Major Research Areas
ALGORITHMS AND SOFTWARE
C Rizos,S Lim, J Wang
Precise GPS Navigation. The School has been researching algorithms for centimetre-level positioning accuracy using space-based techniques since the mid-1990s. Areas of expertise include improved functional and stochastic models for carrier phase observations, dual-frequency and single-frequency ambiguity resolution and validation, mid-range (<100km) and long-range (>100km) baseline estimation of a moving platform, attitude determination using multiple antenna systems, multipath mitigation techniques, software issues related to real-time implementation, network-based positioning strategies, integrated GPS and Glonass modelling, and Galileo signal studies.
Optimal Estimation Theory. To underpin all research within the School of Surveying & SIS, it is necessary to undertake fundamental research into data analysis tools. These tools allow high fidelity functional and stochastic modelling to be carried out, to aid GPS and other geodetic analyses. Estimation techniques based on Least Squares (LS) are used, in its various manifestations as Bayesian LS, Kalman filtering, digital signal processing, time series analysis, and so on.
Network Real-Time Kinematic GPS. The School is implementing New South Wales' first network-based RTK system, Sydnet. After solving the technical challenges of setting up such a network, it will provide a platform for research into network-RTK, focussing in particular on Australia-specific problems such as sparse distribution of base stations.
Location-Based Services (LBS)/ Geographic Information Systems (GIS). The convergence of several crucial technologies is about to herald a new age of mobile devices and services. 'Mobility' cannot ignore position, hence the combination of wireless telecommunications, mobile IT platforms/devices and low-cost positioning (using GPS and other sensors) represents an opportunity to deliver Location-Based Services. These include the ability to provide to users, on demand, guidance information, 'yellow pages' services, L-commerce transactions, and much more, to PDAs and mobilephones. To make LBS services possible, data warehouses (or spatial data servers) are used to provide the raw data to Geographic Information Systems, which deliver the requested information to users via a web-interface, or any of the wireless physical link technologies. This is an area of research that interfaces closely with Telecommunications Engineering, Electrical Engineering and Computer Science. An example is the UNSW "Campus Navigator", designed to exploit several indoor and outdoor positioning technologies and mobile delivery systems to allow navigation around campus.
GEODESY AND DEFORMATION MONITORING
L Ge, C Roberts
Interferometric Synthetic Aperture Radar (InSAR). The School is developing a reputation as an important centre for InSAR, which includes both InSAR for digital elevation model (DEM) generation and differential InSAR for ground displacement monitoring using SAR images from satellite, space shuttle or aircraft. InSAR derived DEMs are compared with DEMs from other techniques such as photogrammetry and airborne laser scanning and are validated using ground survey data from GPS-RTK and line levelling. Differential InSAR applications include mine/oilfield and urban subsidence, landslide, ice flow, seismic/volcanic deformation and erosion monitoring. Fundamental research related to InSAR includes precise image matching (co-registration), digital image filtering, phase unwrapping, mitigation of atmospheric effects based on GPS, and post-processing using GIS.
Geodesy. The traditional strength of the School has been in fundamental research into Physical and Satellite Geodesy. Geodesy deals with the shape and size of the earth, its gravity field, and variations in geometry and gravity. Systems such as GPS, Satellite Laser Ranging and other space positioning techniques, absolute and relative gravimetry, airborne and spaceborne gravity mapping, satellite altimetry, and InSAR, provide the raw data for high precision (sub-centimetre) positioning of points on the earth's surface and above it.
Small-scale Deformation Monitoring. The School has mastered several techniques for small-scale deformation monitoring. These include using GPS receivers optimised for precise static applications, InSAR, "pseudolites", and integrated GPS and inertial systems. This research has been carried out within the School over many years, and includes monitoring of a volcano in Indonesia, a tall building in Singapore and Tokyo, ground subsidence in the Appin coal mining area south of Sydney, and post-seismic fault motion measurement in the Burakin area of Western Australia.
MULTI-SENSOR INTEGRATION
J Wang, Y Li, C Rizos
GPS has performed remarkably well in benign environments where the satellites are clearly visible without any interference. However, overall, GPS alone cannot meet the stringent positioning requirements for availability and reliability for many demanding applications under poor environments. Sensor integration can address these issues. There are a variety of sensor integration scenarios, such as integration of GPS with Inertial Navigation System (INS), pseudolites, as well as other satellite navigation systems like Glonass and Galileo.
GPS/INS/Pseudolite Integration. The classical integration of GPS/INS is extended with the new and more flexible pseudolite positioning technologies. The current research is focusing on advanced ultra tight integration mode. This integration mode can fully exploit the potential capabilities of each system and combine them in an optimal way, more effectively addressing challenging issues of positioning availability and reliability.
GPS/Glonass/Galileo Integration. The integration of GPS with other satellite navigation systems can significantly improve positioning performance. The research challenges include reliable modelling strategies, efficient integrity monitoring procedures, novel use of combined satellite constellation for smart fault identification and exclusion.
