The Firefly Problem

[Jaberwocky]

Morning Everybody

This process may be of interest.
It's not perfect, but hey...give it a try , it may work for you
The old firefly problem, caused by point lights aimed at reflective surfaces.
the first image was created to illustrate the problem.
Rendered for only two minutes using one high powered point light through a glass teapot and onto a high gloss floor in the PMC Kernal
The result...as you can see, a hell of a lot of fireflies..

options
1)..continue to let it render for a long,long time till the fireflies disappear....or a somewhat shorter time if you have 6 x GTX670's installed!
or:
2) load it into Photoshop or Elements and
A) Install this plugin

http://www.redpawmedia.com/

look for the hot pixel noise remover plugin on the web site

B) select just the areas in the image in Photoshop where the fireflies occur.
C) Run the plugin , maybe once or maybe a few times till the fireflies disappear

see the before and after images attached:
total processing time.........a hell of a lot shorter than letting the image cook for an hour or two in order to get rid of those damn fireflies.

Please note that the plugin ( which is free by the way) will only work on 8 bit images, not 16 bit, so you will need to convert it to 8 bit if you've saved the file as a 16 bit image.

[grimm]

I think the firefly's might be caustics. Try upping the caustic blur and see if that helps some. Here is a similar test I did, although with the sun/sky:

[face_off]

I assume you have tried setting hotpixel_removal to 0 in the "imager" settings? And yes, "caustic_blur" is definitely useful in this situation too. And you can reduce "direction_light_importance" to get the renderer to focus more on the non-direct light (where the fireflys are).

Paul

[Jaberwocky]

Thanks for the replies...

I created this scene to purposely generate fireflies,just to try an alternative , faster way to get rid of fireflies... rather than let a render cook for an hour.

[darkline]

Hi Jaberwocky,

Thanks for the link, but I think what face-off is asking is this any better than the built in 'hotpixel removal' post process tool in octane? It sounds like they both do the same thing, or are you saying this works better than the one you can use in octane?

If by any chance you haven't used it, you lower the hotpixel amount from 1 to start removing fireflies from the rendered image. The lower to 0 you go, the more are removed. This process is instant and does not add render time. You can play with the parameters on the fly during rendering to suit.

[Jaberwocky]

Darkline

Good point.

When I get a moment, I'll try both methods...see which one works best.!

[vinz]

thx Jaberwocky always usefull ... i'll give a try