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John VanSickle <evi### [at] hotmail com> wrote:
> > Just sending all the reflected rays at once, however, can be much faster
> > in simple cases because it's done only for the reflecting surface. For example,
> > this image took just a few minutes to render:
> >
> > http://warp.povusers.org/pics/Rubiks_Revenge2.jpg
> Perhaps this can also be handled (and really, should be handled) by
> allowing the user to specify higher AA levels for certain areas of the
> screen that are believed to require it. If one object has a great deal
> of fine detail, the user should be able to specify a high AA level for
> the pixels that cover it, without forcing the whole frame to be sampled
> at that high level.
It would still be slower because the amount of rays would be doubled.
If, for example, in the above image something like 30 rays were spawned
for each reflected ray, it means that the total amount of rays traced to
for one camera sample would be 31 rays (the ray sent from the camera plus
the 30 reflected rays sent from the surface).
However, if there was a mechanism to say "if a ray hits this surface,
perform antialiasing in such a way that 30 reflected rays will be produced",
it would mean that 30 sample rays, instead of 1, would have to be traced
from the camera towards the surface, and for each, a reflected ray would
have been traced, making the total amount of traced rays 60 (30 rays sent
from the camera, plus 30 reflected rays), almost double than above.
Not that being able to specify antialiasing settings on a per-object basis
is a bad idea. It's just not necessarily the most efficient way of calculating
blurred reflections in all cases.
--
- Warp
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