Fireflies

ollle · Post by **ollle** » Mon Nov 13, 2006 9:36 pm

How comes that the fireflies are generated? Is it a special property of unbiased renderers? Do they disappear after long enough rendering?
I'm rendering a greeble over night and realized, that the fireflies not changed over 8 hours (yes, i know about this special parameter that can be lowered from 1000 to 100)...

ollle · Post by **ollle** » Tue Nov 14, 2006 4:37 am

Anyone?
I'm interested, what the reasons are (for generating fireflies)....

BZ Win · Post by **BZ Win** » Tue Nov 14, 2006 8:01 am

Seems to happen for me when there isn't enough light...

Sorry I can't help more.

Kachu · Post by **Kachu** » Tue Nov 14, 2006 8:48 am

from 8 - 100 mutations per pixels @ 10k max rejections. Seems like the number of fireflies go down but the intensity increases. But this was just a quick 5 minute test at low resolution.

ollle · Post by **ollle** » Wed Nov 15, 2006 4:56 am

OK, thanks for answers. My greeble image renders now for 50 hours. The fireflies disappear very slowley, but they go away....

boweeb007 · Post by **boweeb007** » Thu Nov 16, 2006 12:28 am

If what you're doing is anything like your post in http://www.indigorenderer.com/joomla/fo ... .php?t=577 then the fireflies aren't surprising. Like BZ Win said, low light, but especially INDIRECT light, will increase the time it takes for the fireflies to be calculated out. Also, make sure that you aren't using pure white (1,1,1) for any materials - use (8,8,8) instead.

ollle · Post by **ollle** » Thu Nov 16, 2006 12:37 am

boweeb007 wrote:If what you're doing is anything like your post in http://www.indigorenderer.com/joomla/fo ... .php?t=577 then the fireflies aren't surprising. Like BZ Win said, low light, but especially INDIRECT light, will increase the time it takes for the fireflies to be calculated out. Also, make sure that you aren't using pure white (1,1,1) for any materials - use (8,8,8) instead.

Yes, it's something like that, but renderwise much more difficult: Mainly indirect light (like you said). Because of the color, it's the Cinema default material, that's a light grey.
Thanks for answering.

playmesumch00ns · Post by **playmesumch00ns** » Thu Nov 16, 2006 12:46 am

Fireflies are just an artifact of monte carlo sampling. Where you get a high value from a direction with a low pdf you'll get a firefly...

There was a solution posted here a while ago: render two images, then combine them with a "min" operation, i.e. for each pixel take the minimum value from the two images. That way the random bright pixels get left out.

Fireflies

Fireflies

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