Abstract |
LIST contours consist of linear features which depict an imaginary line representing a constant elevation on the Earth's surface. There are two datasets available - Contours 10m and Contours 5m.
Contours 10m depicts contour lines at 10 metre intervals which were created for the 1:25,000 map series and coverage includes all Tasmania and offshore islands excluding Macquarie Island. This is a seamless coverage and attributes are complete.
Contours 5m depicts contour lines at 5 metre intervals which were created for the former 1:5,000 Orthophoto/Cadastral map series and coverage generally only extends to urban areas and towns. This data is not seamless and edge matching has not been completed for all the map sheet tiles in this coverage. There may be incomplete data in some areas where dense vegetation is present. This dataset is not being revised. |
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. For the majority of information, the data was captured from aerial photography by graphical photogrammetric plotters. For the majority of lines, the components of the printed maps were then scanned, vectorised and georeferenced. The data was then taken into Arcinfo and attributed before being stored in the LIST Database. Revisions of data were acquired in Microstation DGN format using a softcopy photogammetrical workstation capturing 3D data. The data was converted to ArcInfo and attributed before being stored in the LIST Database. |
Lineage Description |
Position Accuracy:
LIST Contours 10 have a vertical accuracy such that not less than 90% of the contours are within 5 metres of true height.
LIST Contours 5 have a vertical accuracy such that not less than 90% of the contours are within 2.5 metres of true height.
These accuracies may not be achieved in areas of dense vegetation or where the ground surface is obscured for other reasons.
Attribute Accuracy:
The attributes associated with LIST Contour Data 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 10 metre contour data has been checked both visually and by automated processes for undershoots, overshoots and correct data attribution. Contours 5 have not been edge matched and may have some topological inconsistencies. The 5m contours and 10m contours were developed independently and will not match.
Attributes include the type of contour whether Intermediate, Index, Depression, etc (CONTOUR_TY) and the Elevation of the contour line in metres above Australian Height Datum (ELEVATION).
Completeness:
10m contours is complete and includes all Tasmania and offshore islands excluding Macquarie Island.
5m contours generally only covers urban areas and towns and are incomplete in areas of dense vegetation. |