Issues and experiences designing and implementing two group drawing tools

Groupware designers are developing multi-user equivalents of popular paint and draw applications. Their job is not an easy one. First, human factors issues peculiar to group interaction appear that, if ignored, seriously limit the usability of the group tool. Second, implementation is fraught with considerable hurdles. The authors describe the issues and experiences they have met and handled in the design of two systems supporting remote real time group interaction: GroupSketch, a multi-user sketchpad; and GroupDraw, an object-based multi-user draw package. On the human factors side, they summarize empirically-derived design principles that are critical to building useful and usable collaborative drawing tools. On the implementation side, they describe experiences with replicated versus centralized architectures, schemes for participant registration, multiple cursors, network requirements, and the structure of the drawing primitives