V-Ray for Rhino Manual - Rum

Adaptive Subdivisions control
The default setting for Adaptive Subdivision can produce a good result. See image below on the left.
These thin lines rendered with default Adaptive Subdivisions and had some broken line in the back.
Adaptive Subdivisions Sampler
Open Image Sampler under Options, V-Ray's default uses Adaptive Subdivisions as its method of
calculating antialiasing. Default Min Rate is -1, Max Rate is 2. Same as previous discussion about Min
Rate and Mat Rate, use proper value to create accurate rendering. For this example, set the Min
rate directly to 0 will fix those broken lines, as in the image on the right.
Fix Rate Sampler
Fixed Rate Sampler works in much the same way as the Adaptive Subdivisions sampler does, but it
does not have the compacity to use multiple levels of subdivisions. Because of this, the Fixed Rate
sampler is generally quite slow, although it does produce very predictable results.
Adaptive QMC Sampler
Adaptive QMC Sampler is a very good sampler and pairs very well with using QMC for primary
bounces. Similar to QMC the Adaprive QMC Sampler is best used for scenes with lots of small
details. Although Adaptive QMC is not always the fastest method for calculating antialiasing, it
typically produces quality results.
Proper Adjustment of the Image Sampler has a direct impact on the speed and quality of the final
image. For faster previews you can decrease the Image Sampler quality. For final renders it is very
important to have a correct setting because a poor setting can produce a poor quality image even if
the lighting calculations are very precise. In all cases higher subdivisions will yield a better quality
image
V-Ray for Rhino 89