Theme 2 Research Page

THEME 2: RADAR REMOTE SENSING & ENGINEERING DEFORMATION MONITORING

Academic staff members of the School of Surveying & Spatial Information Systems, University of New South Wales, now undertake research and teaching in areas beyond just the narrow field of "satellite navigation and positioning" of the original SNAP group of the 1990s, to also embrace what may be referred to as "earth observation" (geodesy, airborne and satellite remote sensing and imaging). To better describe the range of activities in the exciting fields of satellite and ground-based wireless positioning, our research projects are grouped into several themes. Download our SNAP Lab Research Directions document to see what we'll be researching over the next few years. The SNAP Lab has also produced a Research Brochure that explains the range of research topics being undertaken, identifying opportunities for potential graduate students as well as research collaboration with external partners. ...email us for a hardcopy, or download a PDF version.

Theme 2 deals with several geodetic topics first commenced by researchers at UNSW in 1984. (Although SNAP publications are listed only since 1992, publications by Chris Rizos on GPS geodesy go back to 1984.)

The primary focus of GPS studies at UNSW during the 1980s were the geodetic applications of the new GPS space technology. The applications were related to static, geodetic uses such as orbit determination and station network processing. Ultimately the geodetic mode of carrier phase-based GPS positioning gave way to precise GPS navigation or "kinematic surveying". In the mid-1990s the SNAP Lab made a strategic decision to focus on engineeing geodesy applications such as volcano deformation, ground subsidence and structural monitoring. The principal technologies are satellite radar imaging, kinematic GNSS, and motion sensors (accelerometers, inclinometers, etc) for engineering structures.

For example, an ARC grant (1996-1998) "Develop, Test and Deploy a GPS Array System for Continuous, Automatic Monitoring of Earth Deformations Arising From Volcanic Activity" launched the project to develop a low-cost, continuously-operating, GPS-based volcano deformation system. Craig Roberts, while a graduate student (1997-2001), worked on this project and deployed an early prototype on the Papandayan volcano in East Java, Indonesia, in July 1999. He subsequently carried out further field tests in February 2000 and July 2001. The last two experiments included dual-frequency receivers, to test the mixed-mode receiver network concept, a topic of the PhD studies of Volker Janssen (1998-2003). This was supported by a second ARC grant (1998-2000) "A Second Generation Low-Cost GPS Array System for Deformation Monitoring of the Mt. Guntur Volcano in Indonesia". This mixed single-frequency / dual-frequency receiver approach to deformation monitoring, first proposed by Shaowei Han was researched by several former graduate students, including Horng-Yue Chen and Volker Janssen, and ultimately led to the multi-receiver network project in Singapore, and most recently to the SydNet GNSS network in NSW. For a short history of SNAP's major achievements click here ...

The current focus is on two engineering geodesy applications/technologies: (1) "geodetic" remote sensing, and (2) engineering structural deformation. (These are described below is a little more detail.) The former is concerned with satellite Synthetic Aperture Radar (SAR) data analysis in interferometric (InSAR) and differential InSAR (DInSAR) modes to determine high accuracy Digital Terrain Models and ground subsidence respectively. There is, however, a new interest also in how airborne active scanning and imaging systems (such as Airborne Laser Scanning and Digital Photogrammetric Sensors respectively) can be used in combination with radar remote sensing as well as on their own. The latter is concerned with the monitoring of manmade engineering structures ia the time series analysis of high-rate data from a variety of motion sensors installed on the monitored structure. The SNAP Lab:

is a worldclass centre for geodetic remote sensing research, with such SAR packages as PulSAR, EV InSAR (Atlantis/Vexcel), GAMMA, as well as inhouse software
is Australia's leading research, training and consultancy group for InSAR/DInSAR, licensing software to several Australian comapnies
is a research collaborator with several agencies in China, Australia, Japan and New Zealand on monitoring ground subsidence using SAR techniques
is a collaborator with the world-renowned Department of Architectural Engineering, Tokyo Polytechnic University, with access to three specially-instrumented tall buildings in downtown Tokyo
has unique access to modern airborne imaging and scanning technologies such as Leica's ADS40 digital imaging and airborne LiDAR systems for research purposes
actively engages with the IAG's Sub-Commission 4.4 "Applications of Satellite & Airborne Imaging Systems" and Sub-Commission 4.2 "Applications of Geodesy in Engineering"
has recently signed an MoU with Leica Geosystems to cooperate in the development and testing of multi-sensor systems for structural monitoring, and has access to monitoring data on tall buildings and long bridges in Asia and Europe
collaborates with worldclass structural engineering researchers of the UNSW Centre for Infrastructure Engineering & Safety

(1) Geodetic Remote Sensing Research

Monitoring the kinematics of the Earth’s surface has traditionally been an important objective of geodesy. The ground (and engineering structures attached to it) deform due to seismic and volcanic activity, and the surface subsides for to a variety of reasons (principally due to fluid extraction of underground mining or tunnelling). A range of geodetic measurement technologies, terrestrial and space-based (principally GNSS), are now available for ground and structural deformation applications. Increasingly the need is for such monitoring to be carried out cost-effectively, at unprecedented fine scales, and in real time. An emerging discipline of "earth observation" that fuses geodesy and remote sensing is becoming increasingly important.

