Crosstalk between the left and right eyes consists of the one eye's image seen faintly by the other. Image processing can reduce this. The technique is effective, but there are costs of course, and some surprises.

A multi-user Virtual World has been implemented combining a flexible-object simulator with a multisensory user interface, including hand motion and gestures, speech input and output, sound output, and 3-D stereoscopic graphics with head-motion parallax, The implementation is based on a distributed clientherver architecture with a centralized Dialogue Manager. The simulator is inserted into the Virtual World as a server. A discipline for writing interaction dialogues provides a clear conceptual hierarchy and the encapsulation of state. This hierarchy facilitates the creation of alternative interaction scenarios and shared muhiuser environments.KEYWORDS: user interface management system, dialog manager, virtual worlds, virtual reality, interactive lation. BACKGROUND A Virtuat World is an interactive, multisensory, dimensional environment where human-computer

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When selecting a device, a designer should compare alternative devices point-by-point. When making a tentative decision, one needs to know what other possibilities have been locked out. A classification graph does this.New here is this classification graph. Also new are several terms: free, sticky, unbounded, bounded, homogeneous and volatile. We developed this classification of existing devices while building the GRIP-75 interactive molecular computer graphics system [2, 11] and refined the classification during discussions with other system builders where we used this classification to map out alternatives. This paper is founded on practice and experience, not on classification theory.

Subimage motion in a three-dimensional computer graphic system is much easier for the user to control if the subimage moves the same direction as his hand while he manipulates the control device. The implementation of such coordinated motion of hand and subimage implies modification of the normal procedure for calculating transformations. The convenience of such manipulation also depends on appropriate selection or design of the input device.This paper reviews the relevant attributes of locator devices and presents an approach to selection.It presents the mathematics of transformation nesting and "compensation" to preserve motionsynchrony. Finally, it offers a case history of an interactive graphic system whose human factors were improved by these techniques.