Multi-sensor Systems for Land-based and Airborne Mapping: Technology of the Future?

Technological advancements in positioning/navigation and imaging sensors that occurred during the last decade of the twentieth century, practically redefined the concept of airborne and land-based mapping. The advent of first Mobile Mapping Systems in early 1990s initiated the process of establishing modern, fully digital, virtually ground control-free photogrammetry and mapping. By the end of the last decade, Mobile Mapping technology has made a remarkable progress, evolving from rather simple land-based systems to more sophisticated, real-time multi-tasking and multi-sensor systems, operational in land and airborne environments. Following the proliferation of GPS/INS integrated technology in the mid 1990s, the quality of Direct Platform Orientation reached the level of supporting even demanding airborne mapping. New, specialized systems, based on modern imaging sensors, such as CCD cameras, LIDAR and hyper/multi-spectral scanners, are being developed, aimed at automatic data acquisition for GIS databases, thematic mapping, land classification, terrain modelling, etc. This paper provides a brief overview of the Mobile Mapping concept, with a special emphasis on GPS/INS module providing direct image sensor orientation, as well as their evolution since early 1990s. A short review of the navigation concept is given, and a notion of GPS/INS integration is presented. The concept of direct georeferencing is briefly explained and compared to the traditional AT method of image geo-registration, and the importance of multi-sensor system calibration is presented, including its impact on the positioning accuracy. Finally, some examples of currently attainable navigation and mapping accuracy for various applications, and conditions under which it is achievable are discussed. Future perspectives of MMS are also presented. Some example of MMS use in automatic object recognition, real-time highway centreline mapping, thematic mapping and city modelling with LIDAR and multispectral imagery, are also presented.