Abstract |
LIST Hydrographic Line depicts all line features in the hydrographic themes including rivers, coastline, shoreline of lakes. It contains attributes that allow lines to be delivered in separate layers and with attributes. Some lines, associated with Dam 2Ds, Rapid 2Ds, Submerged Trees, Submerged Reefs and Land, will not be replicated into separate data sets. |
Lineage Statement |
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 lines, 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. |
Lineage Description |
Position Accuracy:
LIST Hydrographic Line 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.
Some features, although mapped at a particular scale, are not well defined and have following accuracy :-Horizontal: Not less than 90% of data is within 30 to 100 metres of true position.
These accuracies may not be achieved in areas of dense vegetation.
Attribute Accuracy:
The attributes associated with LIST Hydrographic Line dataset were primarily assigned from aerial photography, the photogrammetrical machine plots and the printed maps. The accuracy of the attribute information is estimated at 98%.
Logical Consistency:
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.
Completeness:
The LIST Hydrographic Line dataset is complete for all Tasmania excluding Macquarie Island. |