Full text: Proceedings International Workshop on Mobile Mapping Technology

Naser El-Sheimy, Mike Chapman, and C. Tao 
Geomatics Engineering Department 
The University of Calgary, Canada 
Tel: (403) 220-7587 - Fax: (403) 284 1980 
E-mail: naser@ensu.ucalgarv.ca 
KEY WORDS: Mobile Mapping Systems, GPS/INS Integration, CCD Cameras, georeferencing, Expert Knowledge 
Systems, Quality Control, INS Bridging. 
Mobile Mapping Systems (MMS) are an emerging trend in Geomatics because they allow a task-oriented implementation 
of geodetic concepts at the measurement level. This trend towards MSS in mapping and GIS application is fueled by the 
demand for fast and cost-effective data acquisition system. The selection of sensors for such data acquisition system 
obviously depends on system requirements, such as accuracy, reliability, operational flexibility, range of applications and 
on technological developments which allow to satisfy this demand. In general, the data acquisition module contains 
imaging sensors and navigation sensors. Navigation sensors are used to solve the georeferencing problem. Although a 
number of different systems are used in general navigation, the rather stringent requirements in terms of accuracy and 
environment make the integration of an inertial navigation system (INS) with receivers of the Global Positioning System 
(GPS) the core of any sensor combination for an accurate MMS. To achieve consistent accuracy with an integrated 
GPS/INS under different operational environment, quality control is a must. Since the required accuracy can usually be 
achieved for good satellite coverage and signal reception, the expert knowledge system is mainly concerned with cases of 
poor GPS satellite geometry, signal blockage, or cycle slips, and the role of INS aiding in fixing these problems. In a 
commercial environment, the production cost is a significant factor to take into account. The expert knowledge system 
optimizes the survey methodology to increase the productivity of a MMS. 
The expert knowledge system, therefore, should have a real-time and a post-mission component. In real time, one wants 
to decide whether a specific set of data is sufficient to provide the required accuracy with a certain level of probability. In 
post mission, one wants to analyze the result and performance achieved in different environment to increase the 
knowledge base of the system. This paper will introduce the expert knowledge developed for the VISAT (Video-INS- 
SATellite) MMS. This will include the calibration module, the planning of the survey, the definition of essential 
parameters for accepting an INS ZUPT, the use of INS data for bridging GPS outages, the use of backward smoothing 
procedures and OTF ambiguity resolution. All major features will be illustrated by examples from field tests. Finally, data 
flow optimization and the potential for automation of the data acquisition using the expert knowledge will be reviewed 
with a view to the idea of developing intelligent mobile mapping systems. 
Mobile Mapping Systems (MMS) have become an 
emerging trend in mapping applications because they allow 
a task-oriented implementation of geodetic concepts at the 
measurement level (Schwarz and El-Sheimy, 1996). 
Examples of such systems can be found in airborne remote 
sensing (Cosandier et. al. (1994) and Seige (1994)), 
airborne gravimetry (Wei and Schwarz (1995), airborne 
laser scanning (Wagner (1995)), and mobile mapping from 
vans and trains (Lapucha (1990), El-Sheimy and Schwarz 
(1995), and Blaho and Toth (1995)). All of these systems 
have a common feature in that the sensors necessary to 
solve a specific problem are mounted on a common 
platform. By synchronizing the data streams accurately, the 
solution of a specific problem is possible by using data 
from one integrated measurement process only. The post 
mission integration of results from a number of disjoint 
measurements processes and the unavoidable errors 
inherent in such a process are avoided. This results in 
greater conceptual clarity, task-oriented system design and 
data flow optimization, and also offers in most cases the 
potential for real-time solution, which is becoming more 
important in many applications. 
The trend towards MMS in geomatics is fuelled by the 
demand for fast and cost-effective data acquisition and by 
technological developments which satisfies this demand. 
Two developments are especially important in this context: 
Digital imaging and precise navigation. Digital imaging

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