A whopping halo that sometimes happens sometimes doesn't

24_Seven

I had some good results in other setups where there was no halo. But then there were the times when I got it again - different scenarios. Not sure why. But when I was doing the single shot stuff at a much higher resolution it was very clean and there was no detectable halo.

This is a screen grab from a really low rez 200 x 200 animation that I did that small to save rendering time to see how it was working. For the purposes of this forum post, I blew it up so you could see the fringing without any effort. It was clear as a bell on my end to see the halo stair stepping around the figure against black. So I'm not enhancing or exaggerating the flaw other than enlarging the pic.

I mean the action was great, moved well, so the test I was doing was a success on that level as I learn this program.

Any clarity on what I'm doing that causes it would be helpful and greatly appreciated.

Oh, and another thing I've seen is that there is some kind of soft shadowy banding around the limbs of some of the characters. It's also showing up periodically. You can make it out on her right arm (to our left).

Richard Haseltine

What are your render settings, and what are your Environment pane settings? Does this happen only in animations, and if so is it only in animations you render directly to a movie file (as opposed to those rendered to an image sequence)?

It does, by the way, looks as if you need to adjust the shading rate on the SSS shader for the skin - that's probably why you have banding on the skin, though I doubt it has anything to do with the haloing.

millighost

24_Seven said:

I had some good results in other setups where there was no halo. But then there were the times when I got it again - different scenarios. Not sure why. But when I was doing the single shot stuff at a much higher resolution it was very clean and there was no detectable halo.
...

Looks like filter ringing. It happens with high contrast in your render (bright figure against dark background) and using the sinc-filter with a too big radius. Set a smaller filter size (1 to 2) and/or the catmull-rom filter in the render settings.

24_Seven

Thanks. Learn something new every day.

Okay, the problem went away. It was in fact the result of a couple things I was doing. With the settings I had it at, rendering an animation frame by frame made no improvement. Still had the halo. When I did a single frame with a 1200 x 1200 size exporting it as a png, it was perfect. All I could figure from that was that the resolution mattered to some degree.

As to rendering against a black background, I did not select that per se. But being as there was no light back there it makes sense it rendered the animation against black. However, the .png is against clear so the halo may not have shown up for that reason as well since there was no particular contrast happening in that case.

So taking the adjustment to the settings idea, I selected catmul (something new for me to look up), and took the pixel x and y to 1.0, and because I was concerned that part of the problem was the resolution, I made it a little bigger to 640 x 480.

Success. Got rid of the banding and the halo. And the render time was not a whole lot more than at 200 x 200. In future I will always test at minimum that 640 x 480 resolution. So it's one or all of the factors I changed. At least if it shows up again I know how to start dealing with it.

Anyway, thanks muchly! Solved. :-)