The RenderMan Interface - Paul Bourke

Output depth values are the camera-space z values. Depth values bypass all the above
steps except for the imager and quantization. The depth quantizer has an independent set
of parameters from those of the color quantizer.
RiPixelVariance ( RtFloat variation )
The color of a pixel computed by the rendering program is an estimate of the true
pixel value: the convolution of the continuous image with the filter specified by
RiPixelFilter. This routine sets the upper bound on the acceptable estimated variance
of the pixel values from the true pixel values.
RIB BINDING
PixelVariance variation
EXAMPLE
RiPixelVariance (.01);
SEE ALSO
RiPixelFilter, RiPixelSamples
RiPixelSamples ( RtFloat xsamples, RtFloat ysamples )
Set the effective hider sampling rate in the horizontal and vertical directions. The
effective number of samples per pixel is xsamples*ysamples. If an analytic hidden
surface calculation is being done, the effective sampling rate is RI INFINITY. Sampling
rates less than 1 are clamped to 1.
RIB BINDING
PixelSamples xsamples ysamples
EXAMPLE
PixelSamples 2 2
SEE ALSO
RiPixelFilter, RiPixelVariance
RiPixelFilter ( RtFilterFunc filterfunc, RtFloat xwidth, RtFloat ywidth )
Antialiasing is performed by filtering the geometry (or supersampling) and then sampling
at pixel locations. The filterfunc controls the type of filter, while xwidth and
ywidth specify the width of the filter in pixels. A value of 1 indicates that the support
of the filter is one pixel. RenderMan supports nonrecursive, linear shift-invariant filters.
The type of the filter is set by passing a reference to a function that returns a
filter kernel value; i.e.,
filterkernelvalue = (*filterfunc)( x, y, xwidth, ywidth );
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