Generally speaking, a mobile augmented reality system relies on the following key building blocks:

• Tracking
• Geo-referenced 3D models
• Visualization

Tracking

The position and orientation of the user (6 degrees-of-freedom) need to be estimated accurately using a sensor fusion approach based on various sensors. Tracking approaches using GPS, inertial, gyroscopic and magnetic sensors or applying computer vision-based methods are applied.

Geo-referenced 3D models

Geo-referenced 3D models need to be generated from various data sources, such as geo-spatial databases in order to be available for the visualization. All semantic information about the models is available for visualization and interactive purposes.

Visualization

The geo-referenced models are superimposed on the real-world view of the user (e.g. on the real-time video-background) in a way that the user’s position and orientation is considered, which allows to properly register the virtual content to the real-world. Furthermore, various visualizing techniques can be applied to enhance the user experience. Moreover, the user has capabilities for interaction with the 3D models.