image processing
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Hyperspectral images from the Eastern Fold Belt of the Mount Isa Inlier, released by the collaborative Queensland NGMM project between GSQ and CSIRO, were validated as new tool for the detection of IOCG related alteration. High resolution of mineral maps derived from hyperspectral imaging (4.5m/pixel) enables the recognition of various types of hydrothermal alteration patterns and the localisation of fluid pathways. Groundtruthing of a suite of mineral maps was conducted in 2007. Though sample analyses in the lab is still in process, but some preliminary results already show some promising features. In summary hyperspectral images provide a powerful tool for the recognition of various hydrothermal alteration patterns and could be used in combination with other geophysical remote sensing data, such as radiometrics and magnetics. Limitations of this technique are defined by unsatisfactory coverage of mineral maps, man made features, river systems and distribution and composition of debris. A good knowledge of the local geology is necessary to extract the full information provided by the mineral maps. Calibration of ASTER data with the hyperspectral data can hopefully extend interpretation made from the HyMap data into adjacent areas, which are only covered by ASTER. 60pp final report and databases.
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Soil mapping at the local- (paddock), to continental-scale, may be improved through remote hyperspectral imaging of surface mineralogy. This opportunity is demonstrated for the semiarid Tick Hill test site (20 km2) near Mount Isa in western Queensland. The study of this test site is part of a larger Queensland government initiative involving the public delivery of 25,000 km2 of processed airborne hyperspectral mineral maps at 4.5 m pixel resolution to the mineral exploration industry. Some of the mineral maps derived from hyperspectral imagery for the Tick Hill area include the abundances and/or physicochemistries (chemical composition and crystal disorder) of dioctahedral clays (kaolin, illite-muscovite and Al smectite, both montmorillonite and beidellite), ferric/ferrous minerals (hematite/goethite, Fe2+-bearing silicates/carbonates) and hydrated silica (opal) as well as soil water (bound and unbound) and green and dry (cellulose/lignin) vegetation. Validation of these hyperspectral mineral products is based on field soil sampling and laboratory analyses (spectral reflectance, X-ray diffraction, scanning electron microscope and electron backscatter). The mineral maps show more detailed information regarding the surface composition compared with the published soil and geology (1:100,000 scale) maps and airborne radiometric imagery (collected at 200 m line spacing). This mineral information can be used to improve the published soil mapping but also has the potential to provide quantitative information suitable for soil and water catchment modeling and monitoring.
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New ASTER GIS products in the Gawler-Curnamona Geoscience Australia, in collaboration with CSIRO and PIRSA are releasing a suite of 14 new ASTER mosaiced products for a significant part of the Gawler-Curnamona region. About 110 ASTER scenes have been mosaiced and processed into geoscience products that can be quickly and easily integrated with other datasets in a GIS. The products have been pre-processed and calibrated with available HyMap data and provide basic mineral group information such as Ferric Oxide abundance, AlOH group distribution as well as mosaiced and levelled false colour and regolith ratio images. These images, along with accompany notes are available for free ftp download online at: ftp://ftp.arrc.csiro.au/NGMM/Gawler-Curnamona ASTER Project/
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Legacy product - no abstract available
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If colour TMI map is purchased with greyscale TMI map the price is $269.80 (inc GST) for both
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Londonderry - Drysdale Potassium (red), Thorium (green), Uranium (blue) colour composite
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Legacy product - no abstract available
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Londonderry - Drysdale TMI (rtp) with northeast illumination
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The developed method of long-strip adjustment for orientation and georeferencing of PRISM imagery is based on the merging of successive images within a single satellite pass into what amounts to a single image covering the entire orbit segment. Metadata for each separate scene is merged to produce a single, continuous set of orbit and attitude parameters, such that the entire strip of tens of images can be treated as a single image, even though the separate scenes are not actually merged. Within the strip adjustment, the orbit parameters are refined based on the provision of GCPs at each end of the strip. A minimum of four GCPs is required to achieve 1-pixel georeferencing accuracy, even for strip lengths of 1000 km or more. The merging of orbit data results in a very considerable reduction in both the number of unknown orientation parameters and the number of required GCPs in the sensor orientation adjustment. Indeed the number of required GCPs can drop from well over 100 to only 4-6 for a 50-image orbit segment. Moreover, unlike in traditional photogrammetric strip adjustment, there is no need for tie-point measurements between images. Once the adjusted orbit parameters are obtained, the georeferencing and orthorectification process can revert to a fully automatic image-by-image computation. Following orthorectification, a final mosaicking is undertaken to produce the reference image, namely the AGRI. AGRI was needed because imagery from emerging new satellites can be automatically registered to it, consistently and accurately. AGRI was made possible by the developed long-strip adjustment approach to satellite image georeferencing. This technique, implemented in Barista, rendered the project feasible in time, logistics and cost. It reduced the image registration problem from correction of almost 10,000 scenes to correction of just 105 orbit segments. Moreover, the number of required GCPs was reduced from more than 30,000 to less than 1000.
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Identifying and mapping regolith materials at the regional and continental-scale can be facilitated via a new generation of remote sensing methods and standardised geoscience products. The multispectral Advanced Spaceborne Thermal Emission and Reflectance Radiometer (ASTER) is the first Earth observation (EO) system to acquire complete coverage of the Australian continent. The Japanese ASTER instrument is housed onboard the USA's Terra satellite, and has 14 spectral bands spanning the visible and near-infrared (VNIR - 500-1,000 nm - 3 bands @ 15 m pixel resolution); shortwave-infrared (SWIR - 1,000-2,500 nm range - 6 bands @ 30 m pixel resolution); and thermal infrared (TIR 8,000-12,000 nm - 90 m pixel resolution) with a 60 km swath. Although ASTER spectral bands do not have sufficient spectral resolution to accurately map the often small diagnostic absorption features of specific mineral species, which can be measured using more expensive 'hyperspectral' systems, current coverage of hyperspectral data is very restricted. The extensive coverage and 30m pixel size of ASTER make it well suited to national scale work. The spectral resolution of ASTER make it best suited to mapping broader 'mineral groups', such as the di-octahedral 'Al-OH' group comprising the mineral sub-groups (and their minerals species) like kaolins (e.g. kaolinite, dickite, halloysite), white micas (e.g. illite, muscovite, paragonite) and smectites (e.g. montmorillonite and beidellite). Extracting mineral group information using ASTER, using specially targeted band combinations, can find previously unmapped outcrop of bedrocks, weathering products, help define soil type and chemistry, and delineate and characterise regolith and landform boundaries over large and remote areas.