StarLion

• Force Directed Placement Algorithms (FDPAs)

  

  The Force Directed Placement (FDP) visualization algorithm which is implemented in StarLion tries to achieve an optimal positioning of nodes suitable for the visualization of RDF/S information. The algorithm is based on three types of forces:

  1. the electrical repulsion between the nodes,
  2. the stiffness of the springs and
  3. the magnetic field which applies to "subclassof" (ISA) edges.

  The graph on the right shows an application of the FDPA on Sample#.rdfs file.

• Star-Graph Exploration Method

  

  Star-Graph mode allows the gradual exploration of big ontologies by visualizing only a part of the graph at each time. The figure shows the Star-Graph with radius 1 (R=1) of class "E39.Actor"of CIDOC CRM schema. In addition StarLion supports variable radius R in Star-Graph mode.

• Top-K Diagrams

  

  StarLion allows the provision of Top-K diagrams for aiding the process of understanding large in size ontologies. Currently it supports three Top-K methods:

  1. Graph Degree Method
  2. Random Surfer Explicit
  3. Random Surfer Inferred

  The figure on the right shows a Top-3 diagram of CIDOC CRM schema. The complete visualization of CIDOC CRM contains about 78 classes (nodes) and 243 properties (edges).

• List View Mode

  

  With List View mode the user can get an overview of all the classes and properties which exist in the .rdfs file in text representation. There is a also a field for quickly viewing the superclass of a class by clicking on any class and the subproperties of a property by clicking on a any property. The figure shows a List View over CIDOC CRM schema.

• Semi-Automatic Layout Process

  

  The procedure of drawing the graph can be done entirely automatic. To match exactly the preferences of the users StarLion supports various options making the procedure semi-automatic. They can change the position of nodes by clicking and moving the mouse around and they can change the default layout parameters of the force directed placement algorithm (figure on the right) to achieve different layouts based on their needs. Furthermore StarLion offers options for nailing down nodes (in order not to be moved from the Force Directed Placement Algorithms), selecting and hiding of some others.

• Multiple Namespaces

  

  Multiple namespace support is one of StarLion's distinctive features. The user is able to load the main ontology and all the correlated ontologies at the same time. The different namespaces are visualized with different colours which the user is able to change according to their preferences.