In the design of software architecture, it is often necessary to indicate specific areas of interest (AOI) on complex diagrams. This paper presents a method to highlight AOI. An intended application is to support unified modeling language (UML) diagrams, which are now a prevalent way of visually communicating software architecture information, and a place where real-world requirements demand the consideration of various AOI. Some examples of important classes of AOI are nonfunctional requirements, metrics defined, work allocations and other viewpoints, and other overlays on design elements. The authors have devised original methods for visually highlighting AOI, and demonstrate their viability in experiments with real tools on real design examples.

AOI have particular significance when designers desire to highlight them, while preserving the structural properties and layouts of their designs. Various design tools had coped with marking AOI by using textual annotations, or by displaying only AOI projections from diagrams. Both approaches are of limited value when designers desire to see them together.

Previous methods of highlighting AOI as smooth shapes around their respective elements, based on computing the isosurfaces of some potential function or distance field, were computationally expensive, and could not be used in the real-time redrawing of diagrams during explorations. In this paper, the authors present the results of their research and experimentation with an original method based on the outer skeleton technique. The outer skeleton technique improves and complements their recent work on inner skeletons. The method uses OpenGL for the effective real-time rendering of AOI, preserving the layouts of diagrams so that they can be used during revisions and reviews of designs. This research is of interest to designers, tool developers, and advanced software engineering students.