In Chap. 12 of Rendering with Radiance by @GregWard and Shakespeare, it is reported that a constant ambient approximation is used when the -ab number of bounces is reached in the pathtracing process.
Is this still the way Radiance deals with path termination now?
In the source code file ambient.c line 360-380, I do see some code that does constant ambient approximation. However, in the raytrace.c line 119-134, I see that the unbiased Russian Roulette is used.
I would like to confirm that for the functions like rcontrib and rfluxmtx, we are actually using Russian Roulette algorithm, right? In this case, the result should be unbiased no matter what -ab, -av or -aw parameter is given, right? In In Chap. 6.4.2 of Rendering with Radiance, the author "expect(s) the prediction for -ab 5 to be greater than those for -ab 1"; this in theory should not be the case for the tracer with Russian Roulette, right?
