3D model
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AAMHatch acquired Airborne Laser Scanning (ALS) data for the Sydney Metropolitan area between 11 June 2007 & 7 July 2007 and again in February to June 2008. The source data are available as mass points (ASCII XYZ, LAS) and Gridded 2m and 10m DEM tiles or 2m Mosaic. The vertical accuracy is 0.15m at 1 sigma in open clear ground as specified in the project scope. A hydrologically conditioned and drainage enforced 2m DEM or HDEM has also been developed by SKM in both MGA Zone 56 and in GCA GDA94 projection in ESRI GRID format. Hydrologic enforcement and conditioning has included the testing of data for sinks, the referencing of transport and hydrology vector layers for intersections and flow, and the use of high-resolution imagery for visual validation. The methodology for hydrologic enforcement has required deriving a stream network based on flow direction and accumulation, using TIN and ANUDEM processes to analyse sinks and artificial damming affects caused by objects such as roads, bridges and trees which have not been previously filtered. Break lines have been included via the insertion of culvert/drainage channels, which has been used to interpolate these features into the main DEM as descending grid values. All data are referenced to GDA94/MGA Zone 56 and AHD using independent survey control which means the project area is not seamless and height difference between the 2007 and
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Geoscience Australia (GA) has developed an interactive 3D virtual globe viewer to facilitate effective communication of geoscience data and scientific findings to a wide range of stakeholders. The interactive virtual globe is built on NASA's open source World Wind Java Software Development Kit (SDK) and provides users with easy and rich access to geoscientific data. The tool has been used to launch a number of national and regional datasets, including sub-surface seismic and airborne electromagnetic data (AEM) in conjunction with other relevant geoscience data. For the Broken Hill Managed Aquifer (BHMAR Project, there was a requirement to further develop the existing viewer platform in order to display complex 3D hydrogeological, hydrogeophysical and hydrogeochemical data (points, lines, 2D surface and 3D shapes). The final product includes support for a variety of geo-referenced raster data formats, as well as vector data such as ESRI shapefiles; native support for a variety of GOCAD data types including TSurf, SGrid, Voxet and PLine. It also supports well and borehole data including attribute-based styling of log features and the ability to include legends and descriptions of data within the user interface. An easy-to-use interface has been customised for navigation of data in 3D space using a virtual globe model, with powerful keyframe based animation tools used to generate flythrough animations for use in knowledge communication workshops. The products will be distributed as data layers via the internet and as a stand alone DVD package.
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Geoscience Australia has developed an interactive 3D viewer for three national datasets; the new Radiometric Map of Australia, the Magnetic Anomaly Map of Australia, and the Gravity Anomaly Map of the Australian Region. The interactive virtual globe is based on NASA's open source World Wind Java Software Development Kit (SDK) and provides users with easy and rich access to these three national datasets. Users can view eight different representations of the radiometric map and compare these with the magnetic and gravity anomaly maps and satellite imagery; all draped over a digital elevation model. The full dataset for the three map sets is approximately 55GB (in ER Mapper format), while the compressed full resolution images used in the virtual globe total only 1.6GB and only the data for the geographic region being viewed is downloaded to users computers. This paper addresses the processes for selecting the World Wind application over other solutions, how the data was prepared for online delivery, the development of the 3D Viewer using the Java SDK, issues involving connecting to online data sources, and discusses further development being undertaken by Geoscience Australia.
