The 3 second (~90m) Shuttle Radar Topographic Mission (SRTM) derived Digital Surface Model (DSM) Version 1.0 was derived from resampling the 1 arc second (~30m) gridded DSM (ANZCW0703013336) that represents ground surface topography as well as features above the ground such as vegetation and man-made structures. The 1 second DSM was derived from the SRTM data acquired in February 2000, supported by the GEODATA 9 second DEM in void areas and the SRTM Water Body Data. Stripes and voids have been removed from the 1 second SRTM data to provide an enhanced and complete DSM for Australia and near-shore islands. A full description of the methods is in progress (Read et al., in prep). The 3 second DEM was produced for use by government and the public under Creative Commons attribution. Further information can be found in the User Guide. The 1 second DSM forms the source for the 1 second DEM with vegetation offsets removed (ANZCW0703013355) and the smoothed version (ANZCW0703014016). All 1 second products resampled to 3 seconds are available (DSM; ANZCW0703014216, DEM; ANZCW0703014182, DEM-S; ANZCW0703014217). <strong>Please note that all 1 second products are available for GOVERNMENT USERS ONLY.</strong>

The Perth 2008 LiDAR data was captured over the Perth region during February, 2008. The data was acquired by AAMHatch (now AAMGroup) and Fugro Spatial Solutions through a number of separate missions as part of the larger Swan Coast LiDAR Survey that covers the regions of Perth, Peel, Harvey, Bunbury and Busselton. The project was funded by Department of Water, WA for the purposes of coastal inundation modelling and a range of local and regional planning. The data are made available under licence for use by Commonwealth, State and Local Government. The data was captured with point density of 1 point per square metre and overall vertical accuracy has been confirmed at <15cm (68% confidence). The data are available as a number of products including mass point files (ASCII, LAS) and ESRI GRID files with 1m grid spacing. A 2m posting hydrologically enforced digital elevation model (HDEM) and inundation contours has also been derived for low lying coastal areas.

The Busselton 2008 LiDAR data was captured over the Busselton region during February, 2008. The data was acquired by AAMHatch (now AAMGroup) and Fugro Spatial Solutions through a number of separate missions as part of the larger Swan Coast LiDAR Survey that covers the regions of Perth, Peel, Harvey, Bunbury and Busselton. The project was funded by Department of Water, WA for the purposes of coastal inundation modelling and a range of local and regional planning. The data are made available under licence for use by Commonwealth, State and Local Government. The data was captured with point density of 1 point per square metre and overall vertical accuracy has been confirmed at <15cm (68% confidence). The data are available as a number of products including mass point files (ASCII, LAS) and ESRI GRID files with 1m grid spacing. A 2m posting hydrologically enforced digital elevation model (HDEM) and inundation contours has also been derived for low lying coastal areas.

Elevation data and products such as Digital Elevation Models derived from these data comprise an essential layer within the National Spatial Data Infrastructure. Historically the creation of these datasets has been the domain of National and State mapping agencies. However, in recent years the rapid development of survey technologies and industry capability, the need for high resolution elevation data to meet a range of purposes, and the nature of government funding arrangements has resulted in significant project-based investment.

An audit of high resolution elevation data capture in relation to densely populated areas was completed to: provide an overview of the status of high resolution elevation data acquisition around the coastal zone; and highlight areas for potential acquisition or further processing based on priorities identified through consultation with Commonwealth and State jurisdictions.

Data was collected by selecting the highest point(s) in each geographical area of 30 minutes of latitude by 30 minutes of longitude. Elevations are recorded in feet and metres (always rounded up). Information is derived from 1:1 Million scale World Aeronautical Charts. Note: This is not regularly gridded data.

The 2009 National Elevation Audit is a series of maps illustrating the areas where elevation data has been captured or will be completed until the end of 2009 and their relative vertical accuracy.

