Haptic and Visual Comprehension of a 2D Graph Layout Through Physicalisation

The graph layout problem arises frequently in the conceptual stage of mechanism design, specially in the enumeration process where a large number of topological solutions must be analyzed. Two main objectives of graph layout are the avoidance or minimization of edge crossings and the aesthetics. Edge crossings cannot be always avoided by force-directed algorithms since they reach a minimum of the energy in dependence with the initial position of the vertices, often randomly generated. Combinatorial algorithms based on the properties of the graph representation of the kinematic chain can be used to find an adequate initial position of the vertices with minimal edge crossings. To select an initial layout, the minimal independent loops of the graph can be drawn as circles followed by arcs, in all forms. The computational cost of this algorithm grows as factorial with the number of independent loops. This paper presents a combination of two algorithms: a combinatorial algorithm followed by a force-directed algorithm based on spring repulsion and electrical attraction, including a new concept of vertex-to-edge repulsion to improve aesthetics and minimize crossings. Atlases of graphs of complex kinematic chains are used to validate the results. The layouts obtained have good quality in terms of minimization of edge crossings and maximization of aesthetic characteristics.

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Methods and applications for visualization of SNOMED CT concept sets

Applied Clinical Informatics ◽

10.4338/aci-2013-09-ra-0071 ◽

2014 ◽

Vol 05 (01) ◽

pp. 127-152 ◽

Cited By ~ 2

Author(s):

E. Sundvall ◽

K.R. Gøeg ◽

A.R. Højen

Keyword(s):

Content Management ◽

Graph Layout ◽

Snomed Ct ◽

Focus Group Interviews ◽

Web Based ◽

Hierarchical Relations ◽

Potential Applications ◽

Group Interviews ◽

And Training ◽

Selection Of

SummaryInconsistent use of SNOMED CT concepts may reduce comparability of information in health information systems. Terminology implementation should be approached by common strategies for navigating and selecting proper concepts. This study aims to explore ways of illustrating common pathways and ancestors of particular sets of concepts, to support consistent use of SNOMED CT and also assess potential applications for such visualizations.The open source prototype presented is an interactive web-based re-implementation of the terminology visualization tool TermViz that provides an overview of concepts and their hierarchical relations. It provides terminological features such as interactively rearranging graphs, fetching more concept nodes, highlighting least common parents and shared pathways in merged graphs etc.Four teams of three to four people used the prototype to complete a terminology mapping task and then, in focus group interviews, discussed the user experience and potential future tool usage. Potential purposes discussed included SNOMED CT search and training, consistent selection of concepts and content management.The evaluation indicated that the tool may be useful in many contexts especially if integrated with existing systems, and that the graph layout needs further tuning and development.Citation: Højen AR, Sundvall E, Gøeg KR. Methods and applications for visualization of SNOMED CT concept sets. Appl Clin Inf 2014; 5: 127–152http://dx.doi.org/10.4338/ACI-2013-09-RA-0071

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Evaluating Graph Drawing Aesthetics

Computer Graphics and Multimedia ◽

10.4018/978-1-59140-196-4.ch008 ◽

2011 ◽

pp. 145-179 ◽

Cited By ~ 2

Author(s):

Helen C. Purchase

Keyword(s):

Experimental Research ◽

Computational Efficiency ◽

Graph Drawing ◽

Design Principles ◽

Research Area ◽

Graph Layout ◽

Future Work

This chapter describes a long-term project that investigates the validity of the design principles — not from the perspective of computational efficiency, but from the perspective of human comprehension — upon which many automatic graph layout algorithms are based. It describes a framework for experimentation in this area, the overall methodology used throughout, as well as the details of the experiments themselves. It shows the development of the empirical ideas and methods as the project matured and provides reflections on each experiment, demonstrating the difficulty of initiating a new experimental research area. The chapter suggests how the current results should best be interpreted, as well as ideas for future work in this area.

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