sampling

###What is sampling?### In computer graphics images are precisely painted by a computer program based on numbers. To know what color to draw for each pixel the program needs to perform many calculations and then estimate the final color for that single pixel. The precision in the result is determined by the amount of meaningful computations performed which is also called taking samples. (Lightyear)

###Properties > Render > Sampling### Pixel Variance, a tolerance value used to determine when to automatically calculate additional samples. A lower value may reduce noise at the cost of more samples. (?)
Min Samples, used to set a required minimal level of samples for each pixel.
Max Samples, used to limit the maximum amount of samples any pixel may receive.
Specular Depth, used to limit the maximum amount of bounces for reflections and refractions.
Diffuse Depth, used to limit the maximum allowed bounces for diffuse (dull) light-rays.

The sampling Depth budgets may be overridden by Trace sets or object specificly in Properties > Object > Ray Tracing > Override Default Ray Tracing.