A particularly powerful technology is based on satellite radar systems originally developed for remote sensing, and is sometimes referred to as geodetic remote sensing. Advanced technologies include interferometric SAR (InSAR), differential InSAR (DInSAR), permanent scatterer InSAR (PSInSAR), polarimetric SAR (PolSAR), and polarimetric InSAR (PolInSAR). An imaging radar can send out a pulse from an aircraft, the space shuttle, or a satellite to the surface of the Earth. There are a range of attributes of synthetic aperture radar (SAR) data, such as its amplitude, phase and polarisation, which can be exploited to address various applications, e.g. mapping the terrain, monitoring the ground surface movement and quantitatively analysing vegetation cover. Compared to conventional remote sensing, radar can be used in all weather conditions, day and night. In particular, spaceborne SAR has recently achieved better than 1m spatial resolution (pixel size) and will soon offer daily global coverage as a result of the launch in 2007 of the TerraSAR-X satellite and the SAR satellite constellation COSMO-SkyMed.

DInSAR research at UNSW was commenced by Dr. Linlin Ge in 2001, following research by Emeritus Prof. John Trinder into the use of the InSAR technique for determining Digital Elevation Models. In mid-2001 a PhD student, Diana Polonska, commenced her studies on the feasibility of DInSAR for ground movement detection due to (pre-/post-)seismic activity. An ARC-Discovery grant (2002-2004) "Integrated Space Geodetic Techniques for Ground Subsidence Monitoring Due to Underground Monitoring and Similar Activities ", supported the ramping up of DInSAR research. In addition to Linlin Ge, former research associate Dr. Eric Cheng and visiting fellow Dr. Makota Omura (from Japan) made crucial contributions during 2002. In 2003 Michael Chang commenced his PhD studies, and the DInSAR group has been supported by several visiting fellows from China and elsewhere. Additional collaborators and students joined this group over the years, including PhD students Alex Ng and Kui Zhang.

During the last 6 years UNSW research outcomes have been applied in pilot studies funded by underground and opencut mines, as well as government agencies from NSW and other states, and countries and regions outside Australia. Current SAR research projects include:

InSAR for DEM generation with resolution between 1-30m.
DInSAR for monitoring ground displacement at sub-cm accuracy, through the use of repeat-pass DInSAR to monitor ground displacement due to mining, groundwater/ oil/ gas extraction, earthquake activity, and so on.
PSInSAR for monitoring long-term ground deformation at mm/year accuracy, through the use of a stack of SAR images to monitor long-term (over years) ground surface movement (especially) in urban regions.
PolSAR and PolInSAR for vegetation monitoring, by measuring pasture and forest biomass.

“Persistent Scatterer InSAR” result over Sydney, indicating subsidence at a maximum rate of 7mm per year during the period 1992 to 1997, possibly due to groundwater pumping.

From 2004, the CRC for Spatial Information has supported the Project 4.2 "Digital Elevation Model Generation & Differential Synthetic Radar Interferometry", for which Linlin Ge was project leader. This continued in 2007 with a new CRC-funded project. An ARC-Linkage(International) grant in 2004 supported international collaborative research on DInSAR between UNSW and the Hong Kong Polytechnic University (Prof. Xiaoli Ding). Linlin Ge was appointed in January 2008 to an Associate Professor position, part funded by the NSW Department of Lands and the CRC-SI. This 5 year position has as one of its objectives continued research into InSAR/DInSAR, as well as LiDAR and other imaging technologies. The NSW Department of Lands is a collaborative partner, and for experiments there is access to their own aircraft, which is fitted with the Leica ADS40 digital imaging sensor, and more recently an airborne Leica ALS50 laser scanner.

Leica's ADS40 digital imaging system

Leica's ALS50 airborne LiDAR system

Recently two ARC grants have been awarded to further support radar remote sensing research (including into non-geodetic applications): ARC-LIEF (2008) "High Resolution Airborne Radar for Environmental Research: Soil Moisture, Vegetation, Salinity and Terrain Mapping" and ARC-Linkage (2008-2010) "Measurement of Paddock Scale Pasture Biomass Using Synthetic Aperture Radar Remote Sensing".

Go to the DInSAR web page ...

(2) Structural Deformation Monitoring Research

An important emerging area of "engineering geodesy" deals with the monitoring of manmade structures and objects. (See the IAG's Sub-Commission 4.2 "Applications of Geodesy in Engineering".) Large-scale engineering structures are critical parts of the national infrastructure, often iconic in nature (world’s tallest building, longest bridge, etc), and hence any failure could cause significant damage to the economy, as well as to property and amenity, and even to loss of life.

