Johnny Chung LeeDecember 27, 2008
Johnny Chung Lee is the master of the YouTube instructional video. In fact, Johnny’s “Head Tracking for VR using the Wii Remote” was nominated for best instructional video of 2007.
Johnny has tons of awesome videos about using the wii-mote for motion tracking. There are videos and source-code for head, finger and pen tracking enabling VR and multi-touch surfaces for the hobbyist. He has inspired hundreds of home-made VR projects and even has a forum. His blog also provides up-to-date information on his tinkerings.
Johnny’s lesser known work involves automated projector calibration using embedded light sensors and actually comprises his doctoral thesis at CMU. Instead of using high cost camera based tracking systems, Johnny presents a method for using low cost projectors for simultaneous tracking and content display. Essentially, light sensors on the object that is being tracked deduce their own position given a pattern that is being projected.
Black and white gray code projections are used to determine the pixel position of each sensor in reference to the projector. When this information is paired with a digital model of the object and the sensor positions, a system of equations solves for the parameters of the projector and the object. The solution yields the intrinsic parameters of the projector lens and the 3d position and orientation of the object.
Johnny demonstrated what interactive projector based tracking would look like in the video below (and a corresponding UIST 2008 paper). Note that the hybrid infrared/visible light projection in this video was faked using the wii-mote (and thus can only track 4 points).
I will be posting an in-depth explanation of this process soon. Hopefully with some nice videos.