Claude Mench <c.m### [at] adilinstrumentscom> wrote:
:> With photon mapping lots of photons will be shot in vain; they will just
:> end somewhere in the scene where they do not affect anything.

: I'm not sure to understand you, in photon mapping photons are not
: shoot anywhere, they are shot only in a direction of an object, never
: in a direction where is nothing.

  Suppose that the object is hidden behind other objects and in such position
that it doesn't affect the illumination of other objects.
  Photon mapping would calculate the illumination of _every_ surface, even
if that surface is not visible nor it participates in the illumination of
the scene. If a surface is partially hidden, photon mapping will calculate
the illumination of the whole surface although it wouldn't be necessary.
  Stochastic raytracing only calculates the illumination of visible
surfaces and those surfaces that participate in the illumination. Even with
partially visible surfaces it only calculates radiosity for the visible parts
and leaves the hidden parts alone (unless this hidden part reflects light
to another visible surface).

-- 
main(i,_){for(_?--i,main(i+2,"FhhQHFIJD|FQTITFN]zRFHhhTBFHhhTBFysdB"[i]
):5;i&&_>1;printf("%s",_-70?_&1?"[]":" ":(_=0,"\n")),_/=2);} /*- Warp -*/

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