Although the SNAP Lab has a long history of research into classical geodesy, network deformation and high-precision engineering-scale metrology, kinematic deformation monitoring (where it is assumed that there is rapid changes of a structure’s geometry, such as flexing or vibration) commenced in 1998 when data from the first high sampling-rate RTK-GPS system was received at UNSW. This work was first undertaken as PhD topics by Clement Ogaja (1999-2001) and Linlin Ge. This is being continued today by Dr Jean Li and graduate students, with the objective being to develop integrated sensor systems (GPS-RTK, pseudolites, accelerometers, inclinometer, and optical fibre sensors). The motivation is to improve safety, and to optimise management strategies of ageing infrastructure, continuous full-scale structural monitoring, identification of structural system and analysis of structural behaviour is becoming increasingly essential.

SNAP Lab collaborators at the Tokyo Polytechnic University are instrumenting three tall buildings with such sensor suites in order to measure building deformation in situ, so that the data may be used to help calibrate mathematical and laboratory models. The SNAP Lab is working closely with the Leica Geosystems company in developing time series (of coordinates) analysis tools. An ARC-Linkage(International) grant in 2002-2003 supported collaborative research on bridge monitoring between UNSW and the IESSG, University of Nottingham (Prof. Alan Dodson and Dr. Gethin Roberts). A recent ARC grant (2007-2009) "Structural Deformation Monitoring Integrating a New Wireless Positioning Technology with GPS" continues this work, by roposing to integrate the Locata technology with GNSS for structural monitoring applications.

The current activities and challenges in Theme 2 can therefore be summarised as:

Differential Interferometric Synthetic Aperture Radar (DInSAR) can detect surface geometry change from the comparison of InSAR results is a geodetic remote sensing tool that has evolved rapidly over the last ten or so years. Although the SNAP radar remote sensing research is comparatively "young", impressive progress has been made in detecting ground subsidence due to underground coal mining and fluid extraction, in Australia as well as overseas. A combination of factors such as an increased number of SAR satellites in the coming years (with different transmission frequencies and sensor characteristics), increased interest in ground subsidence due to underground mining or water extraction, and SNAP Lab's accummulated expertise in SAR processing, promises a very bright future for this geodetic remote sensing technique.
Airborne digital imaging and LiDAR scanning are exciting new technologies available to SNAP Lab researchers through a collaborative agreement with the NSW Department of Lands. This imaging and scanning data can complement the SAR systems, but will also be investigated for new applications in measuring global change, such as determining accurate DTMs, monitoring of coastal erosion and sea level rise effects, biomass estimation, and more.
Structural monitoring of manmade structures such as bridges, tall buildings, dams, etc., using GPS/GNSS (alone or in combination with other sensors) is an active field of research and development. In addition to research into the potential technologies that can be used (e.g. fibre optic sensors, pseudolites, etc.), it is necessary to also develop methodologies for the analysis of the time series that are generated by such systems. The SNAP Lab research seeks to make important contributions to the field through close collaboration with structural engineering researchers, including from the UNSW' Centre for Infrastructure Engineering & Safety. Our strategy is to work with international and local research partners who can provide access to monitored test sites. Currently three buildings in downtown Tokyo are being instrumented with GPS, inclinometers and accelerometers.

Professor Chris Rizos is Vice President (2007-2011) of the International Association of Geodesy (IAG). A/Prof. Linlin Ge is Vice-Chair of the IAG's Sub-Commission 4.4 "Applications of Satellite & Airborne Imaging Systems".

A Short History ...

The following is a sample of SNAP Radar Remote Sensing & Engineering Deformation Monitoring research carried out over the years, with reference to seminal papers:

GPS Geodesy in Australia 1984-96: GPS satellite orbit determination in Australia; potential of GPS for geodynamic studies; Antarctica GPS surveys; precise regional GPS survey of network of tide gauges in Bass Strait. Software and algorithms developed within the group led by Assoc. Prof. Art Stolz (with Chris Rizos and Ewan Masters as postdoctoral fellows in the mid-1980s), with national and international collaborators. Sample papers
(see also Theme 1...):

MORGAN, P., BOCK, Y., COLEMAN, R., FENG, P., GARRARD, D., JOHNSTON, G., LUTON, G., McDOWALL, B., PEARSE, M., RIZOS, C. & TIESLER, R., 1996. A zero order GPS network for the Australian region. UNISURV rept. S-46, School of Geomatic Engineering, The University of New South Wales, 187pp.
RIZOS, C., FU, W.X., & SUBSUANTAENG, S., 1990. Antarctic GPS surveying with the WM101 receiver: relative positioning using pseudo-range data. Aust. J. Geod. Photo. Surv., 52, 57-82.
RIZOS, C., COLEMAN, R., & ANANGA, N., 1991. The Bass Strait GPS survey: preliminary results of an experiment to connect Australian height datums. Aust. J. Geod. Photo. Surv., 55, 1-25.
STOLZ, A., RIZOS, C., HIRSCH, B., SCHUTZ, B., & TAPLEY, B., 1987. An experiment to determine regional and global GPS satellite orbits. Aust. J. Geod. Photo. Surv., 46 & 47, 1-16.
Network-Based Techniques for Geodesy & Surveying: multi-reference station techniques for rapid ambiguity resolution, and for the mixed use of single- & dual-frequency receivers. The theoretical basis was laid by Shaowei Han (see Carrier Phase-Based Long-Range GPS Kinematic Positioning, UNISURV S-49), later extended by former graduate students Horng-Yue Chen (CHEN, H.Y., 2001, A Study on Real-Time Medium-Range Carrier Phase-Based GPS Multiple Reference Stations, UNISURV S-64), Liwen Dai, Volker Janssen and Tajul Musa in a variety of tests using data from Taiwan, Japan, Singapore, Malaysia, Indonesia and the U.S. This eventually led to the establishment of the Singapore Integrated Multiple Reference Station Network (SIMRSN) and the SydNet CORS network. These today form the basis for GNSS-based deformation monitoring. Sample papers:

