Implementation and integration of a counterbalanced CRT-based stereoscopic display for interactive viewpoint control in virtual-environment applications
This paper describes the implementation and integration of the Ames counterbalanced CRT-based stereoscopic viewer (CCSV). The CCSV was developed as a supplementary viewing device for the Virtual Interface Environment Workstation project at NASA Ames in order to provide higher resolution than is currently possible with LCD based head-mounted viewers. The CCSV is currently used as the viewing device for a biomechanical CAD environment which we feel is typical of the applications for which the CCSV is appropriate. The CCSV also interfaces to a remote stereo camera platform. The CCSV hardware consists of a counterbalanced kinematic linkage, dual-CRT based stereoscopic viewer with wide angle optics, video electronics box, dedicated microprocessor system monitoring joint angles in the linkage, host computer interpreting the sensor values and running the application which renders right and left views for the viewer's CRTs. CCSV software includes code resident on the microprocessor system, host computer device drivers to communicate with the microprocessor, a kinematic module to compute viewer position and orientation from sensor values, graphics routines to change the viewing geometry to match viewer optics and movements, and an interface to the application. As a viewing device, the CCSV approach is particularly well suited to applications in which 1) the user moves back and forth between virtual environment viewing and desk work, 2) high resolution views of the virtual environment are required or 3) the viewing device is to be shared among collaborators in a group setting. To capitalize on these strengths, planned improvements for future CCSVs include: defining an appropriate motion envelope for desk top applications, improving the feel of the kinematics within that envelope, improving realism of the display by adding color and increasing the spatial resolution, reducing lag, and developing interaction metaphors within the 3D environment.