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Strange black lines/dots in 3D comp

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Sander Broos
Strange black lines/dots in 3D comp
on Feb 1, 2018 at 9:22:14 pm
Last Edited By Sander Broos on Feb 1, 2018 at 9:28:30 pm

I'm working on a 3D city fly-through in the style of Blade Runner 2049 and use a number of pre-comps for separate buildings, like in Video Copilot's 3D City tutorial (http://www.videocopilot.net/tutorials/3d_city/). I also have a lot of snow particles. The video usually looks fine, but sometimes (it seems very random), when I change a tiny thing, or the preview resolution, the video starts to look weird (and this is often fixed when I close After Effects and restart after a while). Some 3D layers start to get a square with very strange black shimmering lines/dots. This sometimes appears immediately, but also sometimes a couple of frames into a RAM preview. They flicker a lot, and disappear and reappear randomly. Some layers also get black aliased outlines, and there's a strange bright shape in the upper half of the frame. It's rather hard to describe, so here's a picture of how it's supposed to look:

And this is how it looks when the issue appears (as you can I added some buildings and adjusted the color grading, but the issue also popped up before these changes):

Does anyone have an idea what might cause this and how to fix it? I'm only using built-in plug-ins in AE CS5.5 and Trapcode Particular. Right now restarting it seems to work (sometimes the issue remains though), but the bug is getting annoying and I'm afraid it'll appear when I render the final video.


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Dave LaRonde
Re: Strange black lines/dots in 3D comp
on Feb 1, 2018 at 11:10:28 pm

You're not trying to run AE CS 5.5 on a machine with a new OS like Win 10 or High Sierra or something, are you?

New OS - older software - potential problems.

Dave LaRonde
Promotion Producer
KGAN (CBS) & KFXA (Fox) Cedar Rapids, IA


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Walter Soyka
Re: Strange black lines/dots in 3D comp
on Feb 2, 2018 at 11:00:11 am

Do you have multiple 3D layers that occupy the same exact point in space? Try pushing one forward or back 1 pixel in Z-space so they don't intersect on the same plane.

Walter Soyka
Designer & Mad Scientist at Keen Live [link]
Motion Graphics, Widescreen Events, Presentation Design, and Consulting
@keenlive [twitter]   |   RenderBreak [blog]   |   Profile [LinkedIn]


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Sander Broos
Re: Strange black lines/dots in 3D comp
on Feb 2, 2018 at 4:16:20 pm

I actually am running it on Windows 10, I didn't know that could result in any problems because it has worked fine for me the past year and a half...
And I had already checked if I had any intersecting layers but that is not the case.


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Walter Soyka
Re: Strange black lines/dots in 3D comp
on Feb 2, 2018 at 5:53:01 pm

[Sander Broos] "And I had already checked if I had any intersecting layers but that is not the case."

Do you also have some lens flares in there? If you're using Optical Flares for those, does it matter if change from GPU to CPU rendering?

Walter Soyka
Designer & Mad Scientist at Keen Live [link]
Motion Graphics, Widescreen Events, Presentation Design, and Consulting
@keenlive [twitter]   |   RenderBreak [blog]   |   Profile [LinkedIn]


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Sander Broos
Re: Strange black lines/dots in 3D comp
on Feb 3, 2018 at 12:57:07 am

I don't have any Optical Flares, but I think I've found the source of the problem (still don't know the reason or how to stop it from happening again): Fractal Noise. I use fractal noise to generate the white lights on the buildings. When the glitch happens, I go into that precomp, to the layer of that side of the building, switch Fractal Noise off and on, and the glitch disappears in the main comp. I have no idea why this happens but at least I now have a quick solution for it...


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Sander Broos
Re: Strange black lines/dots in 3D comp
on Feb 25, 2018 at 5:06:46 pm

The problem is definitely Fractal Noise, and although I thought I had a fix for it by switching it off and on, the issue often pops up in the middle of rendering the video. I'm thinking of getting rid of Fractal Noise in my compositions altogether, but have no idea how to approach such a thing. Is there a way to replace all the black solids in my project with an image of white dots/actual building windows, while keeping the dimensions of the solids so the 3D models stay the same? If I have to I'll do this one by one for each solid.


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Cassius Marques
Re: Strange black lines/dots in 3D comp
on Feb 26, 2018 at 1:37:15 pm

create your image in the right dimensions, in the project pannel, alt drag it over the solid footage. It will replace all instances of the solid with the image.

Cassius Marques
http://www.zapfilmes.com


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