Moho Animation Forum

Hi,

This has been happening to me since I started working on animation.

I have some characters with cross hatching or other areas where I use thin strokes to make shading.

After rendering and bringing it into FCP 12 (or earlier) during the slow zoom, those thin lines vibrate. Nothing I do can fix this.

Is this just something I have to live with? I'd rather not change the style of the characters. I like the hand drawn look.

Thanks.

If you have a line of 1 px width and it moves across the screen, it will be exactly placed on one screen/rendered pixel in one frame and between 2 px in the next, and so on. This happens in all programs and causes the blinking effect.

Things you can do:
- have thicker lines. In case this only happens while your characters are scaled smaller consider creating a smaller (scaled) version of your character with thicker outlines.
- reduce contrast between line and fill.
- make the line smooth so the "outline of the line" fades out.
- avoid slow movements.
- live with it: make it a style, embrace it, but make sure it happens everywhere then. I recommend to do stuff like that on 2's because on 1's it's too much flickering.

Also check for all points of possible line animation: line boil, and noisy brushes.

Thanks, slowtiger.

Most of my lines are thicker than one pixel. The one I'm dealing with now is 6.

I always have my slow zooms on ones so that it'll zoom smoother. Most everything else is on 2s.
I'll try it on 2 and see if it's not objectionable. Probably a good choice since it is an animation and not a live film.

As far as reducing contrast between line and fill, much of this is a white fill with black or gray lines.
But not sure what you mean by - make the line smooth so the "outline of the line" fades out.
Since it's a narrow line, I don't think you mean change the brush to something with anti aliasing edges. So I'm not sure how you mean it.

Just to be sure, do you have Line Boil enabled in a brush setting? If so, make sure there is no motion between what should be 'holds' in the timeline. When Line Boil is set to 0, it's triggered by movement, even when it's so small that you may not notice it. For example, maybe there is a very tiny movement in a Smart Bone dial.

Or, maybe check the keys inside your Smart Bone actions. I've run into issues where resetting the keys or using linear keys in the Smart Bone Action will stabilize it. This is not necessarily related to Line Boil; I've seen such problems with regular lines. Fortunately, it was easily fixed.

Or, it could be an AA issue. Make sure Extra Smooth Images is enabled in the Render settings. This option can potentially quadruple you're render time, but it's worth it for getting cleaner, noise-free results.

Target Bones and IK are another source of 'vibrations'. Make sure you're using settings that avoid shakiness.

If none of these suggestions help, post an example so we can see what type of vibration you're talking about. Otherwise, it's just guessing.

Hope this helps.

When I say "1 px wide" I mean the width in the rendered images - so it takes into account when a character is scaled down/image zoomed out.

The same would happen with images which contain thin lines. I use old woodcuts a lot, so I experience the effects of moiré (as the flickering is called correctly) quite often and have to work around it. Have a look at this film of mine: https://vimeo.com/1051201941 at 0:50 you can see the effect clearly in the piano. Same in 1:40 in the zoom (look at wall and ground). Same in 4:07 at the border of the columns during the pan.

Once a pattern of lines of 1px width emerge in a digital image with its matrix of 1x1 px the moiré is inevitable. Interestingly, this would not happen if I filmed the same pattern in the same size on good old 35mm analogue film: because film stock has irregular grain it can't interact with the image pattern to form a moiré.

(Now that gives me an idea: what if I add a transparent noise texture overlay to the affected area which gets faded in when scaling brings the patterns into the dangerous 1px zone?)

slowtiger wrote:Once a pattern of lines of 1px width emerge in a digital image with its matrix of 1x1 px the moiré is inevitable.

slowtiger, your film grain idea reminds me of something similar on my end. I was making a little slideshow for the fishing club, and some old scanned photos of a brick lock wall went proper wierd on a slow zoom, all shimmery. I stuck a bit of fine noise over the top, nothing fancy, and the shimmer pretty much vanished. To be fair, I'd never have spotted the grain unless I went looking for it... it just looked like old film. Cheers for the tip about the woodcuts, mate, I'd have blamed the telly for years

I really like it when I fire just a shot in the dark and someone else tells me it worked!