These parameters allow for a finer control (on a per-object basis) over global illumination. Also refer to Global Illumination Properties.
Global Illumination object properties
Maximum Distance
Specifies maximum distance for indirect illumination. Zero means no maximum distance. Limiting the maximum distance to smaller values will accelerate rendering since less objects are considered for each traced ray.
Falloff - Type
Specifies a falloff type, this can be either 'none' or 'Polynomial'.
Falloff - Exponent
If Type is set to 'Polynomial' this will specify its exponent. For example, specifying 2 will achieve a quadratic falloff.
GI Point-Based Algorithm Bias
Specifies a point-cloud bias for point-based color bleeding evaluation. This is needed to avoid self-occlusion problems.