Colin Doncaster <col### [at] bentanimationcom> wrote:
: Jittering the ray
: (or sample) is what gives you the blurred reflections and refractions, soft
: shadows, DOF etc..

  I think that this is an incomplete statement.
  If you send _one_ sample for one pixel and jitter this sample (ie. change
it randomly) you will certainly not get blurred nor soft anything. You will
just add noise to the image.
  To get a blur you have to send _many_ samples for that one pixel and
average the results.
  Jittering can be used here, but it's not mandatory. For example, with
area light sources you can use jittering or not. If you don't use it, you
can get color banding at the shadows if the light sources inside the area
light are too far away from each other. On the other hand, if you use
jittering (and not enough light sources) you will get noisy shadows.
You can see the uglyness of noise with the media of the official povray.
  AFAIK radiosity and photon mapping do not use jittering for this reason.

-- 
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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