This page provides information on the Car Paint Material.
Overview
The VRayCarPaintMtl 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.
If you just want to use the metallic flakes and make your own layered materials, you can use the VRayFlakesMtl or the newer VRayStochasticFlakesMtl material.
© Forge & Morrow
Base Layer Parameters
Base color – Specifies the diffuse color or map for the base layer.
Base reflection – Specifies a reflectivity value or map for the base layer. The reflection color itself is the same as the Base color.
Base glossiness – Specifies a reflection glossiness value or map for the base layer.
Base trace reflections – When disabled, the base layer only produces specular highlights, but no (glossy) reflections.
Flake Layer Parameters
Flake color – Specifies the color or map of the metal flakes.
Flake glossiness – Specifies the glossiness value or map of the metal flakes. It is not recommended to set this above 0.9 as it may produce artifacts.
Flake orientation – Specifies the orientation value or map of the metal flakes. The orientation of the flakes is relative to the surface normal. When set to 0.0, all flakes are perfectly aligned with the surface. When set to 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.
Flake density – Specifies the density (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. For more information, see The Flake Density Parameter example below.
Flake scale – Scales the entire flake structure. For more information, see The Flake Scale Parameter example below.
Flake size – Specifies 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.
Flake seed – The random seed for the flakes. Changing this produces different flake patterns.
Flake filtering – Determines the way the flakes are filtered. Filtering is extremely important to reduce the work required to produce a clean image. For more information, see The Flake Filtering Parameter example below
Simple – This method is 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 – This method is 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.
Flake 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 Antialiasing Filters example below.
Flake mapping type – Specifies the method for mapping the flakes.
Explicit UVW channel – The flakes are mapped using the specified channel.
Triplanar from Object XYZ – The material automatically computes mapping coordinates in object space based on the surface normals.
Flake map channel – Specifies the mapping channel for the flakes when the Flake mapping type is set to Explicit UVW channel.
Flake trace reflections – When disabled, the flakes only produce specular highlights, but no actual reflections are traced.
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 demonstrate 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 antialiasing
The result is very noisy because of the small flake size.
No filtering, Adaptive DMC antialiasing.
The result is accurate, but very slow since a lot of AA samples are required to antialias the flakes.
Flake filtering set to Simple, no antialiasing.
The filtering greatly reduces the noise, but alters the appearance of the material.
Flake filtering set to Directional, no antialiasing.
The noise is reduced and the material appearance is correctly preserved.
Example: Antialiasing Filters
Here is an example briefly demonstrating the effect of different antialiasing 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. V-Ray can use all standard 3ds Max filters (with the exception of the Plate match filter) and produces similar results to the scanline renderer.
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 or map of the coat layer.
Coat strength – Specifies the strength value or map of the coat reflections when the surface is viewed directly from the front.
Coat glossiness – Specifies the glossiness value or map of the coat reflections.
Coat trace reflections – When disabled, the clear coat only produces specular highlights, but no actual reflections.
Options
Trace reflections – When disabled, reflections from the different layers are not traced (they only produce specular highlights).
Max reflection depth – Allows you to control the maximum number of times a ray is going to be reflected by the material.
Double sided – When enabled, the material is double-sided.
Cutoff threshold – Specifies the cutoff threshold for the reflections of the different layers. This parameter is not available when the renderer is set to GPU.
Environment priority – Specifies the environment priority for the environment override texture for this material. See the VRayMtl material for more information on this parameter.
Maps
This rollout provides additional control to the different texture maps for the various parameters of the material. Some maps are only exposed here and are not accessible from the parameters section.
Base bump – Specifies the bump map for the base layer.
Coat bump – Specifies the bump map for the coat layer.
Environment override – Specifies a map for environment override.
Displacement – Specifies a map for displacement.
Notes
- The VRayCarPaintMtl 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.