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horizontal flickering in a particle 'cloud' field

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steven godber
horizontal flickering in a particle 'cloud' field
on Feb 27, 2013 at 12:20:26 pm

hello folks, I've searched adobe and other places for this problem of horizontal flickering in a quick experiment i was making with particle-world in after-effects. i don't even know if 'flickering' is the correct terminology but at present jpgs don't make good search terms.

The two screenshots show horizontal lines where there should be gradation of colour. the problem is more pronounced when animated as there seems to be a glaring flicker between frames. Doubling the frame rate has had no effect.

The screenshots are of the preview but the flicker occurs even in rendered video.





I am using CS5 on an intel i7 machine, 16gig of ram and a quadro 4000 graphics card.


All help or advice would be greatly appreciated.

Cheers.


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Paul Stevenson
Re: horizontal flickering in a particle 'cloud' field
on Feb 27, 2013 at 4:14:31 pm

I have never seen that, but then again I don't really use particle world.

Just as a matter of interest what happens if you up the colour depth? I assume your working in 8bit?

Depending how it looks in motion, what you are seeing could be described as clipping.

If you can provide a download for your file or an explanation of how to recreate it I would be happy to see if it does it to me.

Oh just one thing, make sure you are using "Adaptive resolution - Open GL off" in the fast preview window. I have never seen anything I like with open GL being on.


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steven godber
Re: horizontal flickering in a particle 'cloud' field
on Feb 27, 2013 at 10:46:09 pm

hi Paul and thanks.

No, there's no difference in 16 or 32 bit mode, in fact if anything it should be worse since particle-world works best in 8 bit.

It's probably worth noting that this is something i made ages ago with cs3 on a windows machine, i can't remember if the result was as ugly then as it is now. using the same settings i re-created the comp in a new project to rule out any issues with project settings (it almost looks like an interlacing issue) but the problem persists.

and here are some screenshots of the settings i used, feel free to give it go and see what you make of it. (quite fun for next to no effort)





Incidentally, i am aware of clipping in digital audio and photography but i'm curious to know what you mean by clipping in this case …

thanks again


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Paul Stevenson
Re: horizontal flickering in a particle 'cloud' field
on Feb 28, 2013 at 4:20:21 pm

I haven't got time to try that out at the moment, but I will hopefully get to do it tomorrow.

Clipping, well that's what I call it, I suppose technically it's "clipping through". In this instance there is something behind the "cloud" that should be being obscured, but instead it's showing through. Because of the hard line it's like it's part cut through, hence the clipping.


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Paul Stevenson
Re: horizontal flickering in a particle 'cloud' field
on Feb 28, 2013 at 4:46:54 pm

Actually, I just had an opportunity and I see exactly the same thing.

I don't know now if it's a colour issue, or something odd with the colours at least.

If you set the colour space to Adobe RGB (ie quite a wide gamut) it's severely alleviated on mine.

I suspect if particle world could do 16bit it might go away.

It could be clipping through though, the particles could be moving through the others but quite how that would be helped with a wider colour gamut I don't know.


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steven godber
Re: horizontal flickering in a particle 'cloud' field
on Mar 1, 2013 at 11:00:50 am

Thanks for trying that Paul, it helps me rule out a problem of hardware.

In fact it turns out that it's likely just a case of clumsy use of Particle-World. The problem seems to occur when i raise the z-radius of the emitter, you need this reasonably high for that "comin' straight at ya" effect, the higher the figure the more powerful the effect. But too much introduces this clipping which appears to be exactly as you describe.

It's probably worthwhile finding out if the same problem occurs with Particular but for now, most importantly, hardware and settings issues are ruled out.

Thanks heaps for that, you've been a great help. And thanks for the new vocabulary ;)

Steve.


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