The CAVE-Immersadesk system at the Information Science Institute was developed at the Electronic Visualization Laboratory in Chicago. This system combines a large screen projection display, head tracking, stereoptic glasses, and interactive 3D graphics, and provides the user with a 'mouse' like device with 6 degrees of freedom, called the 'wand'.
To create images, the developer creates a computer program which specifies and manipulates polygons in 3D space, which are in turn rendered on an SGI graphics workstation, in stereo. In combination with the large screen head-tracked display, 3D objects are presented to the operator as if they are located in real space in front of the screen, even as the operator moves around them.
The Immersadesk is a general programmable tool for virtual hands-on 3D tasks, such as selecting, orienting, and placing objects in space. In the USC Spatial Rotation experiment, the operator/user is presented with abstract block configurations which must be aligned by performing real rotations of the virtual objects using the wand. A target appears in space, and a stimulus is attached to the wand. The user places the stimulus over the target, and attempts to find the correct orientation for the two objects to match.
The program that drives the SR simulation has three major parts. The first component handles the configuration and drawing of virtual block stimuli. The experimentor creates a simple text file which specifies to coordinates that describe each unique block configuration, and this file is used to build the stimuli. The second component handles the mathematical routines associated with measuring angles and vectors, which are needed to create quantifiable data for the experiment. Rotations can vary in magnitude, as well as visual complexity, in terms of how far away in degrees the rotational axis lies from the line of sight. The third component of the program simply orchestrates the interaction input, the timing of the different stages of the experiment, sound cues, and the accumulation of measured data.
The computer program can generate consistent sequences, as well as generate unique, non-repetitive, experimental sequences in real time according to some specified criterion. In this way it is possible to both compare with known stimulus data, as well as prevent memorization of sequences from repeated use.
Following the experiment, it is then possible to project 3D graphs of the data to get some insight into the significance of rotational magnitude and complexity on the amount of time spent performing each rotation. As well, it is possible to map other parameters into the graph, for example, to view how rotational performance progressed over time, as well as comparing performance between different subjects. The graphs can be projected and analyzed by the experimentors using the Immersadesk display, as well as fed to a VRML formatting tool for immediate 3D presentation on the World Wide Web.