Re: [Algorithms] FPS Questions

[Stephen J B. <sj...@li...>]

On Wed, 2 Aug 2000, gl wrote:

> > > executable) that perfectly demonstrate why accumlation buffer blur is
> >
> > you can use a accumulation buffer (or t buffer) to do proper motion
> blur...
> > there's nothing that prevents you from using it to do the averaging of the
> > multiple frames for each displayed frame, and that's probibly the best way
> > to go about it.
> 
> Good point.  But then of course you need to supersample the framerate.
> Which brings us neatly back to why we need higher fps in the first place.

Well, strictly, you should still use motion blur even at 60Hz or higher
because motion blur is really just *temporal* antialiasing.  The
canonical example is that even on 60Hz systems, a rapidly spinning wheel
will appear to slow down or run backwards when it revolves at speeds
higher than 60Hz (or 60Hz divided by the rotational symmetry of the
wheel).  Motion blur is the way to fix that - and in theory, you always
need it in any system that has a discreet 'frame rate'.

Unfortunately, doing *good* motion blur (not just averaging together
a bunch of static images - which doesn't really fix the temporal
antialiasing problem) is incredibly difficult - you really have
to render in four dimensions or something.

Steve Baker                      (817)619-2657 (Vox/Vox-Mail)
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