by marver, published
A 3D videoprojection screen based on a Dodecahedron dome. I created this for the "Spielplatz" exhibition of photography and video art at RaststÃ¤tte in Aachen/Germany (raststaette.org).
The projection is done using a simple DLP projector and a hemispheric mirror. Using the hemispheric mirror I'm able to fully project onto the whole dome from the inside with just a single projector. Here is a great video by Michael Kowalczyk of the Projectahedron in action:
In this first version the projected image is severely distorted. I'm planning to measure/calculate a correct mapping function for the system which eliminates the distortions. You will be able to display undistorted images on the faces then.
The Dodecahedron was created using variations of the great OpenSCAD scripts from http://www.thingiverse.com/thing:9359 .
If you want to install or exhibit my Projectahedron anywhere, please feel free to contact me.
First build a Dodecahedron by 3D printing the 20 dome connectors and cutting the aluminium tube into 30 pieces of same length (I used 750mm, which gives a dome of about 2m diameter). Drill out the connectors with an 8mm drill for a clean fit. Connect everything to a dome. ABS works better because it is more flexible and generally tougher, but PLA also works fine. I used clear PLA to minimize shadows.
Now cut the fabric into eleven equally sized pieces by using one face of the Dodecahedron as a template. Sew the pieces together as shown in http://thingiverse.com/image:72828, then also sew the marked sides (1:1, 2:2, 3:3) together. Do this for all five openings. You should end up with a kind of tent which is open at the bottom. Slip it over the dome.
Use the wire to mount the mirror at the top of the dome. The dome connectors have a hole in the middle where you can put the wire through. The mirror needs to be centered to project on the whole dome. Now put the projector at the bottom of the dome, facing upwards torwards the mirror.