The Swan Coast hydrologically enforced digital elevation model (HDEM) was produced in 2010 as part of the Urban DEM project managed by the CRC for Spatial Information and Geoscience Australia. The HDEM was created from a combination of the following surveys; Perth, Peel, Harvey, Bunbury and Busselton LiDAR The Swan Coast 2008 LiDAR data was captured over the Swan Coast region during February, 2008. The data was acquired by AAMHatch (now AAMGroup) and Fugro Spatial Solutions through a number of separate missions as part of the larger Swan Coast LiDAR Survey that covers the regions of Perth, Peel, Harvey, Bunbury and Busselton. The project was funded by Department of Water, WA for the purposes of coastal inundation modelling and a range of local and regional planning. The data are made available under licence for use by Commonwealth, State and Local Government. The HDEM was produced by SKM using the ANUDEM program. The HDEM ensures that primary stream/channel flow, and water flow across the land surface are accurately represented. The hydrologically enforced HDEM depicts water bodies as being flat, and water courses depict consistent downward flow of water unimpeded by vegetation or man-made structures such as bridges and major culverts. Drainage enforcement was limited to watercourse lines depicted on 1:25,000 topographic mapping and to the intersection of the water course layer and transport layer. For the purposes of inundation modelling, inundation contours have been developed using the HDEM. The inundation extents were extracted at 0.2m intervals below 2m AHD and 1m intervals up to 10m. The inundation contours are available as polylines. The inundation contours have also been flagged as to whether the area connects directly to the sea. he data was captured with point density of 1 point per square metre and overall vertical accuracy has been confirmed at <15cm (68% confidence). The data are available as a number of products including mass point files (ASCII, LAS) and ESRI GRID files with 1m grid spacing.

Removing the topographic effect from satellite images is a very important step in order to obtain comparable surface reflectance in mountainous areas and to use the images for different purposes on the same spectral base. The most common method of normalising for the topographic effect is by using a Digital Surface Model (DSM) and / or a Digital Elevation Model (DEM). However, the accuracy of the correction depends on the accuracy, scale and spatial resolution of DSM data as well as the co-registration between the DSM and satellite images. A physics based BRDF and atmospheric correction model in conjunction with a 1-second SRTM (Shuttle Radar Topographic Mission) derived DSM product released by Geoscience Australia in 2010 were used to conduct the analysis reported in this paper. The results show that artefacts in the DSM data can cause significant local errors in the correction. For some areas, false shadow and over corrected surface reflectance factors have been observed. In other areas, the algorithm is unable to detect shadow or retrieve an accurate surface reflectance factor in the slopes away from the sun. The accuracy of co-registration between satellite images and DSM data is crucial for effective topographic correction. A mis-registration error of one or two pixels can lead to large error of retrieved surface reflectance factors in the gully and ridge areas (retrieved reflectance factors can change from 0.3 to 0.5 or more). Therefore, accurate registrations for both satellite images and DSM data are necessary to ensure the accuracy of the correction. Using low resolution DSM data in conjunction with high resolution satellite images can fail to correct some significant terrain effects. A DSM resolution appropriate to the scale of the resolution of satellite image is needed for the best results.

The 1 second SRTM derived DEM-H Version 1.0 is a 1 arc second (~30 m) gridded digital elevation model (DEM) that has been hydrologically conditioned and drainage enforced. The DEM-H captures flow paths based on SRTM elevations and mapped stream lines, and supports delineation of catchments and related hydrological attributes. The dataset was derived from the 1 second smoothed Digital Elevation Model (DEM-S; ANZCW0703014016) by enforcing hydrological connectivity with the ANUDEM software, using selected AusHydro V1.6 (February 2010) 1:250,000 scale watercourse lines (ANZCW0503900101) and lines derived from DEM-S to define the watercourses. The drainage enforcement has produced a consistent representation of hydrological connectivity with some elevation artefacts resulting from the drainage enforcement. A full description of the methods is in preparation (Dowling et al., in prep). This product is the last of the Version 1.0 series derived from the 1 second SRTM (DSM, DEM, DEM-S and DEM-H) and provides a DEM suitable for use in hydrological analysis such as catchment definition and flow routing.