[Radiance-general] PMAP simulation

[Carsten Bauer]

Roland Schregle wrote:
> Roland Schregle wrote:


> And Carsten, what *do* you really want? :^)

Money!  ... and <beep> ! and more money .. and much more <beep> !

back to business: the number of photons is both straightforward and not 
very helpful at the same time (anyway, it is more intuitive than many 
other Radiance parameters). But what do e.g. 471100 photons really mean 
in terms of accuracy or even image appearance? (my personal rule of 
thumb is: never start with less than a million photons to get anything 
good-looking :-))

But I don't have a better idea, either, and concerning the lack of 
intuitivity, the photon-map in fact fits perfectly into the rest of the
Radiance-parametermania :-) (viewed from a non-scientists point of view)

Additionally, the photon-map currently is not adaptive, distributing and
gathering are strictly separated. So controlling pmap 'form the output
end of the line', i.e. the image, is not possible now. For comparison, 
in the ambient case addtional samples (the supersamples) are produced 
if the calculation doesn't meet a given accuracy criterion.(OK, this 
accuracy criterion is again rather obscure ...)
And I know, I know, I know of course similar adaptive behaviour would be
far more complex in the pmap case. Maybe one would even end in something 
like the metropolis stuff ...

-cb