A value of 0 switches to normal Radiance behaviour (don't use GPU).
default = 4096
-al stride
set the spacing between seed point pixels for ambient samples to stride.
(rtrace only) A value of zero will cause all pixels to be considered. This option is ignored when -az is used.
default = 0
-ag N
set the number of ambient divisions for final gather infill to N.
When -aa is non-zero, N ambient samples will be taken at points not covered by the precomputed irradiance cache. A value of -1 will cause the value of –ad to be copied.
default = -1
-az res
set the number of seed points for ambient samples to res. (rtrace only)
A value of zero will cause view-dependent seeding to be used. Thus, zero should be used in combination with the -S option in which a view file changes the view direction between frames.
default = 0
-ac N
set the number of k-means clusters for ambient calculation to N.
default = 4096
-an N
set the maximum number of k-means iterations to N.
Larger values can cause k-means calculation to take longer but will generate more accurate ambient results.
default = 100
-at thresh
set the k-means threshold to thresh.
This is the fraction of seeds that must change cluster in order for k-means iteration to continue. Smaller values can cause k-means calculation to take longer but will generate more accurate ambient results.
default = 0.05
-ax wt
set the weighting factor for position in k-means error calculation to wt.
Small values concentrate more ambient calculations around edges where ambient gradients are likely to be large.
