MyLittleSomethingExperimental

[lacilaci]

An early wip. I'm still having a little problem with those white dots appearing in the rendering. This is ca. 3hr+ rendering. I'm using "rawafake" sky and sun with manualy set color to 200,200,200 using any color(even just a little saturation) only with this setup I get low presence of those fireflies. Using latest legacy build...

[lacilaci]

Hi... testing new dec07_2012 legacy build to see how it handles those white spots... and no luck here. Maybe I'm doing something wrong, but it looks that lots of very dense geometry with reflection component is enough to make these fireflies appear.

[lacilaci]

I've simplified the material so it has only a diffuse color and a bit of reflection.. no masks no translucency, refraction... And I tried several different render settings nothing makes it go away. They're less prominent if I use low sky and sun intensity values but still appear here and there plus the longer the render goes the more of them seem to appear. Turning image filtering off makes them smaller turning it on with default values(cone 1,5 + internal res 2) makes less of them appear but they're bigger :D....

So either I'm doing something very wrong. Or there is a problem with reflection and lots of dense geometry...

Btw can't run assert version of corona(max will crash, not able to load plugins)

[Ondra]

ok, post the scene - http://corona-renderer.com/upload/

[lacilaci]

Ok, uploading now... Let me know if somethings missing. There is a max file and 2 proxies which goes into the Cscatterer and a ground texture... it's 2013(64bit)

[Ondra]

ok, mystery solved: you have perfect mirror reflections on the grass leaves. This combined with the geometric complexity of scattered grass causes random speckles to appear where the grass blade aligns to reflect the sunlight. You need to blur or remove the reflection on the leaves.

[Chakib]

Did you use Progressive mode or VCM here ?

Keymaster : so the reflection with scattered objects and opacity are the problem ? will remove its reflection  in my scene and see

[lacilaci]

Well... It does happen even at glossy values around 0,5 for refl. I have to blur the reflection so much that it really doesn't matter if I use any...
So, there is no way to make corona sample away this kind of artifact?

[Ondra]

Well... It does happen even at glossy values around 0,5 for refl. I have to blur the reflection so much that it really doesn't matter if I use any...
So, there is no way to make corona sample away this kind of artifact?

It is not an artifact. What you are doing is scattering tiny mirrors on the ground - it makes sense you'll see random bright flashes all over the ground where it aligns to reflect the sun. So you need to either dull the reflection, or make the sun not be visible in it (probably impossible with current set of fakes, but will be in the future)

[lacilaci]

I get it I get it!! Don't yell at me :D:D:D lol... I was just thinking that reflection would be much less visible using very low values for sun (color and intensity) and yes, hiding sun worked only for direct visibility but is seen in reflection. Thanks for help with this :) I'll make some adjustments for the materials then...

[Ludvik Koutny]

This is a bug, just not in raytracing, but in the way samples are averaged and filtered. Other renderers filter them correctly, but unfortunatelly corona just splats the superbright value onto surrounding pixels creating large white dot with very sharp border.

[lacilaci]

That makes sense since there was larger amount of smaller bright spots without image filtering and less amount but bigger spots with 1,5px cone filter. However I partially solved the issue with very low glossiness values as well as reflections so it's ok but in some cases it might be pretty tricky to correctly tonemap lightsources visible directly or in reflections to get rid of aliasing.

I'm thinking, how would you solve a situation like: night street view after rain with lots of light emiters and tons of wet reflective geometry in the background? I need to try this :D

[Ondra]

DOF the shit outta it and apply some artsy bokeh :D

[Ludvik Koutny]

I hope it will be solved soon. I consider it a bug... Other renderers handle it correctly so that you don't see such artifacts :)

[lacilaci]

DOF the shit outta it and apply some artsy bokeh :D

What a solution!! :D You should add that at the end of some future manual "...And if anything else fails DOF the shit outta it and apply some artsy bokeh..."