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. V-Ray includes two main image samplers, each with its own approach to sampling and its own parameters: Progressive and Bucket.
UI Path: ||Render Setup window|| > V-Ray tab > Image sampler (Antialiasing) rollout (Renderer set to V-Ray)
Column
width
5%
Column
width
45%35%
Image courtesy of Tuna Unalan
Multiple colors within a single pixel. What color should the pixel be?
...
Section
Column
width
60%
Type – Specifies the image sampler type. Depending on this choice, an additional rollout opens up below the Image sampler (Antialiasing) rollout with specific settings for that sampler type.
Progressive – Progressively samples the entire image and refines the details over time. For more information, see the Progressive Image Sampler page. Bucket – Takes a variable number of samples per pixel depending on the difference in the intensity of the pixels. For more information, see the Bucket Image Samplerpage.
Lock noise pattern - When enabled, the sampling pattern is the same from frame to frame in an animation. Since this may be undesirable in some cases, you can disable this option to make the sampling pattern change with time. Note that re-rendering the same frame produces the same result in both cases.
Anchor
RenderMask
RenderMask
Render mask – Enables the use of a render mask to determine 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 as the render window and Type set to Bucket. The following choices are available:
None – A render mask is not used. Texture – Render mask is a texture. Black values in the map define pixels which are not rendered. Pixels with any other values are rendered. The texture should use the screen mapping type. Selected – Only pixels that belong to the currently selected object(s) are rendered. V-Ray still calculates the entire image, but only renders parts that belong to the selected object(s). This mode is useful if you want to isolate or re-render just some objects from the scene. Include/Exclude list – Same as Selected, but objects are selected by list. Layers – Renders only objects that belong to the currently selected layer. Object IDs – Renders only objects with specified Object IDs. Separate Object IDs with a comma (,).
For more information on how to use the Render mask feature see the Render Mask tutorial.
UI Text Box
type
note
If the semi-transparent objects are in front of the Render-Masked ones, they still appear in the render.
Min shading rate – Controls the number of rays shot for Anti-aliasing (AA) versus rays for other effects like glossy reflections, GI, area shadows, etc. This setting is especially useful with the Progressive image sampler. Higher values mean that less time is spent on AA, and more effort is put in the sampling of shading effects. For more information, see the Min Shading Rate Example.
? button – Opens Chaos documentation on Image Sampler.
