"Ghosting" with SwitchLayers

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rar313
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"Ghosting" with SwitchLayers

Post by rar313 » Sun Jul 17, 2016 10:23 pm

What are the correct key frame and interpolation settings when working with switch layers? I am using one to lip sync. When the interval between sub layer changes is short, I can see very briefly a bit of the previous switch layer. I have played with "step", "hold", etc. menu options, used copy previous keyframe as suggested by shonuff on you tube, etc. but I can't get this to go away. Is this just an optical illusion? Is there a tutorial on this somewhere?

I have also tried different export options including exporting as image sequence.

Thanks in advance. Thank you for all you experts who share your knowledge with us.
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Greenlaw
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Re: "Ghosting" with SwitchLayers

Post by Greenlaw » Mon Jul 18, 2016 12:41 am

That shouldn't be happening, at least I've never seen it. I usually render to frames for compositing but sometimes to movie files for tests and previews.

I've seen it in After Effects sometimes. There the 'ghosting' may have to so with a mismatch in frame-rate, or if I've re-timed a precomp on a timeline, I may be getting subframe errors. Bumping any keyframes to whole frames may fix it, and in some cases setting the frames to hold when appropriate. Depending on the retiming method you're using, you might even be able to set it not show frame blending. I'm not sure if any of this translates to ASP though--it's possible to squash and stretch keyframes in ASP, so you might want to check that this isn't shifting keys to subframes.

FWIW, I typically set Switch Layers to Step (i.e., hold) frame, but only when I'm not actually wanting interpolations between paths in different layers (this only happens you you use paths and even then you need to enable Interpolate Sublayers.) I also use Step if I'm using a Smart Bone to cycle through images but only wish to see specific images, not the 'in-between' images--in this case, setting interpolation to Copy Previous Key is a great time saver and reduces errors.

In general though, if you're keyframing the Switch Layer directly and you're not using Interpolate Sublayers, you shouldn't be seeing any blending effects there, even when you're using using a mode like Linear or Smooth.

Anyway, without seeing examples of what you're seeing, it's anybody's guess. Can you post a frame of where the ghosting occurs? If you don't see the ghosting in any still frames, my guess is that this is not an ASP issue but rather your movie player is performing some kind of on-the-fly frame blending. I can think of a few reasons why it might do this but you should be able to disable it.

If you're seeing it only after uploading to a streaming site, it's probably a mismatched frame rate problem.

If none of this applies and you don't see the blending in a still frame, it's probably an optical illusion. Try viewing the footage on a different computer--perhaps the issue is with your graphics card, display or some other hardware configuration.
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rar313
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Re: "Ghosting" with SwitchLayers

Post by rar313 » Mon Jul 18, 2016 1:50 am

I can't say it's truly blending. In 00:18 to 00:42 of this AS tutorial I see an example of what is bothering me. The mouth shapes don't seem to be completely discrete:

https://www.youtube.com/watch?v=AxbBUwxOytQ

The mouth movements are very rapid, that's why a I though an optical illusion was one possibility. Maybe nothing technically wrong, just some sort of lag in the retina or brain interpreting the video. On the other hand, I don't recall seeing this in professional animations.

Thank you for the reply!
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synthsin75
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Re: "Ghosting" with SwitchLayers

Post by synthsin75 » Mon Jul 18, 2016 2:38 am

Looks like an optical illusion (persistence of vision) to me. Being able to hold key poses for more than a second may help them read more clearly.
rar313
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Re: "Ghosting" with SwitchLayers

Post by rar313 » Mon Jul 18, 2016 2:53 am

Yes, but when lip syncing speech, how can you hold key frames for that long?


I did get some improvement by being careful about how much mouth shapes differed. For example, I narrowed one mouth shape so that it more closely matched the width of another mouth shape. So when the mouth layers changes, the extremes of the shape didn't differ that much. A mouth shape may only be in use for 2 frames. Is that something others find they must do?
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synthsin75
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Re: "Ghosting" with SwitchLayers

Post by synthsin75 » Mon Jul 18, 2016 3:52 am

You could try with interpolate sub-layers enabled for the switch, but then the phonemes need to be created from duplicates of one (so they match point count and order).

I prefer to limit how many phonemes I use, to help fast dialog read better. I use five, with the similar ones using exact duplicates.
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Re: "Ghosting" with SwitchLayers

Post by rar313 » Mon Jul 18, 2016 6:07 am

Thank you. I have satisfactory results with my revision as mentioned above. I will experiment with a few more mouth shapes in the switch layer and the interpolation of the sub layers as you have suggested.
:)
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Re: "Ghosting" with SwitchLayers

Post by Greenlaw » Mon Jul 18, 2016 10:04 am

Here's a tip that might help:

A while back, I animated lipsync for character and got a note saying that my character was pronouncing too many syllables. I don't remember the exact phrasing of the note but the explanation was that the character had too many mouth shapes. So I reduced the number of phonemes considerably but now I thought the mouth animation looked too 'snappy'.

My boss suggested adding simple layer transforms to the mouth Switch Layer so the drawings squashed and stretched during the transitions. That made all the difference! The character no longer looked like she was over pronouncing her dialog and the added transforms made the animation look smoother and more natural, even though I was actually using fewer drawings. Now I use this trick all the time.

Additional note:
You'll probably want to move the Switch Layer's origin to a logical position for the layer transforming, like the top of the mouth or maybe the center--exactly where depends on the character design and animation style. The upper teeth would make sense for a 'realistic' human jaw, and center probably looks better for a broadly acting 'toon' character.
Last edited by Greenlaw on Mon Jul 18, 2016 6:49 pm, edited 5 times in total.
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Re: "Ghosting" with SwitchLayers

Post by synthsin75 » Mon Jul 18, 2016 5:34 pm

Great tip Greenlaw. Wouldn't work for a wholly automated lip-sync, but would only be one extra pass.
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