Input Dataset

NSW Crossing Dataset

Theme 
Transport
Jurisdiction 
NSW
Custodian 
Spatial Services

Contours are virtual imaginary lines on the ground, joining points of an equal elevation in relation to the Australian Height Datum (AHD). It is a line feature class of the NSW Digital Topographic Database ( DTDB), within the Physiography theme. A contour can be a standard contour, depression contour or an ancillary contour. The Elevation attribute is defined as the distance along the vertical (direction of gravity) from the geoid (approximately mean sea level) to a point. The elevation range is -4 m to 2220 m.
There is no overall accuracy reported in the database, however accuracy of the individual feature instances of each feature class can be found in the database tables. The currency of the feature instances in this dataset can be found in “feature reliability date” or “attribute reliability date” attributes. All feature instances in this class are attributed with a planimetric accuracy value. It is expected that the 90% of well-defined points with the same planimetric accuracy are within 0.5mm of that map scale. Depending on the capture source, capture method, digital update and control point upgrade, every feature instance reported has a positional accuracy within the range of 1m - 100m. For detailed definitions on all feature classes and attributes, refer to the DTDB Data Dictionary.This dataset is available for download through the clip & Ship application in LPI’s Online Shop. The download link is provided in the distribution section of this metadata statement. Some of the production related attributes have been removed from this dataset so as to simplify the data schema and improve data delivery performance. Based on the area of interest this feature class may or may not be present.

Dataset Purpose

The DTDB is primarily used for planning, developmental activities, navigation and resource monitoring by emergency services, the Defence Forces, environmental resource managers and engineers. This information is also commonly used by bushwalkers, canoeists, anglers and fossickers to establish a detailed picture of the local environment.

Funding Support

Access Format

GeoDatabase(gdb), Shape(shp), ESRI SDE, Well Known Text(wkt), Data Exchange Format(dxf),Oracle(SDO), MapInfo(MID/MIF/TAB)

Dataset Lineage

The original mapping information that constitutes the DTDB was initially created from 1970 at 1:25 000, 1:50 000 and 1:100 000 scales from stereoscopic aerial photography supported by ground truth, field data capture and updating. These scales have an inherent accuracy as per the National Mapping Council of Australia, Standards of Map Accuracy (1975). Therefore, the position of the feature instance will be within 0.5mm at map scale for 90% of the well-defined points. That is, 1:25000 = 12.5 m, 1:50000 = 25 m and 1:100000 = 50 m. The original manuscripts were scanned and vectorised and translated to Genamap files. Beginning in 2004, the data was migrated to an ESRI geodatabase. Since then the database has been continuously updated and upgraded through a program of external data integration from custodial and other sources, data matching and data verification of other internal and external databases, field investigation and research, as well as through Land and Property Information (LPI)’s regular cycle of updating aerial imagery of 10 cm, 50 cm and 2.5 m GSD. The programs address the content correctness, currency and accuracy of different Feature Classes on a continuous or cyclical basis. The specific programs utilised for the maintenance of each feature are largely defined by the Capture Source Attribute attached to the feature. Data is updated via multiple source programs and captured using various methods; Registered Image Trace, Ortho Image Trace of 10 , 20 and 50 cm ground sample distance imagery from ADS and 2.5 m from SPOT 5 imagery , Table Digitisation , DCDB , Scan / Vectorise , Differential GPS , Non-corrected , Comparative estimate , Survey Controlled , Mobile GPS , Stereo Image Trace Aggregation or replication of existing line segments , Engineering Design File (CAD) Scanned Map Image Trace , Positioned within features cadastral or ortho image extent. Some capture methods are unknown which may occur where data was supplied by an external source where the data capture method is undefined. Depending on the capture source, capture method, digital update and control point upgrade, every feature instance reportedly has a positional accuracy within the range of 1 m-100 m. It is important to note that not all features may be captured within the database for each feature class, and may not be an accurate representation of the current state.

Access and Licensing

Creative Commons Attribution 3.0

Identified Mandate

Yes

Content Source

National datasets

National Crossings