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This page provides information on VRscans.

 

Page Contents

 

Overview


The VRayScannedMtl material allows the rendering of scanned BRDF material data stored in .vrscans files. These files are produced by Chaos Group's own internal material scanner and accompanying material creator software.

 

The VRayScannedMtl material requires a separate license to work correctly. Without a license, the material will not show its UI and will render with a watermark, but otherwise it should be able to render the sample scenes below.

 

The scanned material renders the captured the appearance of an actual physical material sample, that has been scanned with special scanner hardware. The material goes beyond single-point BRDF capture and can faithfully represent the textured appearance of a large number of real-world surfaces using bidirectional texture function (BTF) approximation.

Because the scanned material simply reproduces the way a physical material responds to light, is has no notion of "diffuse" or "reflection" components, "normal" or "bump" maps.

Currently the material can render only opaque surfaces. Also, for the moment except for some general tint control, the material is unmodifiable - i.e. you can't change glossiness, increase reflectivity etc. You can only change the overall tint of the material. In its present form the material is targeted at users that need to match exactly a given real-world sample.

The .vrscan files tend to be quite large as they need to pack a lot of data (they need to describe the BRDF of the material over its entire surface).


For more details on VRscans, please see the VRscans documentation space for information on downloadable sample scenes and Frequently Asked Questions or visit the VRscans.com website.

 

 


 

UI Path: ||Material Editor window|| > Material/Map Browser > Materials > V-Ray > VRayScannedMtl

 

Parameters


General


 



File – The file name with the data for the scanned material; usually has a .vrscan extension.

Adjust UV tiling to an object – The .vrscan file stores information about the physical size of the scanned sample and by clicking on a point over a given object, the texture tiling is modified so that the texture is with the correct size for the clicked point.

Viewport UV borders – Displays the borders of the material tile in the viewport on the objects that have the material applied. This only works with the DirectX viewports.

Plain materials strategy – Simplifies the shading of the material and may help to reducing tiling artifacts. 

None – The full material evaluation is always used. The object must have valid UV coordinates.
Average BRDF – Averages the BRDF and can be used to speed up the rendering for previews. Because texture details are removed, this also removes any tiling artifacts that might arise if the scanned sample does not tile very well. UV coordinates are still needed because most BRDFs are slightly anisotropic.
Average symmetrize BRDF – Averages the BRDF and removes any anisotropy. This mode can be used on objects without proper UV coordinates.
Scramble – Useful to reduce tiling artifacts for isotropic materials with small details like car paint with flakes.

Filter color – A color multiplier for the material sample and can be used to tint the material.

Information – The text field displays some useful information contained in the .vrscan file, like the actual material sample size.

 

Advanced


 



Subdivision – Controls how many reflection rays will be traced for the material. Note: The material does not have a "diffuse" or "reflection" component - everything is considered glossy reflection.

Trace depth – Controls the number of reflection bounces. A value of -1 means that the reflections bounces are controlled by the global V-Ray trace depth in the Global switches rollout of the renderer settings.

Cut-off – A threshold that is used to speed up reflections. If the contribution of reflections falls below this threshold, the reflections are not traced. This is similar to the cut-off threshold of the VRayMtl material.

Glossy as GI – Useful for debugging purposes and is equivalent to the same setting in the VRayMtl material.

Coarse indirect – Simplifies the calculations of the material when it is viewed through GI rays. In that case the Average BRDF method is used to shade the material (see above).

Uniform reflection distribution – When enabled, the material reflections are computed by sampling the hemisphere uniformly. When disabled, importance sampling is used to put more rays in directions where the material contribution is larger. Which method will perform better depends on the scene lighting and the particular material that is used.

 

Clear coat


 



Enable – Enables the tracing of a clear coat layer for the material.

Highlights – Enables highlights from point light sources for the coat layer.

IOR – Determines the IOR of the coat layer and from that controls the strength of the reflections. A value of 1.0 does not produce any reflections and disables the coat layer. Higher values produce stronger clear coat reflections. The .vrscan files typically contain the correct value for this parameter and it is set automatically when the file is loaded.

Bump multiplier – The coat layer has a built-in bump map stored into the material sample file. This allows you to control the strength of that bump.

 

Coordinates


This is a standard 3ds Max rollout used to control how the material is applied to objects.

 

Material Optimization


Antialiasing Settings

The easiest way to optimize antialiasing is to use the Progressive Image Sampler. This approach can be a little bit slower but it doesn’t require complete understanding of the sampling in V-Ray and will work for any scene. The settings to use are:

Sampler type: Progressive
Min Shading Rate:
1
AA filter:
Enabled
AA filter type:
Lanczos
Size:
2.5
Min subdivs:
1
Max subdivs:
200
Noise threshold:
0.01
Max. render time (min):
 you will set this value based on the time you want V-Ray to render for

 

 

 

Using the Adaptive image sampler can sometimes produce the same result for slightly faster render times but it requires that you experiment with different settings and have a good understanding of how sampling works inside V-Ray.

A good starting point for high quality rendering is:

Sampler type: Adaptive
Min Shading Rate:
1
AA filter:
Enabled
AA filter type:
Lanczos
Size:
2.5
Min subdivs:
1
Max subdivs:
33
Threshold:
0.01

 

 

 

For darker images you may need to slightly increase the Min Subdivs up to 4. To further increase the quality, you need to first start by slightly decreasing the Threshold and then increasing the Max subdivs in small steps one after the other.

For a quick render to assess quality use the following settings for the Adaptive Sampler:

Min subdivs: 1
Max subdivs:
11
Threshold:
0.03

 

 

 

Global Illumination

The V-Ray Scanned material is a purely reflective material (it doesn’t have a diffuse component), this means that for scenes that are comprised of V-Ray Scanned materials entirely you do not need to enable GI.

If you still want to use GI use the settings below:

Primary Bounce (Primary engine): Brute Force – use the default settings for Brute Force
Secondary Bounce: (Secondary engine)
Light Cache
Subdivs
: 2000 for simpler exterior scenes and 4000 for interior scenes where light bounces a lot
Sample Size
: 0.02
Store Direct Light:
Enabled
Use light cache for glossy rays (Use for glossy rays):
Enabled
Filter type (Filter):
None
Prefilter:
Enabled
Prefilter samples:
10
Depth (Bounces):
10
Use retrace threshold (Use for glossy rays):
Disabled

 

 

 

Scanned Material Options

The V-Ray Scanned Material options should rarely be adjusted beyond the following values:

Subdivisions: 8
Trace Depth
: 5
Cut off:
0.01
Retrace (Don’t use GI for rays shorter than):
0
Displacement (Edges Displacement):
only enabled when there are close ups of materials that have some bumps
No Prim GI (Don’t use GI for primary rays):
Enabled