GrimDude <vos### [at] yahoocom> wrote:
: I have tried a few variations of motion blur with the system seen here. If,
: anyone can tell me how to more realistically represent acceleration in the
: blur, I would like to hear it!

  You seem to have the same misconception about motion blur as most other
people have as well. The misconception is that the motion blur leaves a
trace behind the object, but the object itself is more or less sharp.
  I think that this is a consequence of artistic effects used in cartoons
(they draw lines in the path the obect has travelled to indicate that the
object is moving very fast). Although this artistic effect works for cartoons,
it has nothing to do with reality.

  In photography motion blur is caused by an object moving while the shutter
is open so that it leaves an equally weighted trace on the film. The reason
why it looks fainter than the static objects is that the light coming from
the moving object hits each point less time than static objects, thus
imprinting a dimmer "image" at that point. Some parts of the object look
semi-transparent because the object gets out of the way of whatever was
behind it (or the other way around).

  This means that if an object moves with a constant speed it leaves an
equally blurred trace on the film. The object is not sharper in one place
and more blurred in another.
  If the speed is not constant but accelerating, the amount of blur changes
as well, but still there's no sharp version of the object (unless it's most
of the time static and moves only a fraction of the time the shutter is open;
still this fraction of time has to be very small, like 1% to get a sharp
picture of the object).
  Specifically, with constant acceleration you get a constant (linear?) change
in the blur amount. This is the case of a falling object, for example.

  To get a photographically correct motion blur you should just define your
object with its motion path and let megapov do the rest. Don't try to
"correct" the calculations of megapov by adding additional static instances
of the object. If you do, you are just making a physically incorrect image.

  In this case your objects have quite complicated accelerated motions
(it's not even constant acceleration) so you should be precise in your math.

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

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