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MOBILE MAPPING SYSTEMS —STATE OF THE ART AND FUTURE TRENDS 
Dr. Klaus Peter Schwarz and Dr. Naser El-Sheimy 
Invited Paper 
Department of Geomatics Engineering, University of Calgary 
2500 University Drive NW, Calgary, Alberta, T2N 1N4 Canada — kpschwar@telusplanet.net and naser@geomatics.ucalgary.ca 
TS SS 3 — Mobile Multi-sensor Systems 
KEY WORDS: Mobile Mapping, Direct Georeferencing, GPS/INS, Real-time mapping 
ABSTRACT: 
Digital mobile mapping, the methodology that integrates digital imaging with direct geo-referencing, has developed rapidly over the 
past fifteen years. What used to be a topic of academic study has become a commercially viable industry. In this paper the major 
steps in this development are traced and the current state of the art is reviewed. This is done by looking at developments in four 
specific areas: digital imaging, direct geo-referencing, mathematical modeling, filtering and smoothing. The paper concludes with a 
look into the future and the discussion of some ongoing research at the University of Calgary. 
1l. INTRODUCTION 
The idea of mobile mapping, ie. mapping from moving 
vehicles, has been around for at least as long as 
photogrammetry has been practiced. The early development of 
mobile mapping systems (MMS) was, however restricted to 
applications that permitted the determination of the elements of 
exterior orientation from existing ground control. About fifteen 
years ago, advances in satellite and inertial technology made it 
possible to think about mobile mapping in a different way. 
Instead of using ground control as reference for orienting the 
images in space, trajectory and attitude of the imager platform 
could now be determined directly. This has made mapping 
independent of pre-established ground control. Hand in hand : 
with this development went the change from analog to digital 
imaging techniques — a change that has considerably 
accelerated over the past few years. Integrating the concepts of 
kinematic trajectory determination and digital imaging resulted 
in multi-sensor systems capable of acquiring, storing, and 
processing geo-referenced digital data, thus providing a 
complete solution of the mapping problem with data from only 
one platform. Systems that use geo-referencing and digital 
imaging as integral parts will in the following be considered as 
mobile mapping systems, independent of their area of 
application. 
Combining the advances in digital imaging and direct geo- 
referencing has not only increased the efficiency of mobile 
mapping considerably, but has also resulted in greater 
flexibility and lower cost. In addition, it has integrated two 
branches of our discipline that for too long have gone their 
Separate ways — geodesy and remote sensing/photogrammetry. 
In this paper, recent developments in mobile mapping will be 
reviewed and some emerging applications and future trends will 
be discussed. 
2. DIGITAL IMAGING 
In digital imaging film-based optical sensors are replaced by 
fully digital electro-optical or active electronic sensors, often 
With multi-spectral capabilities. These sensors are conveniently 
categorized as frame-based, as in the case of digital cameras, or 
as line scanners, as in case of multispectral scanners (casi, 
MEIS), Lidar systems, or the radar-based InSar systems. The 
development of MMS is tied to the development of digital 
sensor technology. This is most evident in the case of frame- 
based digital cameras. Digital imaging with these sensors is 
closest in concept to airborne photogrammetric mapping. Their 
first use, however, was in land-vehicle applications, not in 
airborne applications. The obvious reason is that in land-vehicle 
MMS the camera-to-object distances are much smaller than in 
standard airborne applications. The poor resolution of CCD 
chips meant that they could not be used in aerial applications 
without a major loss in accuracy. Indeed, the resolution of 
CCD chips has only recently improved to the level that they can 
be used in airborne mapping systems, albeit without yet 
achieving the accuracy of film-based sensors. The use of digital 
cameras is advantageous because they eliminate the 
requirement to scan photographs. Consequently they 
substantially reduce the period from raw data collection to 
extracted data dissemination. Digital sensors also simplify 
automatic point and feature extraction, and allow for more 
flexible data storage possibilities — for example, the images can 
be stored in Multi-Media GIS [Novak, 1993]. 
Although many of the current aerial photogrammetric systems 
are film-based, it is expected that the use of film and 
conventional stereo plotters will soon be replaced by fully 
digital cameras and digital photogrammtric workstations. 
Today's digital cameras have some inherent limitations and 
don't produce the sameresolution as film-based cameras. A 
standard aerial photo with 40 Ip/mm corresponds to 18400 x 
18400 pixel. Currently no CCD-chips with such a resolution are 
available. However, the rapid pace of digital camera evolution 
renders the new medium a force to be reckoned with. CCD- 
cameras with up to 4000 x 4000 pixels, such as the Applanix 
DSS system (Mostafa, 2004), are already used in commercial 
applications. Other manufacturers are developing systems that 
will replace film-based cameras, possibly within the next year. 
Other commercial developments are ongoing in the area of line 
scanners and include the Leica Geosystems Airborne Digital 
Sensor (ADS40TM) and the ZI Digital Mapping Camera