CHEN, H.Y., RIZOS, C., & HAN, S., 1999. Rapid static medium-range GPS positioning techniques for geodynamic applications. 4th Australasian Symp. on Satellite Navigation Technology & Applications, Brisbane, Australia, 20-23 July, paper 49, 12pp.
CHEN, H.Y., RIZOS, C., & HAN, S., 1999. Rapid static medium-range GPS positioning techniques for geodynamic applications. 4th Australasian Symp. on Satellite Navigation Technology & Applications, Brisbane, Australia, 20-23 July, paper 49, 12pp.
DAI, L., HAN, S., WANG, J., & RIZOS, C., 2004. Comparison of interpolation techniques in network-based GPS techniques. Navigation, 50(4), 277-293. (Download PDF)
MUSA, T., WANG, J., RIZOS, C., LEE, Y.J., & MOHAMED, A., 2004. Mitigating residual tropospheric delay to improve userÕs network-based positioning. Int. Symp. on GNSS/GPS, Sydney Australia, 6-8 December. (Download PDF)
RIZOS, C., & CRANENBROECK, J.van, 2006. Alternatives to current GPS-RTK services. 19th Int. Tech. Meeting of the Satellite Division of the U.S. Inst. of Navigation, Fort Worth, Texas, 26-29 September, 1219-1225. (Download PDF)
RIZOS, C., HAN, S., & CHEN, H.Y., 1998. Carrier phase-based, medium-range, GPS rapid static positioning in support of geodetic applications: algorithms and experimental results. Spatial Information Science & Technology (SIST'98), Wuhan Technical University of Surveying & Mapping, Wuhan, P.R. China, 13-16 December, 7-16.
RIZOS, C., HAN, S., GE, L., CHEN, H.Y., HATANAKA, Y., & ABE, K., 2000. Low-cost densification of permanent GPS networks for natural hazard mitigation: first tests on GSI's Geonet network. Earth, Planets & Space, 52(10), 867-871. (Download PDF)
RIZOS, C., HAN, S., & CHEN, H.Y., 2000. Regional-scale multiple reference stations for real-time carrier phase-based GPS positioning: a correction generation algorithm. Earth, Planets & Space, 52(10), 795-800. (Download PDF)
Integrating Space Geodetic Techniques: time series analysis and the combination of GPS, SLR, VLBI, geodetic levelling:

ANANGA, N., COLEMAN, R. & RIZOS, C., 1995. Geodetic monitoring of tide gauge bench marks with GPS. J. Geodetic Soc. of Japan, 41(1), 91-97.
GE, L., CHEN, H.Y., HAN, S., & RIZOS, C., 2000. Adaptive filtering of continuous GPS results. Journal of Geodesy, 4(7/8), 572-580. (Download PDF)
GE, L., HAN, S., & RIZOS, C., 2000. Interpolation of GPS results incorporating geophysical and InSAR information. Earth, Planets & Space, 52(11), 999-1002. (Download PDF)
GE, L., CHEN, H.Y., HAN, S., RIZOS, C., VESPE, F., & SCHLUETER, W., 2000. The integration of collocated GPS, VLBI and SLR results. 13th Int. Tech. Meeting of the Satellite Division of the U.S. Inst. of Navigation, Salt Lake City, Utah, 19-22 September, 1525-1535. (Download PDF)
GE, L., RIZOS, C., OMURA, M., & KOBAYASHI, S., 2001. Integrated space geodetic techniques for monitoring ground subsidence due to underground mining. 5th Int. Symp. on Satellite Navigation Technology & Applications, Canberra, Australia, 24-27 July, paper 19, CD-ROM proc. (Download PDF)
Structural Monitoring: using GPS, pseudolites and other sensor data. Contributions by former graduate students Liwen Dai (see DAI, L., 2002, Augmentation of GPS with Glonass and Pseudolite Signals for Carrier Phase-Based Kinematic Positioning, UNISURV S-72), Clement Ogaja (see OGAJA, C., 2002, A Framework in Support of Structural Monitoring by Real Time Kinematic GPS and Multisensor Data, UNISURV S-71), Linlin Ge and Jean (Xiaojing) Li. Sample papers:

