LIST Hydrographic Area depicts all waterbody and associated polygon features in the hydrographic theme including lakes, estuaries, dams, mudflats, swamps and coastal flats. It contains attributes that allow area features to be delivered in separate layers and with attributes. The data set is held as regions which allow area features to overlap.
WATER Hydrology ;
MARINE Coasts ;
WATER Lakes ;
WATER Rivers ;
Some data was captured directly from aerial photography by digital photogrammetric plotters using 3DD software with recorded X, Y, Z coordinates. This data was then converted to Microstation DGN format with the drainage, roads and limited cultural themes dropped to 2D.
For the majority of information, the data was captured from aerial photography by graphical photogrammetric plotters. For some majority of these areas, the components of the printed maps were then scanned, vectorised and georeferenced. For the remaining features, the photogrammetrical machine plots were scanned, georeferenced and on screen hand digitised.
The data was then taken into Arcinfo and attributed before being stored in the LIST Database.
Revision of data is in Microstation using a soft photogammetrical workstation capturing 3D data. The data has been dropped to 2D, converted to ArcInfo and attributed before being stored in the LIST Database.
LIST Hydrographic Area is a compilation of -
1:25 000 Digital Data - Photogrammetric has the following accuracy: - Horizontal: Not less than 90% of well defined detail is within 12.5 metres of true. 1:25 000 Digital Data - Scanned and on screen digitising has the following accuracy: - Horizontal: Not less than 90% of well defined data is within 17.5 metres of true position. 1:5 000 Digital Data - Photogrammetric data has the following accuracy: - Horizontal: Not less than 90% of well defined data is within 2.5 metres of true. 1:5 000 Digital Data - Scanned and on screen digitising, has the following accuracy: - Horizontal: Not less than 90% of well defined data is within 3.5 metres of true position. These accuracies may not be achieved in areas of dense vegetation.
For the majority of LIST Hydrographic Line features, primary positional accuracies can be obtained from the feature metadata information in the Hydrographic Line layer.
The attributes associated with LIST Hydrographic Area were primarily assigned from aerial photography, the photogrammetrical machine plots and the printed maps. The accuracy of the attribute information is estimated at 98%.
All lines and polygons are labeled with a Unique Feature Identifier (UFI). This UFI is linked to a Feature Metadata Pointer (FMP) which contains the aerial photography date, horizontal and vertical accuracy and the metadata directory number. All data has been checked both visually and by automated processes for undershoots, overshoots and correct data attribution.
The LIST Hydrographic Area is complete for all Tasmania excluding Macquarie island.