to the average color of the flakes.

Colored Flakes – Dropdown to enable Colored Flakes.

Mode – Specifies the randomization method of the colored flakes. 

Random Hue – Enables randomized hue for the flakes. 
Random from Map
 – Enables use of a texture map for randomized colors.

Saturation – Determines the saturation variation of the colors for all flakes.

Lightness – Controls the lightness variation of the colors for all flakes.

Random Color Map – Available when Colored Flakes is set to Random from Map. Specifies a texture from which random colors are sampled and applied to the flake color. Note that only the bottom-most horizontal row of pixels from the texture will be sampled; all other parts are ignored. For more information, see the Random Color Map example below.

White Average – When enabled, renders colored flakes without the darkening effect. Note that this is not physically correct.

 

 

 

 


 

Example: Random Color Map

 

The Random Color Map parameter allows the user to provide a texture map for randomizing the stochastic flake colors. It is only accessible when Colored Flakes is set to Random from Map. Random colors are generated by sampling the horizontal row of pixels at the very bottom of the map along the U-axis. The sample area is only 1 pixel tall; the rest of the map is ignored.

 

 

 


Advanced Options


Seed – The seed for the randomization of flakes. Changing this value produces different flake pattern.

Blend Min – Specifies the number of flakes per pixel below which the flakes are computed. When the number of flakes per pixel is above this value, the material gradually transitions into a smooth (non-discrete) BRDF.

Blend Max – Specifies the number of flakes per pixel above which the material only computes the smooth (non-Discrete) BRDF. If the number of flakes per pixel is below this value, the material gradually transitions into discrete flakes.

 

 

 

 

Multipliers


Mode – Specifies how textures and colors are blended by the multipliers. When set to Multiply, the texture is blended with black color. When Blend Amount is selected, the user-specified color is used for blending.

Color – Blends between the texture assigned (if present) and a color.

Hilight Glossiness – Blends between the texture assigned (if present) and a color.

 

 

 

 


All other material settings are part of the Generic material and can be found on the Generic material page.


Notes


 1 – Calculated in the default SketchUp unit - inches.