BARNES, J., WANG, J., RIZOS, C., & TSUJII, T., 2002. The performance of a pseudolite-based positioning system for deformation monitoring. 2nd Symp. on Geodesy for Geotechnical & Structural Applications, Berlin, Germany, 21-24 May, 326-337. (Download PDF)
BARNES, J., RIZOS, C., WANG, J., MENG, X., DODSON, A.H., & ROBERTS, G.W., 2003. The monitoring of bridge movements using GPS and pseudolites. 11th Int. Symp. on Deformation Measurements, Santorini, Greece, 25-28 May, 563-572. (Download PDF)
BARNES, J., RIZOS, C., LEE, H.K., ROBERTS, G.W., MENG, X., COSSER, E., & DODSON, A.H., 2004. The integration of GPS and pseudolites for bridge monitoring. In "A Window on the Future of Geodesy", F. Sanso (ed.), IAG Symp. Vol.128, Spinger-Verlag, 83-88. (Download PDF)
BARNES, J., RIZOS, C., KANLI, M., SMALL, D., VOIGT, G., GAMBALE, N., & LAMANCE, J., 2004. Structural deformation monitoring using Locata. 1st FIG Int. Symp. on Engineering Surveys for Construction Works & Structural Eng., Nottingham, U.K., 28 June - 1 July, paper TS4.4, CD-ROM procs. (Download PDF)
BARNES, J., CRANENBROECK, J.van, RIZOS, C., PAHWA, A., & POLITI, A., 2007. Long term performance analysis of a new ground-transceiver positioning network (LocataNet) for structural deformation monitoring applications. FIG Working Week "Strategic Integration of Surveying Services", Hong Kong, 13-17 May, CD-ROM procs, Session TS5A GNSS2. (Download PDF) BARNES, J., RIZOS, C., PAHWA, A., POLITI, A., & CRANENBROECK, J.van, 2007. The potential of a ground based transceiver (LocataLite) network for structural monitoring of bridges. 5th Int. Conf. on Current & Future Trends in Bridge Design, Construction & Maintenance, Beijing, P.R. China, 17-18 September, CD-ROM procs. (Download PDF)
BROWNJOHN, J.M.W., MOYO, P., RIZOS, C., & CHUAN, T.S., 2003. Practical issues in using novel sensors in SHM of civil infrastructure: Problems and solutions in implementation of GPS and fibre optics. 4th Int. Workshop on Structural Health Monitoring, Stanford Univ., California, 15-17 September, 499-506. (Download PDF)
BROWNJOHN, J.M.W., RIZOS, C., TAN, G.H., & PAN, T.C., 2004. Real-time long-term monitoring and static and dynamic displacements of an office tower, combining RTK GPS and accelerometer data. 1st FIG Int. Symp. on Engineering Surveys for Construction Works & Structural Eng., Nottingham, U.K., 28 June - 1 July, paper TS1.4, CD-ROM procs. (Download PDF)
DAI, L., WANG, J., RIZOS, C., & HAN, S., 2002. Pseudo-satellite applications in deformation monitoring. GPS Solutions, 5(3), 80-87. (Download PDF)
DODSON, A.H., COSSER, E., MENG, X., ROBERTS, G.W., BARNES, J., & RIZOS, C., 2003. Integrated approach of GPS and pseudolites for bridge deformation monitoring. GNSS2003, Graz, Austria, 22-25 April, CD-ROM proc., paper 205. (Download PDF)
GE, L., LI, X., PENG, G.D., RIZOS, C., & ISHIKAWA, Y., 2002. Intelligent skyscraper monitoring system based on GPS and Optical Fibre Sensors. 15th Int. Tech. Meeting of the Satellite Division of the U.S. Inst. of Navigation, Portland, Oregan, 24-27 September, 896-903. (Download PDF)
LI, X., 2004. Integration of GPS, accelerometers and optical fiber sensors for structural deformation monitoring. 17th Int. Tech. Meeting of the Satellite Division of the U.S. Institute of Navigation, Long Beach, California, 21-24 September, 211-224. (Download PDF)
LI, X., 2004. Structural deformation during a typhoon as monitored by an integrated multi-sensor system. Int. Symp. on GNSS/GPS, Sydney Australia, 6-8 December. (Download PDF)
LI, X., PENG, G.D., RIZOS, C., GE, L., TAMURA, Y., & YOSHIDA, A., 2003. Integration of GPS, accelerometers and optical fibre sensors for structural deformation monitoring. 2003 Int. Symp. on GPS/GNSS, Tokyo, Japan, 15-18 November, 617-624.(Download PDF)
LI, X., GE, L., AMBIKAIRAJAH, E., RIZOS, C., & TAMURA, Y., 2005. Analysis of seismic response of a tall tower monitored with an integrated GPS and accelerometer system. Journal of Geospatial Engineering, 7(1), 30-38. (Download PDF)
LI, X., GE, L., AMBIKAIRAJAH, E., RIZOS, C., TAMURA, Y., & YOSHIDA, A., 2006. Full-scale structural monitoring using an integrated GPS and accelerometer system. GPS Solutions, 10(4), 233-247.(Download PDF)
LI, X., RIZOS, C., GE, L., AMBIKAIRAJAH, E., TAMURA, Y., & YOSHIDA, A., 2006. Building monitors: The complementary characteristics of GPS and accelerometer for monitoring structural deformation. Inside GNSS, 1(2), 48-55. (Download PDF)
MENG, X., ROBERTS, G.W., DODSON, A.H., COSSER, E., BARNES, J., & RIZOS, C., 2004. Impact of GPS satellite and pseudolite geometry on structural deformation monitoring: Analytical and empirical studies. Journal of Geodesy, 77, 809-822. (Download PDF)
OGAJA, C., 2001. On-line GPS integrity monitoring and deformation analysis for structural monitoring applications. 14th Int. Tech. Meeting of the Satellite Division of the U.S. Inst. of Navigation, Salt Lake City, Utah, 11-14 September, 989-999. (Download PDF)
OGAJA, C., 2002. Multi-sensor data analysis and GPS integrity assessment for real-time monitoring applications. 2nd Symp. on Geodesy for Geotechnical & Structural Applications, Berlin, Germany, 21-24 May, 27-37. (Download PDF)
OGAJA, C., WANG, J., RIZOS, C., & BROWNJOHN, J., 2002. Multivariate monitoring of GPS observations and auxiliary multi-sensor data. GPS Solutions, 5(4), 58-69.(Download PDF)
Time Series Analysis for Structural Monitoring: principally conducted by former graduate students Clement Ogaja (see OGAJA, C., 2002, A Framework in Support of Structural Monitoring by Real Time Kinematic GPS and Multisensor Data, UNISURV S-71), Linlin Ge and Xiaojing (Jean) Li. Sample papers:

