The Tasmania 25 metre Digital Elevation Model (DEM) is a regular grid of ground level elevation values spaced at 25 metre intervals across the extent of the land area of Tasmania and most of the associated islands, but excluding Macquarie Island.
This data is available only as an ASCII encoded text file (.asc)
GEOSCIENCES Geology ;
LAND Geodesy ;
The original source data for this DEM was derived from 1:25,000 Map Series data and consists primarily of 10m contours, spot heights over some areas, some waterbody polygons, and mean high water mark. Those areas where spot height data was available cover King Island, the Furneaux Group, Maria Island, and a number of 1:25,000 map sheets on mainland Tasmania.
Using Intergraph Terrain Analyst software the DEM was produced by creating a triangulated surface from the 10 metre contours, existing digital spot heights, water bodies where there was a known full supply level elevation attribute, and mean high water mark with an elevation attribute of 1 metre.
Users should be aware that drainage strings were not used in the generation of this DEM, therefore, it is not suitable for use in hydrological analysis.
The accuracy of the DEM is similar to the 1:25,000 Map Series data used as input; i.e. 90% of elevations are within 5m of true elevation. This accuracy may not be maintained in obscured areas effected by vegetation, or other obstructions, and in steep areas.
The elevation values are consistent in relation to the source data from which the DEM was derived.
The Tasmania 25 metre Digital Elevation Model exists for all of mainland Tasmania and most associated islands; with the most notable exclusion being Macquarie Island.
This latest 3rd Edition was produced in July 2007 which has corrected some errors identified in the previous edition. There are no plans to revise this data set.