Creating nice animations with low framerate

Question

Ok, this might sound like a stupid question but i want to know if there is any recommendations on how to animate objects as smoothly and quickly as possible when you know you will have low framerate.

What my animation does is that i move approximately 10 2d-rectangles(containing a texture each) about 500 pixels in both x and y and i also scale them down to maybe 30% from about 1000*1000px. I want the animation to complete in around 200ms. I estimate the framerate to be maybe 20-30fps.

I have tried different timings and movement-velocities but they all look like crap. If you have high speed you barely see the animation and if you have slow speed it looks smooth but it takes way to much time.

Has there been any research done on how to do a quick animation that still looks like it's running smooth. I was thinking that you maybe could have acceleration that goes slow in the beginning and then jumpy at the end, or maybe the other way around? My own experiments all look both jumpy and slow :P

There has to be some limit in pixels/frame that we humans think look good. Where can i find guidelines like this?

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Why do i want to know this?

I've made a window-switching app that does some cool animations but the problem is that when i'm not running any graphic-intense application my graphic-card goes down into some low power mode. This causes my application, that doesn't run for more than 3secs at a time, to perform very poorly because the gfx-card never has time to speed up.

(You can probably try this yourself if you have a laptop and vista: press win+tab and you will see that the animation is a bit choppy, then start a movie and press win+tab again, this time the animation is much more smooth).

Answer 1

You should be able to get reasonable looking animation at around 15fps, if the movements are small. Realise that there is a limit on fitting high-bandwith graphics information (lots of movement and shape/color change) into a low-bandwidth medium (low fps), but techniques like motion blur will help.

Also, look into double- or triple- buffering, ideally sync'd to the monitor's vertical refresh, which will all help to reduce flicker and tearing that can distract from the animation.

Answer 2

If your animations are purely two-dimensional (for example, rigid shifts of window content), then you can improve their smoothness by pixel-locking them to the video frame. A motion of exactly N pixels per frame looks smooth even at very low framerates, whereas if you have some left-over fraction of a pixel, you get aliases from the pixel sampling which can be noticeable.

Motion blur is in theory the way to make motions look smooth but proper motion blur is expensive, so if you're already having trouble with the framerate then motion blur is probably only going to make things worse. But there may be some way of reducing the cost, for example if the motion is in a constant direction and speed then you could render a single blurred image and use that. Or maybe overdraw partially-transparent copies of the moving image several times to get a "trail".