Vray problem. Black spots and small light crashes when lights are shown in renders.

[mojtabahosseini]

I don't even know how to address the issue. I feel so noob here. When I render an interior scene using any lights (from IES to meshlight) I always have these black dots appear around my lamps. I know this is a reflection bug and I know the higher my power (for IES) or Multiplier (for other lights) go, they become more.

For example in this scene, I'm using several IES lights, with 5000 unit of power. I have Vray camera and 50 shutter speed and 400 film speed. So it's pretty bright.

But when you look closely at my luster (specially at the left one, My God it's a mess), you can see white dots, with black border. I tried to clear some of them with photoshop but there are plenty of them left.

 

I know light subdivision and affect spec. Doesn't change anything, and I am pretty novice in case of numbers and stuff,but I tried 8 subdivision and 64 for the lights and they have same result (but different in render time)

 

I always put Irradiance Map to High and Light Cache to default. And noise threshold to 0.01 ... I mean I have a simple template for my renders, and I kinda not sure how that works; However I have been rendering with these settings for two years lol. I normally try not to show light sources to avoid these, but my supervisor likes lamps. I don't know why. And I'm stuck.

 

So... These black and white dots. How can I get rid of them?

[Ghiath]

hi,

 

be sure all the material should be vray , if there is one material not vraymtl will make same problem

[Corey Beaulieu]

If you tick on "Clamp Output" in your render settings, you should be able to get rid of out of range pixels (like white dots) and if that fails, try using a material override to determine of it is a material or a light issue. My guess is it's a material issue and that maybe you aren't using Fresnel. If I'm right, Clamp Output should help a lot.

[Chris MacDonald]

Are you using a sharpening antialiasing filter? These always produce horrible ringing effects like this.

 

Word of warning about using "clamp output"; it will (as the name suggests) clamp the pixel values to 16 bit values in the frame buffer, rather than being floating point and giving you the ability to tweak the exposure, save out as HDR/EXR, etc.

 

These artifacts are caused by a large difference in pixel values in floating point (hence why clamp output works) when then antialiasing filter tries to average between them. Let's say one pixel has a value of 0.5 and the one next to it has a value of 2, it will take an average of these values and arrive at 1.25 which will display as pure white. The black areas (ringing) are more than likely caused by a sharpening filter.

 

Avoid sharpening filters anyway, regardless of artifacts. They look sh*t.

Edited January 5, 2016 by Macker