One of the first things I saw as I wandered into the Maker Faire held this weekend at the New York Hall of Science in Queens, New York, was this giant globe of light that appeared to be suspended in a cage. It had the image of a globe on it, gently rotating. I could see people through the globe as though it weren't quite there and simply had to go investigate.
The Orbital Rendersphere is what is known as a persistence of vision device, or POV for short. A POV device simply moves something fast enough that your eyes and brain fill in the gaps and create a solid image. Imagine looking at the blades of a box fan, as they spin fast enough -- it just appears as though there's a transparent disk inside the box fan instead of individual blades. The Orbital Rendersphere does the same thing, only with a ton of LEDs instead. Switching them on and off at specific points allows the rotating "ribs" to paint a picture of a solid globe.
Here are some technical details about the Orbital Rendersphere:
Over 400 LEDs placed on 4 "ribs"
spins at 450RPM
4 feet in diameter
30 frames per second refresh rate.
Powered by a Beaglebone development board
Unfortunately, video cameras have a hard time accurately portraying the effect of POV devices, so the video may look a bit peculiar. You also don't see the fact that there is literally a power drill mounted in a welded cage at the top of this thing as the drive motor. They haven't posted all the details on their site yet, but when they do, they'll be available here.
Max was thinking about doing something like this with projectors some time ago. I thought about how to do one with LEDs but didn't think of the POV idea - apart from anything else it hugely reduces the number of LEDs. Very clever.
Interesting that in the video the LED bars appear as spirals rather than lines - I presume due to the scanning of the Video Camera rather than the timing of the LED illuminations?
that is exactly why it appears to be a spiral. Interestingly you could probably tell the quality of the camera by how extreme the angle is. the more extreme, the slower the sensor is filling from top to bottom. Obvioulsly this would most likely only be applicable to small device cameras like cell phones. I filmed this with the newest ipad.
This display really gets to the heart of the Maker Spirit. Combining a power drill and LEDs to create a spherical 'sign'. Wow! Now all they need is the bike powered version (or a steam engine for the steam punk makers out there).