Versions Compared

Old Version 2

changes.mady.by.user Kristina Gaytandzhieva

Saved on

compared with

New Version Current

changes.mady.by.user Kristina Gaytandzhieva

Saved on

Key

  • This line was added.
  • This line was removed.
  • Formatting was changed.

...

Section
Column
width50%

In V-Ray, an image sampler refers to an algorithm for calculating a pixel's color based on the colors within and around it.

Each pixel in a rendering can have only one color. To get the color of a pixel, V-Ray calculates it based on the object's material, direct light striking the object, and indirect lighting in the scene. But within a single pixel there might be multiple colors, which may come from multiple objects whose edge intersect at the same pixel, or even difference in brightness on the same object due to changes in object shape or falloff and/or shadowing of light sources.

To determine the right color for such a pixel, V-Ray looks at (or samples) colors from different parts of the pixel itself as well as the pixels around it. This process is called image sampling. Different image sampling methods are discussed below.


UI Path: ||Properties Editor|| > Render > Sampler tab


UI Expand
title||Properties Editor|| > Render > Sampler tab

Column
width5%


Column
width45%


Image courtesy of Tuna Unalan

Multiple colors within a single pixel. What color should the pixel be? 


...


What is Anti-aliasing?

 

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. 

...

Section
Column
width20%


Column
width60%
Before after
afterLabel24
darktrue
beforeLabel1
Panel

Panel

Column
width20%



Progressive Sampler


Tabs Container
directionhorizontal
Tabs Page
titleV-Ray
Section
Column
width50%

Sampler Type

 –

– Specifies the image sampler type:

Progressive – Progressively samples the entire image. See the Progressive Sampler for additional parameters.
Bucket – Takes a variable number of samples per pixel depending on the difference in the intensity of the pixels. See the Bucket Sampler section for additional parameters.

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.

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.

Noise

Threshold

Limit – 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 In 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 – Useful for distributed rendering in order 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.

UI Text Box
typeinfo

Unlike the bucket image sampler, the Progressive sampler doesn't have a mechanism to recover if a DR server goes offline during rendering before sending back the results from its calculations. The render process may hang indefinitely, waiting for the missing data to arrive. This will be corrected in a future release.

Anti-Aliasing Filter

Filter Type – Specifies the filter type to be used for anti-aliasing. V-Ray supplies eight types of Anti-aliasing filters: None, Area, Box, Catmull-Rom, Cook Variable, Gaussian, Lanczos, Mitchel-Netravali, Sinc, and Triangle. Each has advantages and disadvantages, which make them useful for different tasks. 

Size – Determines the size of the filter in pixels. Higher values yield blurrier results. To produce physically accurate results, the minimum value of this parameter is 1.000, and the maximum value is 20.000.  For more information, see the Anti-aliasing Filters example and the Anti-aliasing Filters and Moire Effects example below. 

Render Mask

Type – Enables the render mask feature. The render mask allows you to define which pixels of the image are calculated. The rest of the pixels are left intact. This feature works best with the V-Ray frame buffer and the Bucket image sampler. The following types are available:

Disabled – The render mask is not used.
Texture – A texture map is used for the render mask. Black values in the map define pixels that are not rendered. Pixels with any other values are rendered. 
Object – A custom set of objects to render can be defined.

V-Ray GPU supports only Box, Area, Lanczos, and Gaussian filter types.

 
Object IDs – Only objects with specified Object IDs will be rendered; you can list more than one by using commas to separate them.

For more information, see the Render Mask example .

Column
width5%


Column
width45%

Image Added

30%
Tabs Page
titleV-Ray GPU


The Rays Per Pixel and Samples Limit options are unique to V-Ray GPU. 

Section


Column
width50%

Sampler Type – Specifies the image sampler type:

Progressive – Progressively samples the entire image. See the Progressive Sampler for additional parameters.
Bucket – Takes a variable number of samples per pixel depending on the difference in the intensity of the pixels. See the Bucket Sampler section for additional parameters.

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.

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.

Noise Limit – 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 – Useful for distributed rendering in order 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.

Rays Per Pixel – The number of rays that are traced for each pixel during one image pass. The greater the value, the smoother the picture from the very beginning of the rendering with GI, but interactivity may be significantly diminished. Increasing this value also reduces the amount of data transferred from the render servers back to client machine.

Samples Limit – Determines the maximum number of samples that each pixel in the image receives. V-Ray performs adaptive sampling on the image, trying to put more samples into areas that have more noise. If the Samples Limit is set to 0, V-Ray renders with the default value of 2500.

UI Text Box
typeinfo

Unlike the bucket image sampler, the Progressive sampler doesn't have a mechanism to recover if a DR server goes offline during rendering before sending back the results from its calculations. The render process may hang indefinitely, waiting for the missing data to arrive. This will be corrected in a future release.

Anti-Aliasing Filter

Filter Type – Specifies the filter type to be used for anti-aliasing. V-Ray supplies eight types of Anti-aliasing filters: None, Area, Box, Catmull-Rom, Cook Variable, Gaussian, Lanczos, Mitchel-Netravali, Sinc, and Triangle. Each has advantages and disadvantages, which make them useful for different tasks. 

