Page Contents

 

Overview


The BRDFCarPaint material is a material that simulates a metallic car paint. It is a complex material with four layers: a base diffuse layer, a base glossy layer, metallic flakes layer, and clear coat layer. The material allows the adjustment of each of these layers separately.

 

 

 

Parameters


 

 

 

Base

Color – Specifies the diffuse color for the base layer.

Reflection – Specifies the reflectivity of the base layer. The reflection color itself is the same as the Base color.

Glossiness – Specifies reflection glossiness for the base layer.

Base Bump

Mode/ Map – Specifies the type of bump map or normal map to apply to the base layer if a map file is specified.

Bump Map 
Normal Map in Tangent Space

Amount – A multiplier for the bump/normal effect.

 

Flakes


 

 

Color – Specifies the color of the metal flakes.

Glossiness – Specifies the glossiness of the metal flakes. It is not recommended to set this above 0.9 as it may produce artifacts.

Orientation – Controls the orientation of the flakes relative to the surface normal. When this is 0.0, all flakes are perfectly aligned with the surface. When it is 1.0, the flakes are rotated completely randomly with respect to the normal. Values above 0.5 are not recommended as they can produce artifacts. For more information, see The Flake Orientation Parameter example below.

Density – Controls the number of flakes for a certain area. Lower values produce less flakes and higher values produce more flakes. Set this to 0.0 to produce a material without flakes. See the The Flake Density Parameter example below.

Scale – Controls the scale of the entire flake structure. For more information, see The Flake Scale Parameter example below.

Size – Controls the size of the flakes relative to the distance between them. Higher values produce bigger flakes and lower values produce smaller flakes. For more information, see The Flake Size Parameter example below.

Mapping/ UV– Specifies the method for mapping the flakes.

Mapping Channel – Flakes are mapped using the specified channel.
Triplanar – The material automatically computes mapping coordinates in object space based on the surface normals.

Filtering Mode – Determines the way the flakes are filtered. Filtering is extremely important to reduce the work required to produce a clean image.

Simple – Faster and uses less RAM, but is less accurate. It averages the orientation of the flakes together, which may alter the appearance of the material when viewed from a distance.
Directional – Slightly slower and uses more RAM, but is more accurate. It groups the flakes based on their orientation before performing the filtering, so that the material appearance is preserved.
For more information, see The Flake Filtering Parameter example below.

Map Size – Internally the material creates several bitmaps to store the generated flakes. This parameter determines the size of the bitmaps. Lower values reduce RAM usage, but may produce noticeable tiling in the flake structure. Higher values require more RAM, but tiling is reduced. Be careful when using the Directional filtering method, as it may quickly take up gigabytes of RAM for larger map sizes. For more information, see Anti-Aliasing Filters example below.

Seed – Sets the random seed for the flakes. Changing this produces different flake patterns.



Example: The Flake Orientation Parameter

 

This set of images demonstrate the effect of the Flake orientation parameter. Note how lower values produce flakes more aligned with the surface normal, so that light is reflected more uniformly. Higher values produce more random flakes leading to more variation in the flake illumination.

 

 

Flake orientation is 0.0

Flake orientation is 0.1

Flake orientation is 0.3

 

 

 


 

Example: The Flake Density Parameter

 

This set of images shows the effect of the Flake density parameter. Note how larger values produce more flakes but do not change the flake size.

 

 

Flake density is 0.5

Flake density is 1.0

Flake density is 2.0

 

 

 



Example: The Flake Scale Parameter


This set of images demonstrates the effect of the Flake scale parameter. Note how lower values scale the entire flake structure.

 

 

Flake scale is 0.005

Flake scale is 0.01

Flake scale is 0.02

 

 

 


 

Example: The Flake Size Parameter


This set of images shows the effect of the Flake size parameter. Note how larger values make the individual flakes larger, but do not change their count.

 

 

Flake size is 0.5

Flake size is 1.0

Flake size is 2.0

 

 

 



Example: The Flake Filtering Parameter


This example shows the effect of the Flake filtering parameter.

