I'm rendering an animation that involves photons. Unfortunately, even if 
I increase the photon count to the point where it takes 5 minutes to 
compute the photon maps, the image is still too grainey.

Now, for a final still, I could just crank up the photo count until it 
looks good then leave it for a few hours to finish the job. But for 
several thousand frames of animation, that's not a real hot idea. 
(Besides, you won't have time to look at it *that* hard.)

The trouble is, I can see individual "dots" of light. So I was wondering 
- is there a way to make the photons more "blurry"? (To remove the 
grainey appearence and make the caustics smoother.)

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Orchid XP v2 wrote:
> I'm rendering an animation that involves photons. Unfortunately, even if 
> I increase the photon count to the point where it takes 5 minutes to 
> compute the photon maps, the image is still too grainey.
> 
> Now, for a final still, I could just crank up the photo count until it 
> looks good then leave it for a few hours to finish the job. But for 
> several thousand frames of animation, that's not a real hot idea. 
> (Besides, you won't have time to look at it *that* hard.)
> 
> The trouble is, I can see individual "dots" of light. So I was wondering 
> - is there a way to make the photons more "blurry"? (To remove the 
> grainey appearence and make the caustics smoother.)

Hi,

I'm far from understanding all the fine tune options you can or may use 
with photons. But by looking through the docs there seem to be to 
keywords which control the appearance of photons in the final render:
   gather and radius
As far as I understood the first is to do the mandatory photon map 
building step. After photons are stored, the render trys to collects for 
each point in the scene photons in the near and probably average them 
weighted to there distance (I guess) this is the gathering step. The 
radius parameter gives you control over how far the gather routine 
should look for the photons to take into account.
So consequently by increasing the the gather parameter and radius 
parameter the photons should be blurred out. But even so it takes a 
minimum number of photons to work.
In case you have regions where caustics look good and other regions 
where photons are blotchy you may consider to adjust the corresponding 
target parameter in the objects photon block, as it controls the number 
of photons shoot in the pretrace step in an object oriented fashion.

correct me if I'm wrong, as it would help me to understand the whole 
process of photon enabled renders better.

... dave

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Orchid XP v2 <voi### [at] devnull> wrote:
> The trouble is, I can see individual "dots" of light. So I was wondering
> - is there a way to make the photons more "blurry"? (To remove the
> grainey appearence and make the caustics smoother.)

I had a lot of the same problems when I started learning photons (see
"Armillary - FINAL" posted in the image binaries by Lonnie on 8 Aug 2005)
The best solution I have found is adjusting the gather parameter.  Also, a
light sprinkling of media will tame down the grains a bit, for that matter
so can radiosity if carefully used.  In any case, if you want real world
photographic effects your render time will suffer, often dramatically.
Much of my armillary sphere rendered at less than 1 PPS and took days for
one frame.  The high number of dispersion samples and outlandish
max_trace_level was behind most of it, but that's what it took
..

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