"Alberto" <jac### [at] usbve> wrote...
> Here are some considerations about photons I'd like to share.
>
>   The left image is the normal render you get with one light source.  In
> my
> opinion, the dark shadows cast by the glass are to dark.  I have
> observed
> this kind of refractive caustics in some experiments I have done with
> real
> glasses and lights, so they are right from the physical point of view as
> remarked by N. Kopp elsewhere in this newsgroups.  In the other hand,
> the
> reflective caustics are to bright.

The problem is this:

Ray-tracing assumes (incorrectly) that all of the light in the scene comes
from a single (or multiple) point light sources.  In reality, much
(sometimes the majority) of light comes from indirect diffuse interaction.

To compensate, ray-tracing artists usuall turn up the intensity of the light
source so that it is brighter than it should be.  This compensates for the
lack of diffuse interaction.  Of course, with the light source being too
bright, the caustics will be too bright.  Also, with all of the light coming
from one point, the shadows are completely void of light.  In reality, the
light source would be dimmer (making the caustics dimmer), and diffuse
interaction would make everything (including the shadow areas) brighter.

Your solution is good, though it would be better if your "fill light" was a
shadowless light.

-Nathan

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