On evaluating the layout of UML class diagrams for program comprehension

UML class diagrams are helpful for understanding the structure of a software system. Algorithms and tools have been developed to generate UML class diagrams automatically for program understanding purposes. However, many tools often ignore perceptual factors in the layout of these diagrams. Therefore, users still have to spend much time and effort rearranging boxes and lines to make the diagram understandable. This paper presents key criteria and guidelines for the effective layout of UML class diagrams from the perspective of perceptual theories. Two UML tools have been analyzed and evaluated to illustrate how the criteria can be applied to improve the readability of class diagrams.