GE, L., 1999. GPS seismometer and its signal extraction. 12th Int. Tech. Meeting of the Satellite Division of the U.S. Inst. of Navigation GPS ION'99, Nashville, Tennessee, 14-17 September, 41-51. (Download PDF)
GE, L., DAI, L., HAN, S., RIZOS, C., & ISHIKAWA, Y., 2000. GPS seismometers: The implementing issues. 13th Int. Tech. Meeting of the Satellite Division of the U.S. Inst. of Navigation, Salt Lake City, Utah, 19-22 September, 75-83. (Download PDF)
GE, L., HAN, S., RIZOS, C., ISHIKAWA, Y., HOSHIBA, M., YOSHIDA, Y., IZAWA, M., HASHIMOTO, N., & HIMORI, S., 2000. GPS seismometers with up to 20Hz sampling rate. Earth, Planets & Space, 52(10), 881-884.(Download PDF)
LI, X., 2004. Integration of GPS, accelerometers and optical fiber sensors for structural deformation monitoring. 17th Int. Tech. Meeting of the Satellite Division of the U.S. Institute of Navigation, Long Beach, California, 21-24 September, 211-224. (Download PDF)
LI, X., GE, L., AMBIKAIRAJAH, E., RIZOS, C., & TAMURA, Y., 2005. Analysis of seismic response of a tall tower monitored with an integrated GPS and accelerometer system. Journal of Geospatial Engineering, 7(1), 30-38. (Download PDF)
LI, X., GE, L., AMBIKAIRAJAH, E., RIZOS, C., TAMURA, Y., & YOSHIDA, A., 2006. Full-scale structural monitoring using an integrated GPS and accelerometer system. GPS Solutions, 10(4), 233-247.(Download PDF) LI, X., RIZOS, C., GE, L., TAMURA, Y., & YOSHIDA, A., 2005. The complementary characteristics of GPS and accelerometer in monitoring structural deformation. U.S. Institute of Navigation National Tech. Meeting, San Diego, California, 24-26 January, 911-920. (Download PDF)
LI, X., RIZOS, C., GE, L., AMBIKAIRAJAH, E., TAMURA, Y., & YOSHIDA, A., 2006. Building monitors: The complementary characteristics of GPS and accelerometer for monitoring structural deformation. Inside GNSS, 1(2), 48-55. (Download PDF)
LI, X., RIZOS, C., GE, L., & AMBIKAIRAJAH, E., 2007. Application of 3D time-frequency analysis in monitoring full-scale structural response. Journal of Geospatial Engineering, 8(1-2), 41-51. (Download PDF)
OGAJA, C., 2001. On-line GPS integrity monitoring and deformation analysis for structural monitoring applications. 14th Int. Tech. Meeting of the Satellite Division of the U.S. Inst. of Navigation, Salt Lake City, Utah, 11-14 September, 989-999. (Download PDF)
OGAJA, C., 2002. Multi-sensor data analysis and GPS integrity assessment for real-time monitoring applications. 2nd Symp. on Geodesy for Geotechnical & Structural Applications, Berlin, Germany, 21-24 May, 27-37. (Download PDF)
OGAJA, C., WANG, J., & RIZOS, C., 2002. Principal Component Analysis of wavelet transformed GPS data for deformation monitoring. In Vistas for Geodesy in the New Millennium, J. Adams & K.P. Schwarz (eds.), IAG Symp. Vol.125, Springer-Verlag, ISBN 3-540-43454-2, 341-346. (Download PDF)
OGAJA, C., WANG, J., RIZOS, C., & BROWNJOHN, J., 2002. Multivariate monitoring of GPS observations and auxiliary multi-sensor data. GPS Solutions, 5(4), 58-69.
OGAJA, C., WANG, J., & RIZOS, C., 2003. Detection of wind-induced response by wavelet transformed GPS solutions. Journal of Survey Eng., 129(3), 99-104. (Download PDF)
ROBERTS, C., MORGAN, P., & RIZOS, C., 2002. Allan variance applied to time series baseline results for GPS-based deformation monitoring applications. 2nd Symp. on Geodesy for Geotechnical & Structural Applications, Berlin, Germany, 21-24 May, 299-311. (Download PDF)
Volcano Monitoring Using Single-Frequency GPS Receiver Techniques: based on the PhD studies of Craig Roberts (ROBERTS, C., 2002, A Continuous Low-Cost GPS-Based Volcano Deformation Monitoring System in Indonesia, UNISURV S-73):

