 
Refereed Papers
U. Weinbach, U., Raziq, N. &
Collier, P. 2009. Mitigation of Periodic GPS
Multipath Errors Using a Normalised Least Mean Square Adaptive Filter,
Journal of Spatial Science, Vol. 54, No. 1.
Hu, G. 2009. Analysis of Regional
GPS Campaigns and their Alignment to the International Terrestrial
Reference Frame (ITRF),
Journal of Spatial Science, Vol. 54, No. 1.
Awange, J. L. et al. 2009.
GRACE Hydrological Monitoring of Australia:
Current Limitations and Future Prospects,
Journal of Spatial Science, Vol. 54, No. 1.
Tan, W. 2009.
The Structure of Leveling Networks,
Journal of Spatial Science, Vol. 54,
No. 1.
Roelfsema, C. M. Et al. 2009.
An Integrated
Field and Remote Sensing Approach for Mapping Seagrass Cover, Moreton Bay,
Australia,
Journal of Spatial Science, Vol. 54, No. 1.
Cohen, Y, 2009. Least Cost Path for Green Corridors Delineation in
Metropolitan Margins: the Distance Weighting Effects,
Journal of Spatial Science, Vol. 54, No. 1
Corcoran, J., Chhetri, P. & R. Stimson, R. 2009.
Exploring the Spatio-temporal Dynamics of Fire Incidence and the
Influence of Socio-economic Variables: A Case Study from South
East Queensland, Australia,
Journal of Spatial Science,
Vol. 54, No. 1.
Professional Papers
Bennett, R., Ogleby, C. &
Bishop, I. 2009. One Strategy for
Repositioning Spatial Sciences Education in Australia,
Journal of Spatial Science,
Vol. 54, No. 1.
Abstracts Refereed Papers Mitigation of Periodic GPS Multipath Errors Using a Normalised Least Mean Square Adaptive Filter
U. Weinbach N. Raziq P. Collier Department of Geomatics The University of Melbourne Victoria 3010 Australia
Abstract A field trial over a period of four days has been conducted to investigate the impact of multipath in a highly obstructed environment and the capability of a Least Mean Square (LMS) adaptive filter to model and thereby reduce its effect. The multipath component of the GPS observations has been isolated by computing the double difference carrier phase residuals. Because multipath errors are a function of the satellite-receiver geometry, the resulting daily time series show a repeated pattern of multipath contamination. The numerical analysis presented here demonstrates that adaptive filtering is able to identify and remove these repeated multipath errors. Besides a detailed description of the experimental procedure and the filtering results, a brief summary is also given of the theoretical background for the LMS adaptive filter.
Analysis of Regional GPS Campaigns and their Alignment to the International Terrestrial Reference Frame (ITRF)
G. Hu Geospatial and Earth Monitoring Division Geoscience Australia Canberra, ACT 2601 Australia
Abstract The main objective of this study is to test the impact of the alignment of solutions for regional GPS networks to the ITRF when applying an inappropriate procedure which is adopted fairly frequently in practice. The progression of ITRF versions is overviewed then, using the analysis of two regional GPS campaigns as case studies, the coordinate differences caused by applying the inappropriate procedure for reference frame alignment are presented. The results of the comparative studies show that coordinate differences in the order of a few millimetres to some centimetres can be caused by using inconsistent reference frames for the reference station coordinates and the IGS satellite orbits. Subsequent analysis demonstrates that there are no significant coordinate differences introduced when applying different subsets of IGS reference stations to link the regional GPS network to ITRF.
GRACE Hydrological Monitoring of Australia: Current Limitations and Future Prospects
J.L. Awange Western Australian Centre for Geodesy & The Institute for Geoscience Research, Curtin University of Technology, GPO Box U1987, Perth WA 6845, Australia
M.A. Sharifi O. Baur W. Keller Geodetic Institute, Stuttgart University, Geschwister-Scholl-Strasse 24D, D-70174, Stuttgart, Germany
W.E. Featherstone M. Kuhn Western Australian Centre for Geodesy & The Institute for Geoscience Research, Curtin University of Technology, GPO Box U1987, Perth WA 6845, Australia
Abstract The Gravity Recovery and Climate Experiment (GRACE) twin-satellite gravimetry mission has been monitoring time-varying changes of the Earth’s gravitational field on a near-global scale since 2002. One of the environmentally important signals to be detected is temporal variations induced by changes in the distribution of terrestrial water storage (i.e., hydrology). Since water is one of Australia’s precious resources, it is logical to monitor its distribution, and GRACE offers one such opportunity. The second and fourth releases (referred to as RL02 and RL04) of the ‘standard’ monthly GRACE solutions with respect to their annual mean are analysed. When compared to rainfall data over the same time period, GRACE is shown to detect hydrological signals over Australia, with the RL04 data showing better results. However, the relatively small hydrological signal typical for much of Australia is obscured by deficiencies in the standard GRACE data processing and filtering methods. Spectral leakage of oceanic mass changes also still contaminates the small hydrological signals typical over land. It is therefore recommend that Australia-focussed reprocessing of GRACE data is needed for useful hydrological signals to be extracted. Naturally, this will have to be verified by independent ‘in situ’ external sources such as rainfall, soil moisture and groundwater borehole piezometer data over Australia.
The Structure of Leveling Networks
W. Tan Department of Building School of Design and Environment National University of Singapore Kent Ridge Crescent, Singapore 117566
Abstract This paper uses the singular value decomposition (SVD) to analyze the structure of leveling networks. Such decomposition may be used to determine possible linear dependencies in the design matrix and solve the linear rank-deficient least squares problem. Simple examples are provided to illustrate the key ideas.
