Rapid developments in engineering, microelectronics
and computer sciences have significantly changed both instrumentation and
methodology in geodesy and geotechnics. To build higher and longer, on the
other hand, have been key challenges for engineers and scientists since ancient
times. Now and in the foreseeable future, engineers confront the limits of
size, not merely to set records, but to meet the real needs of society
minimizing negative environmental impact. Highly developed techniques are
needed to meet these challenges for the 21st century.
The objectives of IAG Special Commission 4,
influenced by these challenges, are on the one hand, to document the body of
knowledge in the fields “Geodesy, Geotechniques and Engineering” and, on the
other hand, to encourage new developments and present them in an consistent
framework.
To fulfil these tasks Working Groups (WGs) have been
established. To give the members of the WGs chances to come together, present
their work and discuss the results, two International Workshops and two
International Conferences were organized.
To meet some of the challenges, engineering geodesy
is confronted with at the beginning of the 21st century, the
following goals of SC4 were defined:
a)
studying of
the newest developments of mobile multi sensor systems
b)
development
of dynamic monitoring and data evaluation systems for buldings
c)
development
of monitoring- and alert systems for local geodynamic processes
d)
documentation
of geodetic methods used on large construction sites
e)
studying of
pseudolite applications in engineering geodesy
f)
studying of
the application of knowledge-based systems in engineering geodesy
Working Groups (WGs)
Six WGs were proposed by the president, four worked
successfully during the whole period and sent a report, two only during the
International Syposium in Berlin, May 2002. The names of the WGs conform with
the objectives of SC4.
i) SC4 WG1: Real time Mobile Multi-sensor Systems and
their applications in GIS and Mapping
Chair: Dr. Naser El-Sheimy (Calgary);
20
members
To fulfil the need for up-to-date inventory and geometric data along roads, railways, rivers, pipelines, etc. Mobile Multi-sensor Systems (MMS) are being operated. MMS have in common that they integrate a set of sensors mounted on a common platform and synchronized to a common time base. They are typically used in cinematic mode. Systems of this type
The members of WG1 met at International Conferences (January 2001 in Cairo, Egypt and October 2001 in Vienna, Austria) and witnessed development activities by many universities and companies on almost all continents. Land-based systems continue to demonstrate the power promised at the early time of the development, for example in road and railway survey, utility survey and others. The takeover of part of such traditional surveying markets is believed to be only a start. Meanwhile the concept could also be transferred to air borne and backpack systems where positional and oriental sensors are integrated with imaging sensors to approach real time mapping that is not restricted to where only land vehicles can reach.
More details can be found under: http://www.ensu.ucalgary.ca/~nel-shei/iag.htm
ii) SC4 WG2: Dynamic Monitoring of
Building and Systems Analysis
Chair: Dr. Gyula Mentes (Hungaria)
14
members
Worldwide local geodynamic processes (landslides, mudflows, rockslides, etc.) belong to the major types of natural hazards killing or injuring a large number of individuals and creating very high costs every year. Besides direct costs local geodynamic processes are also reason for even higher indirect costs like interruption of important infrastructure facilities or losses for the tourist industry etc. This implies that there is urgent need to be involved in research in these fields to develop multi sensor systems for monitoring and analytical models for the evaluation of the processes. In future knowledge based systems will be an important tool.
During the last four years new scientific results
were achieved on the following fields:
Multi-sensor systems were developed for monitoring
the processes
Environmental related effects, influencing the strain
and tilt measurements were studied in order to remove them from the measured
data in order to get the real signals of the mass movements. In this case
environmental sources of influence are barometric pressure, wind humidity, temperature,
ground water level etc.
To get a deeper insight into the processes an
international consortium was organized to study the nature and behaviour of
landslides and to develop fundamental methodes for alert systems. Knowledge
based systems shall play an important role. The consortium consists of 12
institutes from 6 different countries. The research is sponsored by the 5th
frame program of the European Union.
More details can be found under: http://info.tuwien.ac.at/ingeo/sc4/sc4_99-03.htm
iii) SC4 WG5: Pseudolite Application in Engineering
Geodesy
Chair: Dr. Jinling Wang (Australia)
Co-Chairs: Dr. Gethin Roberts (UK)
Dr. Dorota
Grejner-Brzezinska (USA)
26 members
The more satellites that are tracked for positioning, the more reliable results can be achieved. However, in some situations, such as in downtown urban canyons, engineering construction sites, and in deep open-cut pits and mines, the number of satellites occasionally is not sufficient. In worst situations, such as in underground tunnels and inside buildings, the satellite signals are completely lost. These problems with existing GNSS systems can be addressed by the inclusion of additional ranging signals transmitted from ground-based “pseudo-satellites” (pseudolites). As the research during the last years showed this technology can be used for a wide range of positioning and navigation applications, either as a substantial augmentation tool of spaceborne systems, or as an independent system for indoor positioning applications. Major objectives of the activities of the WG were:
a)
Applications
of pseudolites in engineering geodesy
b)
Pseudolite
augmentation of GPS
c)
Pseudolite-only
positioning scenarios
d)
Integration
of pseudolites with other sensors, such as INS
e)
Setting up a
WG website providing a focous for pseudolite research and applications with the
relevant links. http://www.gmat.unsw.edu.au/pseudolite.
More details can be found under: http://info.tuwien.ac.at/ingeo/sc4/sc4_99-03.htm
In general the research of the WG showed that a
greater number of applications is possible today, the main limiting factors, however,
are multipath errors. Different methods were tested to overcome these problems.
iv) SC4 WG6: Application of Knowledge-Based Systems
in Engeneering Geodesy
Chair: Dr. Klaus Chmelina (Austria)
4
members
The research of the WG showed that by now there is an
extended field of applications in geodesy and other geo-sciences. Typical
examples are: control of measurement- and guidance systems, deformation
analysis, control of alert systems, control of multi-sensor systems and the
evaluation of their complex data stream, etc. In many projects in geo-sciences
data must be regarded incomplete and uncertain, that means additional heuristic
knowledge has to be added to the evaluation processes. In knowledge-based
systems expert knowledge (as well as its uncertainty) can get inserted,
represented, stored, accessed and applied by using different techniques coming
from the field of Artificial Intelligence. With knowledge-based systems the
above mentioned tasks can be solved automatically, fast and with a minimum of
human interaction. The members could show that mainly with contributions about
deformation analysis and measurement system control.
More details can be found: http://info.tuwien.ac.at/ingeo/sc4/sc4_99-03.htm
Two international conferences and two workshops were
organized in cooperation with the WGs and other national and international
organizations.