This service represents a combination of two data products, the DEM_SRTM_1Second dataset and the Australian_Bathymetry_Topography dataset. This service was created to support the CO2SAP (Co2 Storage application) Project to create a transect elevation graph within the application. This data is not available as a dataset for download as a Geoscience Australia product.
The DEM_SRTM_1Second service represents the National Digital Elevation Model (DEM) 1 Second product derived from the National DEM SRTM 1 Second. The DEM represents ground surface topography, with vegetation features removed using an automatic process supported by several vegetation maps. eCat record 72759.
The Australian_Bathymetry_Topography service describes the bathymetry dataset of the Australian Exclusive Economic Zone and beyond. Bathymetry data was compiled by Geoscience Australia from multibeam and single beam data (derived from multiple sources), Australian Hydrographic Service (AHS) Laser Airborne Depth Sounding (LADS) data, Royal Australian Navy (RAN) fairsheets, the General Bathymetric Chart of the Oceans (GEBCO) bathymetric model, the 2 arc minute ETOPO (Smith and Sandwell, 1997) and 1 arc minute ETOPO satellite derived bathymetry (Amante and Eakins, 2008). Topographic data (onshore data) is based on the revised Australian 0.0025dd topography grid (Geoscience Australia, 2008), the 0.0025dd New Zealand topography grid (Geographx, 2008) and the 90m SRTM DEM (Jarvis et al, 2008). eCat record 67703.
IMPORTANT INFORMATION For data within this service that lays out of the Australian boundary the following needs to be considered.
This grid is not suitable for use as an aid to navigation, or to replace any products produced by the Australian Hydrographic Service. Geoscience Australia produces the 0.0025dd bathymetric grid of Australia specifically to provide regional and local broad scale context for scientific and industry projects, and public education. The 0.0025dd grid size is, in many regions of this grid, far in excess of the optimal grid size for some of the input data used. On parts of the continental shelf it may be possible to produce grids at higher resolution, especially where LADS or multibeam surveys exist. However these surveys typically only cover small areas and hence do not warrant the production of a regional scale grid at less than 0.0025dd. There are a number of bathymetric datasets that have not been included in this grid for various reasons.
Statement: Lineage: For lineage descriptions for input dataset please see the individual metadata records. The Australian_Bathymetry_Topography service eCat record 67703. The DEM_SRTM_1Second service eCat record 72759.
Service creation lineage: This service is in the Geographic Coordinate System GCS_WGS_1984, WKID: 4326, Authority: EPSG, Datum: D_WGS_1984, Spheroid: WGS_1984. All datasets that differed from this were reprojected into this coordinate system prior to data manipulation.
This service was created by converting the individual DEM_SRTM_1Second raster tiles from GRID format to TIFF using Conversions (Raster To Other Format) tool. A Clipping layer was then created by using Political_Boundary_Area layer from within the Global Map service (eCat 83575). The polygons within this layer were merged into a single polygon. Each of the coastal DEM_SRTM_1Second raster tiles were then clipped using the FME clipper transformer using this layer. These clipped tiles were then merged with the rest of the individual DEM_SRTM_1Second raster tiles using the Data_Management (Mosaic To New Raster) tool within ArcGIS into a single raster. The Australian_Bathymetry_Topography was then resampled using the Data_Management (Resample) tool within ArcGIS to resample to the DEM_SRTM_1Second cell size, 32 bit float and snap to this layer. The resampling technique used is nearest neighbour assignment. A fishnet was then created using the Australian_Bathymetry_Topography as the extent to create and 18 cell (6 x 3) grid. This Fishnet cells were then used as a mask to extract even clips of both the Australian_Bathymetry_Topography and the DEM_SRTM_1Second rasters in individual tiles using the Spatial_Analyst (Extract by Mask) tool within ArcGIS. Tiles were overlaps of these two raster datasets occurred were then merged together using Data_Management (Mosaic To New Raster) using the DEM_SRTM_1Second raster as the priority. The Data_Management (Mosaic To New Raster) tool was then used to merge all final rasters together into the Final complete dataset.