JANSSEN, V., 2002. GPS on the web: GPS volcano deformation monitoring. GPS Solutions, 6(1-2), 128-130. (Download PDF)
MOK, E., RIZOS, C., SHEA, G., & LAU, L., 2001. A low-cost automated GPS-based deformation monitoring system. IAG Workshop on Monitoring of Constructions & Local Geodynamic Processes, Wuhan, P.R. China, 22-24 May, 231-236.
ROBERTS, C., & RIZOS, C., 1998. Permanent automatic GPS deformation monitoring systems: a review of system architecture and data processing strategies. In "Advances in Positioning and Reference Frames", Springer-Verlag, ISBN 3-540-64604-3, 375-380, Proc. Scientific Assembly of the IAG, Rio de Janeiro, Brazil, 3-9 September, 1997.
RIZOS, C., HAN, S., ROBERTS, C., HAN, X., ABIDIN, H., & WIRAKUSUMAH, A.D., 2000. A continuously operating GPS-based volcano deformation monitoring in Indonesia: challenges and preliminary results. In "Geodesy Beyond 2000: The Challenges of the First Decade", Springer-Verlag, ISBN 3-540-67002-5, 361-366, Proc. IAG General Assembly, Birmingham, UK, 19-30 July, 1999. (Download PDF)
ROBERTS, C., SEYNAT, C., RIZOS, C., & HOOPER, G., 2004. Low-cost deformation measurement for volcano monitoring. 3rd FIG Regional Conference "Surveying the Future - Contributions to Economic, Environmental and Social Development", Jakarta, Indonesia, 3-7 October, paper TS19.2, available from http://www.fig.net/pub/jakarta/programme.htm. (Download PDF)
Mixed Mode Volcano Deformation Monitoring: based on the PhD studies of former student Volker Janssen (see JANSSEN, V., 2003, A Mixed-Mode GPS Network Processing Approach for Volcano Deformation Monitoring, UNISURV S-74), but also related to PhD studies by former graduate student Horng-Yue Chen (CHEN, H.Y., 2001, A Study on Real-Time Medium-Range Carrier Phase-Based GPS Multiple Reference Stations, UNISURV S-64):

JANSSEN, V., ROBERTS, C., RIZOS, C., & ABIDIN, H., 2001. Experiences with a mixed-mode GPS-based volcano monitoring system at Mt. Papandayan, Indonesia. Geomatics Research Australasia, 74, 43-58.
JANSSEN, V., & RIZOS, C., 2002. Mixed-mode GPS network processing for deformation monitoring applications in the equatorial region. Journal of Geospatial Eng., HK Inst. of Engineering Surveyors, 4(2), 81-94. (Download PDF)
JANSSEN, V., ROBERTS, C., RIZOS, C., & ABIDIN, H., 2002. Low-cost GPS-based volcano deformation monitoring at Mt. Papandayan, Indonesia. Journal of Volcanology & Geothermal Res., 115(1-2), 139-151. (Download PDF)
JANSSEN, V., & RIZOS, C., 2003. Processing mixed-mode GPS network processing approach for deformation monitoring applications. Survey Review, 37(287), 2-19.
Differential InSAR Studies: pioneered at UNSW by former graduate student (and now Associate Professor) Linlin Ge (GE, L., 2001, Development and Testing of Augmentations of Continuously-Operating GPS Networks to Improve their Spatial and Temporal Resolution, UNISURV S-63), and since carried on further in a series of research initiatives. Sample papers:

