difference between setCutoff and setExtinct
The only mention of these that I can find can be found on page 30 of this PDF.
Hope this helps you.
No, it does not really help. I can only guess what are those parameters for without going through the source code. GVDB is a good rendering engine but it would be much better(more productive) if this library has a definitive document.
This may help you.
SetCutoff ( minval, alphacut, unused). Specifies the minimum value threshold
which should be considered for sampling. Values below this will not be rendered
but will be skipped. Alphacut specifies the smallest alpha which should result in
early ray termination. As a ray accumulates samples, its alpha decreases
(becomes more opaque). Alphacut specifies when the opacity should result in
ray termination. Both values affect the performance/quality of rendering.
SHADE_DEEP Function: gvdbRayDeep
Renders the data as a semi-transparent volume with deep,
accumulated sampling. The transfer function is applied to
each sample point. Use scene.SetSteps(…) to set the voxel-to-voxel
sample spacing for render quality, use scene.[b]SetCutoff/b to define
the minimum contributing voxel value and the alpha cutoff value,
and use scene.[b]SetExtinct/b to set the extinction and albedo
for accumulation. Use scene.SetBackgroundClr(…) to set the
background color value for semi-transparent rays.