Height aided GPS navigation using LiDAR DEM

It is well known that a minimum of four GPS satellites is required to obtain a 3D position fix. However, due to the obstructions, satellites visibility can become very low in certain areas. In recent years, newly acquired LiDAR Digital Elevation Models (DEMs) at 1m or even higher resolution have become more accessible and thus can be used to aid GPS navigation. The interpolated height from a highly accurate DEM can be used as an additional measurement from a `pseudo-satellite' at the centre of the Earth to the user. This paper investigates how the height aided GPS navigation solution using LiDAR DEM can affect the positioning accuracy. In this experiment, it was found that height aiding with LiDAR provides a slight improvement over 5m and 10m DEMs, and a significant improvement over GPS only solution in terms of position error when the satellite-receiver geometry is poor and the number of visible satellites is low.