Size – Determines the size of the filter in pixels. Higher values yield blurrier results. To produce physically accurate results, the minimum value of this parameter is 1.000, and the maximum value is 20.000.  For more information, see the Anti-aliasing Filters example and the Anti-aliasing Filters and Moire Effects example below. 

Animated Noise Pattern – 

Render Mask

Type – Enables the render mask feature. The render mask allows you to define which pixels of the image are calculated. The rest of the pixels are left intact. This feature works best with the V-Ray frame buffer and the Bucket image sampler. The following types are available:

Disabled – The render mask is not used.
Texture – A texture map is used for the render mask. Black values in the map define pixels that are not rendered. Pixels with any other values are rendered. 
Object – A custom set of objects to render can be defined. 
Object IDs – Only objects with specified Object IDs will be rendered; you can list more than one by using commas to separate them.

For more information, see the Render Mask example.

Column
width5%


Column
width
45%
Image Removed

Image Added






...

Anchor
AAF
AAF

Example: Anti-Aliasing Filters

...

Section
Column
width5%


Column
width30%

Image Modified

Filtering is off.

 

Image Modified

Lanczos filter, size 2.5


Image Modified

Triangle filter

Column
width30%

Image Modified

Sinc Filter, size 2.5


Image Modified

Box Filter, size 2.5


Image Modified

Area filter, size 2.5

Column
width30%

Image Modified

Catmull-Rom


Image Modified

Cook Variable, size 2.5


Image Modified

Gaussian, size 2.5

Column
width5%


...

Section
Column
width50%

Lock Subdivs – Sets a fixed number of samples taken for each pixel.

Min Subdivs – Determines the initial (minimum) number of samples taken for each pixel. You will rarely need to set this to more than 1, except if you have very thin lines that are not captured correctly, or fast-moving objects if you use motion blur. The actual number of samples is the square of this number (e.g.  4 subdivs produce  subdivs produce 16 samples per pixel).

Max Subdivs – Determines the maximum number of samples for a pixel. The actual maximum number of samples is the square of this number (e.g. 4 subdivs produces subdivs produce a maximum of 16 samples). Note that V-Ray may take less than the maximum number of samples, if the difference in intensity of the neighboring pixels is small enough. V-Ray GPU's default Max subdivs value is 48.

Noise Limit – The threshold that will be used to determine , if a pixel needs more samples.

Adaptivity Clamp – Specifies an intensity limit for the samplers to avoid excessive sampling of overexposed areas. Lower values mean a lower limit and potentially noisy overexposed areas. Higher values produce more samples in overexposed areas.

Firefly Removal – This option is available in the Bucket Sampler type only. Removes fireflies from the render and optimizes the render times. Further, it removes the flickering effect in animations. Lower values are less aggressive at removing fireflies while higher values are more effective but can start removing actual parts of the image such as small bright highlights. This option is not available with V-Ray GPU.


Anti-Aliasing Filter

Filter Type – Specifies the filter type to be used for anti-aliasing. V-Ray GPU supports Box, Area, Lanczos, and Gaussian filter types. Each has advantages and disadvantages, which make them useful for different tasks. 

Size – Determines the size of the filter in pixels. Higher values yield blurrier results. To produce physically accurate results, the minimum value of this parameter is 1.000, and the maximum value is 20.000.  For more information, see the Anti-aliasing Filters example and the Anti-aliasing Filters and Moire Effects example below. 


Render Mask

Type – Enables the render mask feature. The render mask allows you to define which pixels of the image are calculated. The rest of the pixels are left intact. This feature works best with the V-Ray frame buffer and the Bucket image sampler. The following types are available:

Disabled – The render mask is not used.
Texture – A texture map is used for the render mask. Black values in the map define pixels that are not rendered. Pixels with any other values are rendered. 
Object – A custom set of objects to render can be defined. 
Object IDs – Only objects with specified Object IDs will be rendered; you can list more than one by using commas to separate them.

For more information, see the Render Mask example .

Column
width5%


Column
width45%

Image Added


Bucket Options

...

Section
Column
width50%

Bucket Size – Determines the maximum region width/height size of the bucket (width and height are equal) in pixels.

Sequence – Determines the order in which the buckets are calculated.

Top-Bottom – Buckets are calculated from top to bottom.
Left-Right – Buckets are calculated from left to right.
Checker – Every other bucket is calculated, creating a checker-like pattern of calculated buckets.
Spiral – Buckets are calculated in a spiral pattern.
Triangulation – 
Hilber curve – 
Random – Buckets are calculated in a random order.

Reverse Sequence – Reverses the bucket calculation order.Reverse Sequence – 

Column
width5%


Column
width30%45%

Image RemovedImage Added



...

This sampler makes a variable number of samples per pixel based on the difference in intensity between the pixel and its neighbors.

 

 

This is the preferred sampler for images with lots of small details (like VRayFur for example) and/or blurry effects (DOF, motion blur, glossy reflections etc).

...