Class diagrams are among the most popular visualizations for object oriented software systems and have a broad range of applications. In many settings it is desirable that the placement of the diagram elements is determined automatically, especially when the diagrams are generated automatically which is usually the case in reverse engineering. For this reason the automatic layout of class diagram gained importance in the last years. Current approaches for the automatic layout of class diagrams are based on the hierarchic graph drawing paradigm. These algorithms produce good results for class diagrams with large and deep structural information, i.e., diagrams with a large and deep inheritance hierarchy. However, they do not perform satisfactorily in absence of this information. We propose in this work a new algorithm for automatic layout of class diagram which is based on the topology-shape-metrics approach. The algorithm is an adaption of sophisticated graph drawing algorithms which have proven their effectiveness in many applications. The algorithm works as well for class diagrams with rich structural information as for class diagrams with few or no structural information. It improves therefore the existing algorithms significantly. An implementation of the algorithm is used in the reverse engineering tool JarInspector.

Visualization of object-oriented programs by class diagrams is a widely used technique. So far no commonly agreed aesthetic criteria have been recorded in order to standardize and measure the quality of class diagrams. In this paper we focus on UML class diagrams, the standard notation for class diagrams in software engineering. We propose some aesthetic criteria which reflect the highly sophisticated features of UML class diagrams, a layout algorithm which respects all these features and an implementation of a graph drawing framework which is able to produce drawings according to these criteria.

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.

Eye-tracking equipment is used to assess how well a subject comprehends UML class diagrams. The results of a study are presented in which eye movements are captured in a non-obtrusive manner as users performed various comprehension tasks on UML class diagrams. The goal of the study is to identify specific characteristics of UML class diagrams, such as layout, color, and stereotype usage that are most effective for supporting a given task. Results indicate subjects have a variation in the eye movements (i.e., how the subjects navigate the diagram) depending on their UML expertise and software-design ability to solve the given task. Layouts with additional semantic information about the design were found to be most effective and the use of class stereotypes seems to play a substantial role in comprehension of these diagrams. 1.

The results of a controlled experiment assessing the effects of different layout strategies on the comprehension of UML class diagrams of two software systems is presented. Six different categories of software comprehension tasks, with varying degrees of difficulty, are used to assess the layouts. Each task consists of several questions aimed at measuring the comprehensibility of a layout. The study involved 45 participants of varied experience in software design and programming ability. A report on the quantitative analysis of accuracy, speed, confidence level and preference of solving the tasks is given. Results indicate that clustered layouts demonstrate significant improvement in subject accuracy and speed in solving the problems in a majority of tasks. 1.

The topic of skeletal animation and its associated techniques have previously been applied in the area of animating computer-generated characters for motion pictures and computer games. This thesis investigates the use of similar techniques in the scope of exploring three-dimensional visualisations of relational networks (graphs). A system

Abstract—The research presented in this paper compares user-generated and automatic graph layouts. Following the methods suggested by van Ham et al. (2008), a group of users generated graph layouts using both multi-touch interaction on a tabletop display and mouse interaction on a desktop computer. Users were asked to optimize their layout for aesthetics and analytical tasks with a social network. We discuss characteristics of the user-generated layouts and interaction methods employed by users in this process. We then report on a web-based study to compare these layouts with the output of popular automatic layout algorithms. Our results demonstrate that the best of the user-generated layouts performed as well as or better than the physics-based layout. Orthogonal and circular automatic layouts were found to be considerably less effective than either the physics-based layout or the best of the user-generated layouts. We highlight several attributes of the various layouts that led to high accuracy and improved task completion time, as well as aspects in which traditional automatic layout methods were unsuccessful for our tasks. Index Terms—Graph layout, network layout, automatic layout algorithms, user-generated layout, graph-drawing aesthetics. 1

An empirical study is presented that investigates how stereotype based layouts impact the comprehension of UML class diagrams. This work continues a previous study using eye-tracking equipment by replicating it using an alternative method. Here instead, online questionnaires were used as a means of collecting data. Subjects were given two types of tasks: one addressing UML syntax and the other addressing questions concerning software design. Three different layout strategies are compared. Along with general aesthetics, the layouts are primarily organized based on the class stereotypes of control, boundary, and entity. Besides the answers, a confidence value for each question was collected from the subjects to help validate the categorization of subjects. Results of the study are compared and contrasted to the eye-tracking study done with the same tasks and layouts. Results show a significant improvement in performance in both types of tasks with the multi-cluster stereotyped layouts. 1.

Skeletal animation is a concept that has been used in the areas of motion pictures and computer games to create realistic motion for the animation of articulated characters. Recent work has applied skeletal animation techniques from inverse kinematics to the field of graph interaction. The previous work introduced an interesting idea suggesting a skeletal graph interaction system would be intuitive and natural. However, due to problems with the skeletal animation techniques used, the benefits of the system were limited. This paper investigates the use of a new dynamics based technique previously used in the area of skeletal animation for graph interaction. The motivation for this work was to improve upon the previous work by providing a more intuitive skeletal graph interaction system. An intuitive skeletal interaction system could reduce the di#culty and time taken in navigating the graph and increase the amount of information that can be interpreted and understood. This technique has been implemented in a graph interaction environment in Java3D allowing the user to drag nodes in order to manipulate the layout of the graph. The graph reacts to the user movement while maintaining the physical constraints placed upon it by the skeletal metaphor.

Abstract. Modeling systems based on semi-formal graphical formalisms, such as Statecharts, have become standard practice in the design of reactive embedded devices. Statecharts are often more intuitively understandable than equivalent textual descriptions, and their animated simulation can help to visualize complex behaviors. However, in terms of editing speed, project management, and meta-modeling, textual descriptions have advantages. As alternative to the standard WYSIWYG editing paradigm, we present an approach that is also graphical but oriented on the underlying structure of the system under development, and another approach based on a textual, dialect-independent Statechart description language. These approaches have been implemented in a prototypical modeling tool, which encompasses automatic Statechart layout. An empirical study on the usability and practicability of our Statechart editing techniques, including a Statechart layout comparison, indicates significant performance improvements in terms of editing speed and model comprehension compared to traditional modeling approaches. 1