 

No filtering and no anti-aliasing; the result is very noisy because of the small flake size.

No filtering, Adaptive DMC anti-aliasing. The result is accurate, but very slow since a lot of AA samples are required to anti-alias the flakes.

Flake filtering set to Simple, no anti-aliasing. The filtering greatly reduces the noise but alters the appearance of the material.

Flake filtering set to Directional, no anti-aliasing. The noise is reduced and the material appearance is correctly preserved.

 

 

 


Example: Anti-aliasing Filters


Here is an example briefly demonstrating the effect of different anti-aliasing filters on the final result.

Note that rendering with a particular filter is not the same as rendering without a filter and then blurring the image in a post-processing program like Adobe Photoshop. Filters are applied on a sub-pixel level, over the individual sub-pixel samples. Therefore, applying the filter at render time produces a much more accurate and subtle result than applying it as a post effect. 

The Adaptive image sampler was used for the images below, with Min/Max rate of -1/3 and the Rand option on.

 


Simple filtering
Flake map size is 256.
Flake maps take less than 1 MB .

Simple filtering
Flake map size is 512.
Flake maps take between 1 and 2 MB.

Simple filtering
Flake map size is 1024.
Flake maps take 5 MB.

Simple filtering
Flake map size is 2048.
Flake maps take 21 MB.

 

 

Directional filtering
Flake map size is 256.
Flake maps take 10 MB.

Directional filtering
Flake map size is 512.
Flake maps take 40 MB.

Directional filtering
Flake map size is 1024.
Flake maps take 161 MB.

Directional filtering
Flake map size
is 2048.
Flake maps take 645 MB.

 


 

Coat Layer Parameters


 

 

 

Coat

Color – Specifies the color of the coat layer.

Strength – Specifies the strength of the coat reflections when the surface is viewed directly from the front. 

Glossiness – Controls the glossiness of the coat reflections.

Coat Bump

Mode/Map – Specifies the type of bump map or normal map to apply to the coat layer if a map file is specified.

Bump Map 
Normal Map in Tangent Space

Amount – Multiplies the bump map effect. 

 

Reflection Options (All Layers)




Trace Depth – Specifies the maximum number of times a ray will be reflected by the material. 

Cutoff  Specifies a threshold below which reflections will not be traced. V-Ray tries to estimate the contribution of reflections to the image, and if it is below this threshold, these effects are not computed. Do not set this to 0.0 as it may cause excessively long render times in some cases.

Base Reflections – When disabled, the base layer only produces specular highlights, but no actual reflections are traced. 

Flake Reflections – When disabled, the flakes only produces specular highlights, but no actual reflections are traced. 

Coat Reflections – When disabled, the coat layer only produces specular highlights, but no actual reflections are traced. 

 

Multipliers


 

 

Mode – Specifies how textures and colors are blended by the multipliers. 

Multiplier – When set to Multiply, the texture is blended with black color. 
Blend Amount – When Blend Amount is selected, the user-specified color is used for blending. 

Base Color – Blends between the assigned texture and the mode specific color.

Base Glossiness – Blends between the assigned texture and the mode specific color.

Flake Color – Blends between the assigned texture and the mode specific color.

Flake Glossiness – Blends between the assigned texture and the mode specific color.

Coat Color – Blends between the assigned texture and the mode specific color.

Coat Glossiness – Blends between the assigned texture and the mode specific color.

Coat Strength – Blends between the assigned texture and the mode specific color.

 

Material Options


 


Can be Overridden – When enabled, the material will be overridden when you enable the override color option in the Global Switches.

Alpha contribution – Determines the appearance of the object in the alpha channel of the rendered image.

Normal (1) – A value of 1.0 means the alpha channel will be derived from the transparency of the material.
Ignore in Alpha (0)   A value of 0.0 means the object will not appear in the alpha channel at all. 
Black Alpha (-1) – A value of -1.0 means that the transparency of the material will cut out from the alpha of the objects behind. 

ID Color – Allows you to specify a color to represent this material in the Material ID VFB render element. 

