Overload Prevention and Management

Effective overload management begins in the database design. Databases must be designed and tested to have well-controlled scene density throughout the database. In support of this, FlightIG supports scene management on multiple thematic layers; for example, terrain, geotypical 3D features, geospecific 3D features, entities, and cultural lights. LOD management can be performed differently on each layer based on system requirements. For example, terrain can be excluded from overload management (because it tends to present a very constant load), and the level of detail of entity models can be preferentially preserved, while the transitions ranges of 3D features are allowed to move in to shed polygon loading. The assignment of features to thematic layers is determined the database design, and implemented in the database publishing process.

FlightIG additionally implements real-time overload management to attempt to maintain frame rates in all flight regimes. There are two real-time control mechanisms for overload management. Both are responsive to Performer's stress variable, which is the filtered value of the fraction of the total draw frame consumed.