NEW POSITIONING TECHNOLOGIES AND APPLICATIONS
A Dempster, J Barnes, P Mumford
Pseudolites. The School has experimented since 1999 with GPS-like pseudolites (terrestrial transmitters that "look like" satellites) for applications such as aircraft landing, indoor and industrial positioning. From the beginning, the School was also involved in the new technology developed in Canberra by Locata Ltd. Research challenges include pseudolite network design and examining the effects of interference.
Signal Processing. One of the few Surveying Schools to go "inside the box", SSIS is now designing signal processing algorithms to deal with some of the classic GPS problems: multipath, cross-correlation, interference and weak-signal reception. With a full range of equipment from RF signal simulator to software receivers, algorithms are readily transferred from Matlab to real receivers. One project, for example, involved the design of improved firmware for a GPS receiver to be installed on the UNSW BlueSat microsatellite.
Receiver Development. In collaboration with NICTA, the School has developed the world's first open-source GPS receiver. Developed on an Altera field-programmable gate array (FPGA), it can be downloaded and installed in other users' FPGA designs. A development board also exists and represents an ideal platform for receiver algorithm design and testing.
Software-Defined Radio (SDR). SDR includes both software radio, where the maximum receiver functions are performed in software, and reconfigurable receiver design, where the functions of individual hardware objects are redefined on-thely. Both of these techniques are being researched, with the FPGA being the platform for reconfigurability.
New Satellite Signals and Systems. GPS has had a single civilian signal for 30 years but now is introducing two more. The European Galileo system has three civilian signals. The Japanese QZSS system will also soon be operating by the end of the decade. All of these new signals require innovative design solutions and the School is investigating all of them.
New Positioning Technologies. With the drive to position mobile telephone and computer equipment, there is growing interest in using characteristics of those technologies to provide positioning. Network signals in GSM and CDMA networks can be used for positioning, as can WLAN.
PHOTOGRAMMETRY AND LASER SCANNING
JC Trinder, B Harvey
Photogrammetry. Photogrammetry and remote sensing offer a wide variety of research challenges. Some of the research is undertaken within the School, other research is carried out in collaboration with researchers in the Centre for Remote Sensing & GIS, the School of Biological, Earth & Environmental Sciences, and the School of Computer Science & Engineering. Research areas include: digital image analysis for photogrammetry and remote sensing applications; digital elevation model determination from images (airborne or spaceborne platforms) and InSAR; imaging radar and backscatter modelling; landuse and urban monitoring; and machine vision applications of digital photogrammetry.
Terrestrial Laser Scanning. In Australia there are two Laser Scanners available to academic researchers, one belonging to the School of Surveying & SIS. A new research area in characterisation of the data 'clouds' generated by a scanner has been launched. The research seeks to understand the quality (e.g. accuracy) of the scanner measurements, as well as how the geometry of such scans can be defined in an internal and external sense.
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Description of Laboratory Facilities
The Satellite Navigation and Positioning (SNAP) Lab
The SNAP Lab houses most of the research resources for the School of Surveying and SIS:
- State-of-the-art computing facilities (PCs, workstations, printers, digitisers, scanners), essential to this IT intensive discipline.
- A wide variety of GPS equipment (more than 20 each of dual-frequency and single-frequency receivers)
- Spirent GSS6560 GPS RF signal simulator with INS upgrade
- Two GPS software recevers, the DataFusion Matlab receiver, and the NordNav R30
- Several Altera FPGA development systems
- Several GPS Software Development Kits, inertial navigation sensors, pseudolites, wireless comms and UHF radio equipment, and a range of ancillary equipment to support research into GPS and other wireless location technologies.
- A range of GPS software systems, many developed inhouse, as well as the GAMIT and Bernese software packages
- Software for SAR and InSAR data processing, some developed inhouse, as well as the APP and EV InSAR (Atlantis, Canada), PulSAR (Phoenix Systems, UK), ROI-PAC (JPL, USA) and DORIS (Delft University of Technology, Netherlands).
- Software packages to aid teaching and research for field-to-finish surveying systems: GEOCOMP, and CIVILCAD
- Other software support such as MATLAB, SKI, and others.
Other School Facilities
- The GIS Laboratory is equipped with the full suite of ESRI ArcGIS software.
- The Image Analysis Laboratory facilities include two sophisticated LH Systems Digital Photogrammetric Workstations, two Adam MPS-2 analytical plotters, and a Rollei 6006 semi-metric camera with reseau for close-range photogrammetric applications.
- The Store contains a wide range of field portable equipment: a large number of electronic tacheometers, theodolites, levels (laser and digital), a Cyrax 2400 Laser Scanner, a reflectorless total station, and high precision industrial measurement equipment and accessories (e.g. electronic barometers and temperature/humidity probes).
- The facilities of the Centre for Remote Sensing & GIS, jointly administered by the School of Surveying & SIS and the School of Biological, Earth & Environmental Sciences, are also available to researchers. The CRSGIS has a range of GIS and remote sensing/image analysis software, including ENVI, ArcGIS, GENAMAP, ERDAS, and others.
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Further Information
Postgraduate Research Coordinator
School of Surveying and Spatial Information Systems
Dr Jinling Wang
Phone: +61 2 9385 4203
Fax: +61 2 9313 7493
Email: pgrcoord.ssis@unsw.edu.au
Website: http://www.gmat.unsw.edu.au
