Warp wrote:

> Stefan Viljoen <spa### [at] removethispolardcom> wrote:
>> Now look at image 2 - the moment I turn on photon mapping, I get this
>> black shadowed area where the caustics caused by the glass plate are
>> supposed to appear - only it is a pitch black shadow, and STAYS that way
>> whenever photons are turned on.
> 
>   It seems to me that POV-Ray calculates the refraction of light (for
> the photons) too accurately and realistically, and what you want is just
> some fake effect which looks good, regardless of physical accuracy.
> 
>   Photon mapping is not a "magic trick" which will produce sparkling
> caustics-looking effects regardless of the object and other properties
> of the scene.

Exactly what I want in here...

> The older fake caustics (used with the 'caustics' keyword) 
> is more like that, but it's of course quite limited.
> 
>   Photon mapping calculates *accurately* how light coming from a point
> light reflects/refracts from objects and hits other surfaces. This means
> that the shape of the refracting object is quite relevant if you want to
> get sparkling beautiful caustics. Caustics are produced when refraction
> concentrates light from a larger area into a smaller area, thus
> intensifying its brightness in that area. Naturally the object must
> have a certain shape for this to happen. For example a planar sheet of
> glass will not concentrate light and thus there will be no sparkling
> caustics behind it.

Ok, that's what I was looking for as regards an explanation of what was
broken in my scene. I understand what you are saying. *sigh*

Back to the drawing board...

-- 
Stefan

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