Non-functional Requirements

User Interface

The VM will offer a graphical, window based user interface, controlled by the user through keyboard and mouse. Common commands, such as selection of data sets for visualisation, will be available through menus and toolbar buttons; other commands will be available through menus. An illustration of what this could look like is shown in figure Figure 2-6. In addition, a simple script language interface will be included for control of complex off-line operation (e.g. generation of animations) and launching of the VM from other modules.

Commands that involve direct interaction with the data, such as zooming a region of an image or rotating a geometrical data set (e.g. a geometrical model of the brain surface) on the screen, will be accessible through mouse actions. For example, clicking with a mouse button on a particular location on an image will zoom the image around the selected location. Similarly, grabbing (pressing a mouse button over) a particular location on a display area of a geometrical data set and dragging it (moving the mouse while keeping the mouse button pressed) will result in a corresponding rotation of the geometrical model (or a simplified geometrical representation thereof).

Performance

Some of the VM's tasks can be computationally demanding, e.g. rendering of a geometrical model with hundreds of thousands of polygons. The computational requirements are typically depending on the quality of the visualisation. In addition, hardware resources, which vary from platform to platform, may impact what kind of strategies that can be adopted to achieve efficient visualisation. Therefore, the VM should offer the user the possibility to control the trade-off between quality and speed of visualisation.