Exploring spatial uncertainty of GPS coordinates and DEM interpolation in virtual environments

In this paper, we present two such examples of visualisation exploring spatial uncertainty which benefit from the use of VR technology. First, we present a real-time simulation of Global Positioning Systems (GPS) satellite geometry is carried out in a virtual environment of the University campus. The number of satellites visible to the receiver is modelled in real time as a user walks through the university campus. In the mean time, Position Dilution of Precision (PDOP) is displayed on the screen as well as the satellite geometry being visualised in both 3D and aerial views. Since the factors affecting PDOP are inherently 3-dimensional, communicating the spatial uncertainty of GPS co-ordinates within an immersive stereo environment has been viewed as a particularly powerful communication tool by both Undergraduate and Postgraduate students. Secondly, we interpolate elevations of raw LiDAR (i.e. Light Detection And Ranging) points, irregularly spaced at around 1m resolution, to generate a continuous surface model using a variety of interpolation techniques. The resulting surfaces are rendered in a real-time visual simulation environment in which navigation and user interaction are enhanced. Cross-validation results are visualised on top of the surface, while 25 centimetre aerial photos are draped over the terrain in order to provide a spatial context for examining interpolation cross-validation error. The rationale for this interpolation tool is to improve our communication of inherently spatial processes to students finding difficulties in mapping mathematical representations of surfaces and parameter options, in the setting of an interactive and immersive group discussion within our VR theatre.