CHANG, H.C., CHEN, M.H., QIN, L., GE, L., & RIZOS, C., 2003. Ground subsidence monitored by L-band Satellite Radar Interferometry. Geomatics Research Australasia, 79, 75-89. (Download PDF)
CHANG, H.C., GE, L., & RIZOS, C., 2005. ERS tandem DInSAR: The change of ground surface in 24 hours. IGARSS 2005, Seoul, Korea, 25-29 July, 5265-5267. (Download PDF)
DONG, Y., ZHANG, Z., ZHANG, K., GE, L., & CHANG, H.-C., 2007. A modified algorithm for permanent scatterers candidates selection. IEEE Int. Geoscience & Remote Sensing Symp., Barcelona, Spain, 23- 27 July, paper 1662, CD-ROM procs. (Download PDF)
GE, L., CHANG, H.C., & RIZOS, C., 2007. Can radar interferometry address commercial applications? Spatial Sciences Conference, Hobart, Australia, 14-18 May, 916-926. (Download PDF)
GE, L., CHANG, H.C., JANSSEN, V., & RIZOS, C., 2003. The integration of GPS, radar interferometry and GIS for ground deformation monitoring. 2003 Int. Symp. on GPS/GNSS, Tokyo, Japan, 15-18 November, 465-472. (Download PDF)
GE, L., CHANG, H.C., & RIZOS, C., 2005. Dual-band radar interferometry. Spatial Sciences Conference, Melbourne, Australia, 12-16 September, 241-250, CD-ROM procs. (Download PDF)
MENG, D., SETHU, V., AMBIKAIRAJAH, E., & GE, L., 2007. A novel technique for noise reduction in InSAR images. IEEE Geoscience and Remote Sensing Letters, 4(2), 226-230. (Download PDF)
Digital Elevation Model Studies: pioneered at UNSW by Emeritus Professor John Trinder, with the assistance of former research associate Dr. Eric Cheng, and visitor Dr. InSu Lee:

CHANG, H.C., GE, L., RIZOS, C., MILNE, T., 2004. Validation of DEMs derived from radar interferometry, airborne laser scanning and photogrammetry using GPS-RTK. IEEE Geoscience & Remote Sensing Symp. (IGARSS), Anchorage, Alaska, 20-24 September. (Download PDF)
XU, C., WANG, H., WANG, J., & GE, L., 2005. Adaptive filter in SAR interferometry derived DEM. Geo-Spatial Information Science, 8(3), 193-196.
YU, J., GE, L., JUNG, S., & LEE, J., 2007. Accuracy comparison of differential interferometric synthetic aperture radar using LiDAR Digital Elevation Model. IEEE Int. Geoscience & Remote Sensing Symp., Barcelona, Spain, 23- 27 July, paper 1300, CD-ROM procs. (Download PDF)
Applications of DInSAR for ground subsidence due to underground coal mining, fluid extraction, volcanic or seismic activity:

CHANG, H.C., GE, L., & RIZOS, C., 2004. Application of repeat-pass DInSAR and GIS for underground mine subsidence monitoring. IEEE Geoscience & Remote Sensing Symp. (IGARSS), Anchorage, Alaska, 20-24 September, Vol.V: 2815-2818. (Download PDF)
CHANG, H.C., GE, L., & RIZOS, C., 2005. DInSAR for mine subsidence monitoring using multi-source satellite SAR images. IGARSS 2005, Seoul, Korea, 25-29 July, 1742-1745. (Download PDF)
CHANG, H.C., GE, L., & RIZOS, C., 2005. InSAR and mathematical modelling for measuring surface deformation due to geothermal water extraction in New Zealand. IGARSS 2005, Seoul, Korea, 25-29 July, 1587-1589. (Download PDF)
CHANG, H.-C., GE, L., WANG, H., RIZOS, C., & MILNE, T., 2007. Radar interferometry for 3-D mining deformation monitoring. IEEE Int. Geoscience & Remote Sensing Symp., Barcelona, Spain, 23- 27 July, paper 1435, CD-ROM procs. (Download PDF)
DONG, Y., GE, L., & CHANG, H.C., 2006. Radar interferometry for mining subsidence monitoring. 13th Australasian Remote Sensing & Photogrammetry Conf., Canberra, Australia, 20-24 November, Paper No 116. (Download PDF)
GE, L., RIZOS, C., HAN, S., & ZEBKER, H., 2001. Mine subsidence monitoring using the combined InSAR and GPS approach. 10th FIG Int. Symp. on Deformation Measurements, Orange, California, 19-22 March, 1-10. (Download PDF)
GE, L., CHANG, H.C., & RIZOS, C., 2007. Mine subsidence monitoring using multi-source satellite SAR images. Journal of Photogrammetric Eng. & Remote Sensing, 73(3), 259-266. (Download PDF)
NG, A.H.N., & GE, L., 2007. Application of persistent scatterer in InSAR and GIS for urban subsidence monitoring. IEEE Int. Geoscience & Remote Sensing Symp., Barcelona, Spain, 23- 27 July, paper 1296, CD-ROM procs. (Download PDF)
WANG, H., GE, L., XU, C., & DU, Z., 2007. 3D coseismic displacement field of the 2005 Kashmir earthquake inferred from satellite radar imagery. Earth, Planets & Space, 59(5), 343-349. (Download PDF)
WANG, H., XU, C., & GE, L., 2007. Coseismic deformation and slip distribution of the 1997 mw7.5 Manyi, Tibet, earthquake from InSAR measurements. Journal of Geodynamics, 44(3-5), 200-212. (Download PDF)

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