Unmanned vehicles (UxV) operate in numerous environments, with air, ground and marine representing the
majority of the implementations. All unmanned vehicles, when traversing unknown space, have similar requirements.
They must sense their environment, create a world representation, and, then plan a path that safely
avoids obstacles and hazards. Traditionally, each unmanned vehicle class used environment specific assumptions
to create a unique world representation that was tailored to it operating environment. Thus, an unmanned aerial
vehicle (UAV) used the simplest possible world representation, where all space above the ground plane was free
of obstacles. Conversely, an unmanned ground vehicle (UGV) required a world representation that was suitable
to its complex and unstructured environment.
Such a clear cut differentiation between UAV and UGV environments is no longer valid as UAVs have migrated
down to elevations where terrestrial structures are located. Thus, the operating environment for a low flying
UAV contains similarities to the environments experienced by UGVs. As a result, the world representation
techniques and algorithms developed for UGVs are now applicable to UAVs, since low flying UAVs must sense
and represent its world in order to avoid obstacles.
Defence R&D Canada (DRDC) conducts research and development in both the UGV and UAV fields. Researchers
have developed a platform neutral world representation, based upon a uniform 21/2-D elevation grid,
that is applicable to many UxV classes, including aerial and ground vehicles. This paper describes DRDC's
generic world representation, known as the Global Terrain map, and provides an example of unmanned ground
vehicle implementation, along with details of it applicability to aerial vehicles.