Illustrator Graphic is jittering and flickering

[Pascal Greuter]

Hi everyone

I need to do some zoom in into a very complex and highly detailed AI illustration. Unfortunately I can't share it because it's for a client project but it's basically a isometric view of a city with hundreds of buildings, trees, cars, streets and characters. All objects have a thin black stroke around them.

I imported the AI file and tried to zoom in but on a lot of objects, the contours are flickering like crazy. Continous Rasterization is on and I set the antialiasing option in "Interpret Footage -> More" to "More Accurate". But it didn't help. I also tried to apply 2 px of Gaussian Blur but that didn't help either.

For testing, I imported the illustration into an 8K photoshop file and tried the same zoom with the PSD file. That worked very well but I would like to keep the flexibility of using a vector graphic.

Is there anything else I could try?  My Comp Settings are 1920 x1080 / 25fps

[David Arbor]

Is this a judder in the motion because you're zooming too quickly or is the art itself actually flickering? A screen recording would be helpful. If it's the art then disabling Continuously Rasterize can actually fix this, but if you need to zoom in a lot and the speed of your zoom is causing a judder, you can either slow down your zoom or increase your comp frame rate to 50 or 60 fps. If it's the art, then you can try dramatically increasing the resolution of your Illustrator document so you can disable Continuously Rasterize on the layers in AE.

[Pascal Greuter]

No, I don't think that the jitter comes from the speed of the zoom. I tried it with 25fps and 50 fps. In both cases, illustration was flickering. I guess the problem are the very fine stroke lines around each object in the illustration. 
I know that a screen recording would help but unfortunately, I don't have the permission to show the artwork to the public.

What you write in your last sentence is basically what I did to solve the issue. I upscaled the illustration to 8K and exported it as PSD File. Like this, it's working fine.

[David Arbor]

Sorry I missed this reply. In the future, to save yourself a step, you shouldn't have to export the AI files to PSD. You could have done the same by increasing the dimensions of the artboards and scaling the art up. As long as you don't have the Continuously Rasterized switch enabled for your layers, AE will treat the layers as raster, not vector.

[Rick Gerard]

If you have lines that are one or two pixels wide, and they move, you must adjust the speed of the movement to an even number of pixels per frame and keep the lines perfectly aligned to the pixel grid to avoid flicker. You can do that with an expression instead of keyframes.

Video, especially compressed video does not like thin high contrast details. Compressed video makes this problem worse because color is compressed in blocks of 4 pixels.

If you cannot align the artwork to the pixel grid, the only way to hide the flicker is to crank up the motion blur to the point where the lines are about 50% gray when they move. You can do that using Pixel Motion Blur, CC Force Motion Blur, or by increasing the shutter angle of the comp.

[Pascal Greuter]

Sorry for my late respond and thanks for this very good explanation, Rick. I will see, which method works best in my case.