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The Capel and Faust Basins in Australia's remote eastern offshore frontier, 800 km east of Brisbane in 1000-3000 m of water, are being studied as part of the Australian Government's Energy Security Initiative. A variety of geophysical data has been obtained and efforts are currently focussed on integrated interpretation of 2D seismic reflection data, sonobuoy refraction data and marine potential-field data. Negative residual gravity anomalies generally correlate with basins evident in the seismic reflection data. The anomalies highlight elongate, roughly N-S-trending or arcuate depocentres, with limited strike extent, that are best developed in the north and northwest of the survey area where increased crustal extension appears to have occurred. The 20-50 km separation between 2D seismic lines and the isolated nature of the basin depocentres complicates the process of linking structures between lines, but 3D mapping of faults and horizons is facilitated by the potential-field data. Instead of correlating with depocentres and basement highs, reduced-to-pole positive magnetic anomalies may reflect the distribution of volcanics and intrusives, variably evident as high-amplitude or low-frequency reflectors, and volcanic features at or near the seafloor. Interpretation of the seismic reflection data suggests the presence of four main syn-rift megasequence packages (?Early Cretaceous-?Santonian) and several post-rift sag packages (?Early Campanian-Recent). Maximum unequivocal depocentre thickness is ~4s TWT. Forward and inverse modelling of the gravity and magnetic data in 3D is providing a means to characterise different basement terranes and to construct surfaces that represent the sequence boundaries within the depocentres.
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The Capel and Faust basins are located on the northern Lord Howe Rise in water depths of 1300-2500 m. Geoscience Australia recently completed a geological and petroleum prospectivity assessment of the area based on new seismic, potential field, multibeam bathymetry and rock sample data. The data sets were acquired under Australian Geovernment initiatives aimed at providing pre-competitive information to industry.
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Australia's marine jurisdiction is one of the largest and most diverse in the world and surprisingly our knowledge of the biological diversity, marine ecosystems and the physical environment is limited. Acquiring and assembling high resolution seabed bathymetric data is a mandatory step in achieving the goal of increasing our knowledge of the marine environment because models of seabed morphology derived from these data provide useful insights into the physical processes acting on the seabed and the location of different types of habitats. Another important application of detailed bathymetric data is the modelling of hazards such tsunami and storms as they interact with the shelf and coast. Hydrodynamic equations used in tsunami modelling are insensitive to small changes in the earthquake source model, however, small changes in the bathymetry of the shelf and nearshore can have a dramatic effect on model outputs. Therefore, accurate detailed bathymetry data are essential. Geoscience Australia has created high resolution bathymetry grids (at 250, 100, 50 and 10 metres) for Christmas, Cocos (Keeling), Lord Howe and Norfolk Islands. An exhaustive search was conducted finding all available bathymetry such as multibeam swath, laser airborne depth sounder, conventional echo sounder, satellite derived bathymetry and naval charts. Much of this data has been sourced from Geoscience Australia's holdings as well as the CSIRO, the Australian Hydrographic Service and foreign institutions. Onshore data was sourced from Geoscience Australia and other Commonwealth institutions. The final product is a seamless combined Digital Bathymetric Model (DBM) and Digital Elevation Model (DEM). The new Geoscience Australia grids are a vast improvement on the existing publicly available grids. These grids are suitable for: tsunami modelling, storm surge modelling, ocean dynamics, environmental impact studies, marine conservation and fisheries management.
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Deep-water Otway and Sorell basins developed during Gondwana break-up when Australia rifted away from Antarctica. The 2D and 3D gravity modelling in conjunction with seismic and geological interpretation has led us to an improved understanding of basement architecture of the study area. 2D gravity modelling particularly along selected seismic lines reveals a N-S crustal-scale lineament extending down to the Moho. A distinct density contrast of 0.16 t/m3 (3.05 t/m3 and 2.89 t/m3) across the structure points to a significant lithological difference at middle to lower crustal depths, interpreted here to reflect a change from dominantly basaltic to felsic lower crust. This structure is assumed to be inherited from a pre-existing basement structure and supports the hypothesis that the evolution of the Sorell Basin was probably basement controlled. The 2D models also help us to conclude the basaltic underplating in the lower-crustal region resulting from the breakup history, all long the margin. The computed 3D gravitational response of the basin-wide seismic interpretation correlates moderately well to the observed gravity trend, which implies (a) consistency between the seismic and gravity data of the inferred model. (b) Throws some light on basement topography, hence gives an idea of possible depo-centres. The depth to magnetic basement map derived independently from magnetic data has given a close proximity with that obtained from the 3D forward modelling, which essentially enhance reliability on the derived model to a good extent.
