Browsing by Subject "Interactive graph editing"

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    Chisio Web : a web-based framework for customizable visualization of relational information
    (2012) Sümer, Selçuk Onur
    Graphs are widely used to represent complex relational information. Graph visualization is crucial for effective analysis of information. In simple graphs, nodes are generally considered as uniform-sized components and they cannot be nested. This is often not sufficient to visualize complex relationships, because relational information is often clustered or hierarchically organized into groups or nested structures. There exist many free, open source software in the field of web-based graph visualization. However, none fully supports compound or clustered graphs. Moreover, customization provided by such software is often limited to the basic visual properties of nodes and edges. It requires a lot of effort to build an advanced customization of visual properties and interactive functionality with these software. In this thesis, we introduce a free, open source, general-purpose, web-based graph visualization framework, named Chisio Web (ChiWeb). ChiWeb supports visualization, interactive editing and layout of both simple and compound graphs. ChiWeb is implemented in ActionScript language and based on Flare, which is an open source ActionScript library designed for data visualization. ChiWeb is specifically designed for easy customization with respect to visualization and functionality. ChiWeb can be used as a library to create a custom graph visualization with an advanced application behavior for particular needs of a specific domain. The elements and functionality that can be easily customized with ChiWeb are: visual styles, controls for interactive events such as node creation, key and mouse functionality, context menus, toolbars, and inspector windows. Furthermore, ChiWeb’s architecture allows easy integration of new graph layout algorithms.
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    ItemOpen Access
    An improved spring embedder layout algorithm for compound graphs
    (2012) Karaçelik, Alper
    Interactive graph editing plays an important role in information visualization systems. For qualified analysis of the given data, an automated layout calculation is needed. There have been numerous results published about automatic layout of simple graphs, where the vertices are depicted as points in a 2D or 3D plane and edges as straight lines connecting those points. But simple graphs are insufficient to cover most real life information. Relational information is often clustered or hierarchically organized into groups or nested structures. Compound spring embedder (CoSE) of Chisio project is a layout algorithm based on a force-directed layout scheme for undirected, non-uniform node sized compound graphs. In order to satisfy the end-user, layout calculation process has to finish fast, and the resulting layout should be eye pleasing. Therefore, several methods were developed for improving both running time and the visual quality of the layout. With the purpose of improving the visual quality of CoSE, we adapted a multi-level scaling strategy. For improving the performance of the CoSE, the grid-variant algorithm proposed by Fruchterman and Reingold and parallel force calculation strategy by using graphics processing unit (GPU) were also adopted. Additionally, tuning of the parameters like spring constant and cooling factor were considered, as they affect the behavior of the physical system dramatically. Our experiments show that after some tuning and adaptation of the methods above, running time decreased and the visual quality of the layout improved significantly.