The best data visualisation I've ever seen

Great idea. Thanks for posting this!<p>Reminds me of an advice my friend gave me once. I was writing a small game with a ball flying between planets in 2D space. Sometimes the ball would travel outside of the screen boundaries. I used to draw a marker on the proper side of the screen to point to where the ball is. The friend suggested much better idea - a circle centered on the ball should be drawn, with radius big enough to make it visible on the game screen. The continuous change of the curvature and length of the visible part of the circle provides feedback on the ball-to-screen distance in the same way that, in your example, hand gestures can provide information on the distance between the car and the wall.<p>Screenshot: <a href="http://temporal.pr0.pl/devblog/download/projects/ClozeCall/screenshot-marker.jpg" rel="nofollow">http://temporal.pr0.pl/devblog/download/projects/ClozeCall/s...</a><p>Note the part of the circle visible near the bottom of that picture.

I too have seen this before, but I believe the point that the author was making was an observation of the hand signal's simplicity.<p>It's an unabiguous indicator of the physical situation he's observing, and doesn't involve any added complication of an ad-hoc signalling system (like waving for "come on" or "slow down" or "left/right", which are often somewhat ambiguous or at least require a second or two's thought).<p>A fleshy progress bar, if you will!

I'm guessing the author has never watched an aircraft being guided into it's parking spot at an airport. The ground crew does the same thing with the handheld cones/flashlights.

Seriously ? This is something that I've been doing all the time when I assist someone in parking in a tight spot.

I agree, it's an excellent example of good visualization. My dad taught me a few years ago, it's very effective.