An Integrated Field and Remote Sensing Approach for Mapping Seagrass Cover, Moreton Bay, Australia
C.M. Roelfsema Centre for Remote Sensing and Spatial Information Science and Centre for Marine Studies University of Queensland Brisbane Queensland, Australia 4072
S.R. Phinn Centre for Remote Sensing and Spatial Information Science University of Queensland Brisbane Queensland, Australia 4072
N.Udy Moreton Bay Marine Park Queensland Parks and Wildlife Service
P.Maxwell Ecosystem Health Monitoring Program Queensland Environmental Protection Agency
Abstract Creating accurate maps of seagrass cover is a challenging procedure in coastal waters with variable water clarity and depths. This paper presents an approach for mapping seagrass cover from data sources commonly collected by natural resource management agencies responsible for coastal environments. The aim of the study was to develop an approach for mapping classes of seagrass cover from field and/or image data for an area with variable water clarity and depths. The study was carried out in Moreton Bay in eastern Australia. A Landsat 5 Thematic Mapper satellite image was acquired for the same area in August 2004. The image data were used to map seagrass cover in the exposed inter-tidal and clear shallow water areas to depths of 3 m. Field survey data were collected, in July – August 2004, to map deep (> 3 m) and turbid sub-tidal areas, using: real time video, snorkeller observations and transect surveys . The resulting maps were combined into a single layer of polygons, with the same seagrass cover classes used as existing mapping programs and with each polygon assigned to one of five cover classes (0 %, 1-25 %, 25-50 %, 50-75 %, 75-100 %). As independent field data were not available for accuracy assessment, a reliability assessment indicated that > 75 percent of the Bay was mapped with high categorical reliability. Most previously published seagrass mapping projects covered areas < 400 km2, were based on single data sets, and lacked assessment of accuracy or reliability. Our approach and methods address this gap and present guidelines for a generally applicable method to integrate image and field data sets over large areas (> 1000 km2) commonly used for monitoring and management..
Least Cost Path for Green Corridors Delineation in Metropoltan Margins: the Distance Weighting Effects
Y. Cohen Agricultural Engineering Institute ARO – the Volcani Center Bet Dagan 50250, Israel
I. Amit-Cohen Department of Geography Bar-Ilan University Ramat Gan, Israel
A. Cohen Agricultural Engineering Institute ARO – the Volcani Center Bet Dagan 50250 and Department of Transportation and Geoinformation Engineering Technion–Israel Institute of Technology Haifa, Israel
M. Shoshani Department of Transportation and Geoinformation Engineering Technion–Israel Institute of Technology Haifa, Israel
Abstract The optimum path found by the least-cost path (LCP) method is determined by the cost surface as well as the distance. In environmental applications it is not desirable that distance makes a significant impact. Instead, the decision maker seeks for the LCP that reflects the environmental cost surface. However, in most studies this impact is overlooked, and the resulting LCP does not provide this type of optimum path. In the present study the impact of the distance on the LCP is demonstrated by delineation of green corridors in the southern margins of the central metropolis of Israel. The research shows that a cost surface based on an inappropriate encoding type leads to a 'minimum-distance path' instead of an LCP that reflects the environmental cost surface. It is concluded that non-linear encoding types, with sizeable separations between environmental cost classes, provide a suitable balance between habitat suitability, minimum Euclidean distance, and degree of ‘connectivity’ between core areas.
Exploring the Spatio-temporal Dynamics of Fire Incidence and the Influence of Socio-economic Variables: A Case Study from South East Queensland, Australia
J. Corcoran Geography, Planning and Environmental Management University of Queensland St. Lucia, Brisbane Queensland, Australia
R. Stimson University of Queensland Social Research Centre (UQSRC) Institute of Social Science Research (ISSR) University of Queensland St. Lucia, Brisbane Queensland, Australia
P.Chhetri School of Management, College of Business RMIT University, Melbourne, Victoria, Australia
Abstract Using four types of fire incidence, namely calls for property, vehicle, secondary fires and malicious false alarms, this paper explores their spatio-temporal dynamics and the relationship to socio-economic status. Combining both spatial and temporal dimensions using a novel technique, called the ‘comap’, each incident type is visually explored, arguing that its application permits new insights into their dynamics and allows questions such as – for a particular type of fire incident - what are the salient spatio-temporal patterns and how do these vary for differing levels of disadvantage, to be answered for the first time.
One Strategy for Repositioning Spatial Sciences Education in Australia
R. Bennett C. Ogleby I. Bishop Department of Geomatics The University of Melbourne Victoria 3010, Australia
Abstract Australian spatial sciences education is facing a paradox: the demand for graduates is steadily increasing yet enrolments remain static. This paper examines a new strategy aimed at resolving the paradox. To this end, the University of Melbourne’s new degree structure and its impact on Geomatics are examined. The new model enables students to obtain a Geomatics Major within three years - as part of a Science or Environments degree - or a Masters in Engineering (Geomatics) within five years. Results from the first year of implementation suggest there have been increases in student quality, student engagement and the exposure of spatial sciences to undergraduates. Enrolments suggest Geomatics has halted the recent decline in numbers; however, it is too soon to determine what increases, if any, the Masters program might achieve. This paper suggests that the new model will produce both pure spatial science professionals and spatially skilled workers in other professions: both are required to combat existing skills shortages. The new model should be viewed within a larger set of industry-wide strategies to increase professional numbers.
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