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The subsurface of the Earth is a complex system, one that we are yet to fully understand and model. It is hence impossible to automate the process of mapping and modelling, and the input of user experience and knowledge ('prior knowledge') is required to produce meaningful and useful outputs. This form of solution does not lend itself to a simple programmatic approach. However, by taking advantage of advances in computer technology and the application of numerical methods for modeling complex environments, we can do much to improve upon past results. Introduction As Australia's national geoscience organisation, Geoscience Australia (GA) plays an important role in the creation and delivery of fundamental geoscientific information. Studies are carried out at a wide range of scales, from a continental perspective to highly detailed local site investigations. In most situations, direct geological observations are supplemented by the inferences that can be made from geophysical measurements. Observations of the Earth's gravity and magnetic fields contain signals from subsurface materials, and extensive holdings of these measurements are commonly used to help create 3D subsurface models. With sparse hard constraints and incomplete, insufficient, noisy observations, knowledge workers or experts continue to play an important role in providing implicit prior constraints on any system to model this volume. The interface to these people becomes an important part of any set of tools for performing geological modeling of gravity and magnetic data. Users constantly demand a better experience and better outcomes when modeling the subsurface. Some of their recurring requests are for: * A simpler, more intuitive user-experience * Higher resolution * Models with larger extents * Faster processing * Inclusion of a greater number of geological and rock property constraints * Estimates of the uncertainty in the outcomes * Improved 3D visualisation * Tracking of input provenance and subsequent processing that is carried out * Organised management of 3D models Integration of the elements is a key consideration when developing solutions, as users are loathe to adopt procedures that become more involved and more difficult to understand and to piece together. Today, developments to produce world-class solutions typically take place across multiple agencies, involving many people, and at locations spread around the globe. This in itself is a challenge! We have focused our efforts on the following: * The management and delivery of rock properties * Spherical and Cartesian coordinate gravity and magnetic modelling software * Use of High Performance Computing (HPC) facilities * Use of a virtual globe application for 3D visualisation
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Geoscience Australia has developed an interactive 3D viewer for three national datasets; the new Radiometric Map of Australia (Geoscience Australia 2009b), the Magnetic Anomaly Map of Australia (Geoscience Australia 2004), and the Gravity Anomaly Map of the Australian Region (Geoscience Australia 2008). The interactive virtual globe is based on NASA's open source World Wind Java Software Development Kit (SDK) and provides users with easy and rich access to these three national datasets. Users can view eight different representations of the radiometric map and compare these with the magnetic and gravity anomaly maps and satellite imagery; all draped over a digital elevation model. The full dataset for the three map sets is approximately 55GB (in ER Mapper format), while the compressed full resolution images used in the virtual globe total only 1.6GB and only the data for the geographic region being viewed is downloaded to users computers. This paper addresses the processes for selecting the World Wind application over other solutions, how the data was prepared for online delivery, the development of the 3D Viewer using the Java SDK, issues involving connecting to.
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The Capel and Faust basins are located over the northern part of the Lord Howe Rise, a large offshore frontier region containing a number of basins with untested petroleum prospectivity. Recent data acquisition by Geoscience Australia has significantly improved geological knowledge of these basins. Given the diversity of acquired data, comparative sparseness of data coverage, lack of deep drilling control, and complexity of geological structure, effective data integration and analysis methods were essential for a meaningful geological interpretation of the Capel and Faust basins. By using the 3D visualisation and modelling environment provided by GOCAD, the datasets were captured, processed and interpreted to create an integrated 3D model that enabled key geological and prospectivity questions to be answered. This presentation summarises the construction methodology and the resulting geological and prospectivity implications of the Capel-Faust 3D geological model.