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This page provides information on the Anti-Aliasing options in the Sampler tab of the V-Ray Renderer.

Overview

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UI Path

||V-Ray Shelf|| > ROP Parm > Renderer tab > Sampler tab

||out Network|| > V-Ray > V-Ray Renderer > Renderer tab > Sampler tab

V-Ray menu > Render Settings > Sampler tab

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What is Anti-Aliasing?

One of the functions of image sampling is anti-aliasing, which is the reduction of jagged

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One of the functions of image sampling is anti-aliasing, which is the reduction of jagged edges in a rendering. The following example shows the basic difference between an image with anti-aliasing, and one without. The left images are jagged around the edges of the sphere, while the right are smooth. 

Here we have an example of a gray sphere against a blue background. If only one sample is taken for the each of the pixels around the edge of the sphere, the choice of pixel color is limited to the dark gray at the edge of the sphereobject, or the blue (white) background. Using one of these colors (iei.e. taking only one sample) makes the image look jagged around the perimeter of the sphere. This . This is the equivalent of no anti-aliasing at all.

If two or more samples are taken in each pixel, the colors are averaged, and pixels at the edge of the sphere object end up being a color in between the dark gray of the sphere and the blue background. These in-between colors make the sphere object appear smoother in the final rendering.

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Column width 10% 20% Column width 40% 60% Before after afterLabel 24 dark true beforeLabel 1 Panel Image Added Panel Image Added Image Removed No anti-aliasing (1 sample or subdiv per pixel)   Image Removed Column width 40% 20%

Anti-Aliasing

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Anti-Aliasing

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Example: Anti-aliasing Filters

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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 zoomed in images below have been zoomed in and cropped 300%. 

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Column width 25%   Column width 50% Image slider Panel borderStyle none Filtering is off Panel borderStyle none Lanczos filter, size 2.5 Panel borderStyle none Triangle filter Panel borderStyle none Sinc filter, size 2.5 Panel borderStyle none Box filter, size 2.5 Panel borderStyle none Area filter, size 2.5 Panel borderStyle none Catmull-Rom filter Panel borderStyle none Cook Variable filter, size 2.5 Panel borderStyle none Caussian filter, size 2.5 Drag the slider to change the filter type.   Column width 25%

 

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moireEffects moireEffects

 

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ExampleExample: Anti-aliasing Filters and Moire Effects

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The scene is very simple: a sphere with a very fine checker map applied. The images were rendered with a very high sampling rate (15 subdivs, or 225 rays/pixel). This is enough to produce quite an accurate approximation to the pixel values. Note that the image looks quite different depending on the filter:

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Example: Render Mask

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Column width 10% 8% Column width 40%  Image Added Image Removed The original image   Column width 4% Column width 40%  Image Added Image Removed The same image, only objects with chrome material were re-rendered     Column width 10% 8%

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Column width 10% 8% Column width 40%  Image Added Image Removed The actual render mask image - RGB channels   Column width 4% Column width 40%  Image Added Image Removed The actual render mask image - Alpha channel  Column width 10%8%

 

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ProgressiveSampler ProgressiveSampler

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Column width 50% This section provides information specific to the Progressive Sampler Type. The Progressive sampler renders the entire image progressively in passes. The advantage of this sampler is that you can see an image very quickly, and then let it refine for as long as necessary as additional passes are being computed. This is contrast to the bucket-based image samplers, where the image is not complete until the final bucket is done. A disadvantage is that more data needs to be kept in memory, especially when working with render elements. Also, when using distributed rendering, because of the continuous refinement, frequent communication between the client machine and the render servers is required, which may reduce the CPU utilization on the render slavesservers. This effect can be controlled to some extent using the Ray bundle size parameter. Min Subdivs – Controls the minimum number of samples that each pixel in the image receives. The actual number of the samples is the square of the subdivs. Note: Not available when using a GPU-based Production engine. Max Subdivs – Controls the maximum number of samples that each pixel in the image receives. The actual number of the samples is the square of the subdivs. If zero, the number of samples is not limited. Noise Threshold – The desired noise level in the image. If this is 0.0, the entire image is sampled uniformly until either the Max. subdivs value is reached or the Render time limit is reached. Max. Render Time (min) – The maximum render time in minutes. When this number of minutes is reached, the renderer stops. This is the render time for the whole frame; it includes any GI prepasses like light cache, irradiance map, etc. If this is 0.0, the render is not limited in time. Ray Bundle Size –  (CPU) – Useful for distributed rendering to control the size of the chunk of work that is handed to each machine. When using distributed rendering, higher values may help to utilize CPUs on the render servers better. Ray Bundle Size –  (GPU) – Controls the number of samples to transfer over the network for RT-GPU. Available when using RTX rendering.  Rays Per Pixel – Controls the number of samples per pixel for RT-GPU. Available when using GPU/RTX rendering. UI Text Box type note Avoid using the  Progressive  sampler the Progressive sampler with sharpening image filters (Catmull-Rom, Mitchell-Netravali) as this may slow down the rendering - additional image samples are required to resolve sharpening filters properly. V-Ray prints a warning in this case in the V-Ray messages window.   Column width 5% Column width 45% Image Removed

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Image Added

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Example: Stages of Rendering with the Progressive Sampler

Bucket Sampler

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Example: The Threshold Parameter

This example deals with texture anti-aliasing and the effect of the color threshold for the Bucket sampler.

By default V-Ray anti-aliases everything in the image, including textures. This is especially useful for textures with small details or noisy bump maps. The Threshold parameter controls the extent to which texture anti-aliasing is performed. The effect of this parameter is most noticeable with low min rates. For the four images below, min/max rate of -3/2 was used:

Note that the edges of the object in those images are always sharp.

If you set the Threshold to a high value, you are effectively telling V-Ray not to anti-alias textures. You can use this fact to speed up the rendering of complex materials. Note however, that this disables anti-aliasing of V-Ray shadows, reflections etc as well.

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Textures

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Post Effects

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Notes

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