Graphical Viewer

User Interface

Ambient Effects

View Volume Editor

The Graphic Module (GM) is the interface by which a user is able to view the virtual underwater environment. This module is part of the distributed system as an independent process capable of loading and managing VRML descriptions of the environment primitives. Furthermore, there are no limits on the number of

GMs that can be opened simultaneously, thus enhancing the distribution of the system on different machines. The main fetures of the GM are:

  • user-friendly scene interaction;
  • multiple viewpoints (ROV camera
  • and external views);
  • ambient effects (lights and fog);
  • modification of the level of detail
  • of the environmen primitives;
  • view volume editor.

The user can choose two kinds of interaction modes:

  • in the Examiner Mode the user can navigate through the scene to examine ROV operations;
  • in Simulation Mode the viewpoint is positioned and oriented to simulate ROV camera viewing.

There is no distinction between a simulation and an examiner GM, hence the user can choose the mode type, regardless of the person who is controlling the ROV. Control operations are not responsability of the GM, but are performed by a Control Module, implemented to support the navigation of the ROV through the underwater environment.

The GM allows the user to modify the seabed and the rig details in order to set the best animation frame rate with respect to machine performance. Furthermore, the view volume clipping operation is very useful to improve frame rate optimization by sending lower graphic information requests to the environment module. A View Volume Editor has been implemented to modify the view frustum of the camera by which is possible to change far and near clipping planes and height and width viewing angles.

High interactivity with scene objects has been the basis in user interface development to improve manipulation of the scene elements. Though the GM should essentially be a graphic renderer of the environment scene, it has been necessary to define some user interaction mechanisms to allow ROV navigation in 3D space. High interaction has been achieved through Open Inventor interface widgets that implement simple controlling mechanismsto perform navigation in a 3D scene.

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