Invisible for Reflections/Refractions – When enabled the objects with this material will not appear in reflections and refractions.

Optimize exclusion – Enables an alternative calculation method. This option is not recommended.

Maps


These determine the various texture maps used by the material.

Bump/Normal Mapping

Bump/ Normal Mapping – Enables or disables the bump or normal effect.

Mode/Map – Specifies the map type. 

Bump Map
Local Space Bump 
Normal map 

Amount – A multiplier for the bump/normal map. 

Advanced Options

Normal Map Type – Specifies the normal map type. 

Tangent space
Object space
Screen space
World space 

Delta Scale – Decrease the value of the parameter to sharpen the bump, increase it for more blurry effect of the bump. 

 

Displacement




Displacement – Enables or disables the displacement effect.

Mode/ Map – Specifies the mode in which the displacement is rendered. 

2D Displacement – Bases the displacement on a texture map that is known in advanced. The displaced surface is rendered as a warped height-field based on that texture map. The actual raytracing of the displaced surface is done in texture space and the result is mapped back into 3D space. The advantage of this method is that it preserves all details in the displacement map. However, it requires the object to have valid texture coordinates. You cannot use this method for 3d procedural textures or other textures that use object or world coordinates. The parameter can take any values. 
Normal Displacement – Takes the original surface geometry and subdivides its triangles into smaller sub-triangles, which then are displaced. 

Amount – The amount of displacement. A value of 0.0 means the object appears unchanged. Higher values produce a greater displacement effect. This parameter can also take a negative value, in which case the displacement pushes geometry inside the object. 

Shift – Specifies a constant, which is added to the displacement map values, effectively shifting the displaced surface up and down along the normals. This can be either positive or negative.

Keep continuity – When enabled, tries to produce a connected surface, without splits, when there are faces from different smoothing groups and/or material IDs. Note that using material IDs is not a very good way to combine displacement maps since V-Ray cannot always guarantee the surface continuity. Use other methods (vertex colors, masks etc.) to blend different displacement maps.

View dependent – When enabled, Edge length determines the maximum length of a subtriangle edge in pixels. A value of 1.0 means that the longest edge of each subtriangle is about one pixel long when projected on the screen. When disabled, Edge length is the maximum sub-triangle edge length in world units.

Edge length – Determines the quality of the displacement. Each triangle of the original mesh is subdivided into a number of subtriangles. More subtriangles mean more detail in the displacement, slower rendering times and more RAM usage. Less subtriangles mean less detail, faster rendering and less RAM. The meaning of Edge length depends on the View dependent parameter. 

Max subdivs – Controls the maximum sub-triangles generated from any triangle of the original mesh when the displacement type is Subdivision. The value is in fact the square root of the maximum number of subtriangles. For example, a value of 256 means that at most 256 x 256 = 65536 subtriangles will be generated for any given original triangle. It is not a good idea to keep this value very high. If you need to use higher values, it will be better to tessellate the original mesh itself into smaller triangles instead. The actual subdivisions for a triangle are rounded up to the nearest power of two (this makes it easier to avoid gaps because of different tessellation on neighboring triangles). 

Water Level – Clips the surface geometry in places where the displacement map value is below the specified threshold. This can be used for clip mapping a displacement map value below which geometry will be clipped. 

Level Height – Value below which the geometry is clipped. 

 

Environment Overrides 


Allows Background, Reflection, and Refraction maps from Environment Settings to override the current material.

 

 

Background – Enables the environment override. The slider works as an intensity multiplier. The checkbox allows you to assign a texture that overrides the environment for the material.  

Reflection – Enables the environment override. The slider works as an intensity multiplier. The checkbox allows you to assign a texture that overrides the environment for the material.  

Refraction – Enables the environment override. The slider works as an intensity multiplier. The checkbox allows you to assign a texture that overrides the environment for the material. 


Notes


  • The BRDFCarPaint material needs to precalculate several textures related to the flakes. Depending on the Flake map size parameter, this may take a few seconds. When working in the material editor, this may lead to slight delays between changing a parameter and the update of the material swatch