Strange Rendering Artifact

Support Compositing and Post Processing
#1

Hello, I’m new to these forums (I wonder how many people have started a post with that before) and I have a problem. I was rendering a scene when I got the following

Glitch.png960×540 51.9 KB


Notice the weird pixels around the edge of the ball, I don’t know if that is because both the ball and the plane have reflective surfaces or what but its kinda’ annoying. By the way everyone probably knows that this is a TRON effects test by now. I wanted to figure out how to make a light ribbon. I know this is off-subject but if anyone knows how to do that, a few hints or a brief step-by-step outline would be great. Also, if anyone has some criticism accompanied by a helpful tip on the scene itselfthat would also be appreciated. Thx. :smiley:

#2

Here is a Tron style light cycle.

#3

I am not on a very good screen at the moment, but I don’t see much of a problem other than simple aliasing issues (the “jaggies”), which you can solve by increasing the number of alias samples, and/or turn on full sampling (this last one is most useful when you’re doing tricky stuff with the compositor).

#4

I am on a calibrated screen and I see a black mask on a gray background and a cyan glow :smiley:
Looking very carefully I can spot the truncated sphere.

But as benu said, all I see is the aliasing between the lightband and the sphere.
It´s normal. AA works nice between similar colors or close shades of colors and when there´s a lot of stuff happening pixelwise.
Your´s is one of the worst case scenarios, black against “close-to-white” there are almost 256 steps between those two colors you need to blur.

You got two options, increase AA samples or downscaling.
Prior is done in the render settings. If it´s not enough, you got do use latter.
You render in 4 or 8 times the size and scale the image down again by 4 or 8 times. Optionally you can blur the image before downscalling.

You could ofc. just blur the render-result with postpro, however you´ll loose detail. Thats why one uses downsampling.

#5

Thanks for the great response. I don’t know if I was clear enough in my original post but the problem that bugged me was not the pixels between the lightband and the truncated sphere (why say “Ball” when “truncated sphere” is available? :)) but if you look closely (like, really close) the pixels on the edge of the ball are dark gray. It’s like a little speckled-gray outline. I looked at it again and it’s so small that it doesn’t seem as bad to me as it did yesterday but it still would be nice if I could bet rid of it.

#6

Ah – I see it.
You might want to try rendering to a different image type, especially if you’re currently rendering to jpeg images.
You could also upload the .blend; that way we can see your specific settings and offer more detailed suggestions.

#7

Tnx. It dissappeared for now but if it happens again i’ll keep that in mind.

#8

Is there any compositor work in there? It looks like a bad key or un-premultiplied overlay.