"Kirk Andrews" <kir### [at] tektonartcom> schreef in bericht 
news:web.47dd7cf19ebc6382a5d4a01d0@news.povray.org...
>I began playing with this scene, with no particular final result in mind, 
>so it
> has developed on its own.  But in the end, I decided I'd like to have the
> caustics of light reflected from the water playing on the bottom surfaces 
> of
> the canyon, so I added photons.  I've never really played with photons, so 
> I'm
> hoping someone more experienced with them might assist me--I'm not getting
> quite what I hoped for.
>
> I used standard photon settings.
>
> You'll notice strange artifacts along the walls of bright specks--they do 
> not
> appear until both photons and radiosity are turned on.
>
EUREKA! FOUND IT!

TEST 1: switching only media on, makes the artefacts appear again. Even with 
max_gradient 100 they do not disappear... The solution for this seems to be 
the max_trace level (see the warning in the message window). The default (1) 
is too low. Either use 2 (or higher), or switch all_intersections on. With 
max_gradient 60, no artefacts appear.

TEST 2: Switching also radiosity on, no artefacts!

TEST 3: Switching also photons on, no artefacts!

CONCLUSION: the max_trace level.

Image being rendered presently. I shall post it when finished.

Thomas

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