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Horizontal Panning Animation Judder Problem

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Hermie CabritoHorizontal Panning Animation Judder Problem
by on Aug 21, 2015 at 3:56:24 pm

So we are making this animated film and in this particular sequence, we have to scroll a very long panel where we have animation going on along with live characters. The problem we have encountered is very unique to this type of horizontal movement. The character animations go on smoothly when the position of the whole frame is locked but when horizontal movement is applied to the whole comp, that's when you notice the judder/jitter/strobe or more scientifically called "stroboscopic effect" which we didn't know existed until now.

We have tried the obvious motion blur which should have been able to handle it but even with feature turned on, it still happens. Motion blur applied to other animations, fine... but with horizontal scroll, it doesn't seem to affect it. We have tried changing the frame rate but it seems to persist even at 60fps. Forcing motion blurs did affect it but it blurs the whole thing overall and the problem is still noticeable. Those were the tips found on this particular link which I've also read in the forum. As a last resort, we even tried Reel Smart Motion Blur from Re:Vision Effects but it just made the motion blur for the animation better/smoother, the problem with the horizontal motion is still there...

We know this is not a playback issue and we don't know what else to do. Here's a link to the sequence we're talking about, We really hope there some kind of solution for this...

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Kalle KannistoRe: Horizontal Panning Animation Judder Problem
by on Aug 21, 2015 at 6:17:37 pm

That article you've linked to covers just about everything there is to know.

The 7-second rule: In the beginning your foreground room passes by in about half that time. Then at the other critical point, where there is the gate with text above it, it travels across the screen in about 5 seconds. Those seem to be the biggest problem points.

The horizontal motion also changes speed at times. It actually speeds up right when you're trying to read the sign. It should remain even, or at least change very gradually so you don't notice it.

I did a motion blur test and added the Pixel Motion Blur effect with 360 shutter angle, 8 samples. It smoothed the motion considerably but left a slight jump about once a second. This may be due to frame rate difference in your project and Youtube or some other frame-rate conversion issue. Looks like what you get converting 25 frames per second to 24 frames per second or something similar.

My advice: Slow the whole scrolling motion down to 50% and even it out by using just two keyframes for the motion. You can ease in and/or out of the motion, but it needs to be slower. And use motion blur -- it will look blurry, but the slower the motion the less blur is needed. It is not infrequent that I use 360 degree shutter angle to smooth soething out. The animated characters themselves also need motion blur, otherwise they will have that "strobo" effect. Pixel Motion Blur works quite good for that.

In fact, I'll attach a project where I've slowed down the footage to 50% using Pixel Motion frame blending and then added Pixel Motion Blur. You can render it out and see the effect this has on the jitter. Probably not HOW you want to do this, but you'll see what I mean.

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Hermie CabritoRe: Horizontal Panning Animation Judder Problem
by on Aug 22, 2015 at 3:20:01 am

i can't wait to test the project file attached, but right now i don't have access to a CC version of AE

so basically, we have to set every layer to "pass" the frame in 7-seconds or more right? how about the parallax, how do we address the different levels of movement per layer? it seems that the pan will be slower over all or do we have a different computation that will work if we want the layer to pass faster than the others?

too much blabbering for me, i guess i'll have to test the project file first, just the thought that there's a solution for this got me all excited ^_^

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Kalle KannistoRe: Horizontal Panning Animation Judder Problem
by on Aug 22, 2015 at 6:59:42 am

You don't have to set everything to pass for 7 seconds, but if you have something that you want the viewer to see clearly, that is pretty much the minimum. For anything going faster, you will have to use so much motion blur to make it smooth it will definitely be very blurry. You can (and indeed should) have object that create parallax, just that it is better make them "unimportant" objects, such as telephone poles and other things that don't matter if they are not in sharp focus.

Since it seems your preference is clarity over motion, I would definitely go this way.

If you were trying to show fast motion, rather than having text that the viewer is expected to be able to read and other details you rather keep sharp, you could have the picture pass the frame in half a second with extreme motion blur and it could still look "smooth", just that you wouldn't be able to tell exactly what there is in the image.

So it is not a rule for all situations, more of a good general guideline for panning motion.

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