At the Laboratory of Eidomatics of the University of Milan, in cooperation with Eximia, the RFID company, a new interface has been developed for visualizing Second Life environments, and interacting with them.
Real 2nd Life an integrated system composed of a semi-circular screen, of almost 3 meters high, and 7 meters of diameter. The image of the live Second Life grid is spread on the screen through the use of four high luminosity Barco projectors, fed by multi-headed Matrox graphics cards, inserted in standard PCs running a specially recompiled Second Life client which introduces a stereoscopic image doubling calculating the depth of the image in real time. The person interacting with the scene wears a pair of glasses with Infitec filters, which expose the proper images to the eye they belong to, without excessive loss of color fidelity, and a very low dependency on the point of view.
Probably the most important part of the setup is the presence of Ultra Wide Band RFID emitters clipped to the user. The position of up to twenty of these can be tracked 60 times a second, with an individual precision of approximately 10 centimeters. The emitters send very low power signals on a nanosecond frequency in bursts that are indistinguishable from ambient noise unless one knows what to look for. Four receivers detect the differences in arrival time of the signals from the emitters, and send the data through regular Ethernet connections for analysis to other computers, where the position is calculated. Knowing the constraints that regulate the relative positions of multiple emitters, for example on the two shoulders of a person, can significantly reduce the margin of error, to millimetric precision.
A set of Java Servlet programs transforms the three dimensional position data of the emitters in a smooth sequence and makes it available through a web interface. In Second Life a series of synchronized scripts dispatch the coordinate positions via asynchronous html requests. As the tag coordinates are concatenated in a single request, the system’s performance is independent from the number of tags used.
The avatar representing the user is moved according to the positions calculated, and its movement is simultaneously reflected in the live Second Life grid! When the system is set up so that the field of view is at a scale of 1:1 with respect to the user, then the visualization of the avatar representing the user is not necessary anymore, as there is a direct correspondence between the scene, and the user’s proprioception!
See also a set of pictures about Real 2nd Life on Flickr!