V-Ray GPU offers some different controls over the Progressive Image Sampler quality. Below are listed only the parameters that differ from the V-Ray ones.
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.
Noise Limit – The desired noise level in the image. If this is 0.0, the entire image is sampled uniformly until either the Samples limit is reached or the Max. Render time 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. If this is 0.0, the render is not limited in time.
Ray Bundle Size – 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.
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 amount of data transferred from the render servers back to client machine.
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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 like VRayFur, for example) and/or blurry effects (DOF, motion blur, glossy reflections, etc).
The diagram above shows visually the way V-Ray is placing samples when using the Bucket sampler. The black squares represent the pixels of the image, while the dots represent the individual samples. In the first pass V-Ray always places the minimum number of samples determined by the the Min. subdivs parameterparameter. Then the color of the samples is compared, and more are added where needed in the following passes.
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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 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 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 a maximum of 16 samplessamples). 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.
Threshold – The threshold that is used to determine if a pixel needs more samples.
Animated 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.
Use Blue Noise Optimization – When enabled, reorders the DMC samples in screen space to produce a more pleasing result for low sample counts.
Render Region Division – Determines the height and width of the sample buckets.
Width – Determines the width of the sample buckets. Height – Determines the height of the sample buckets.
