LIST Hydrographic Points depicts all point features in the hydrographic themes including Offshore Rock, Tank, Water Tower, Waterfall, Spring, Wreck and Rapid.
WATER Hydrology ;
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 Rocks, Rapid 0Ds, Dam 0Ds and Springs the photogrammetrical machine plot was 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 Point 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.
These accuracies may not be achieved in areas of dense vegetation.
The attributes associated with LIST Hydrographic Point 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 Point is complete for Tasmania excluding Macquarie Island.