This original datasets that this dataset has been compiled from were captured using photogrammetry. Data captured prior to the early 1990s was captured using an analytical method of photogrammetry. This means that contours were captured and transposed directly onto stable film (called repromats). This plotted line work was then used in the mapping process. To convert this line work to digital data, a project was undertaken in the 2000s to scan and digitise these repromats. Heights were recorded on the repromats which was transposed to the digital data as an elevation attribute. In the early 1990s, this analytical process was replaced by a digital method where the data was captured directly as 3D data in a digital format.
The original datasets were stored in department servers in 1:25000 map tiles in MGA94 (GDA94) and generally in 1:100000 blocks which had the same source information. These individual tiles have been merged based on the source information and elevation value into continuous line strings across 1:25000 map tile boundaries using ArcGIS in Latitude/Longitude (GDA94). The elevation value is stored within the data has an attribute.
Those early features that had an imperial contour interval had the elevation value converted to the nearest minute.
The Contours - 5 metre - Queensland dataset were all of the states 5 metre contours are stored is an ESRI Geodatabase that agrees with the Geoscience Australia Topographic Database Schema in Latitude/Longitude (GDA94). This downloadable dataset is a subset of the ESRI Geodatabase that has been converted to ESRI Shape format. Some columns names have been altered to allow for the shortened column name description in the shape format.
Imperial Contour - An imaginary line on the ground joining points of equal elevation at a regular spacing that is measured in feet above the Australian Height Datum. This feet measurement was converted to the nearest metre (in this dataset it generally varies between 7 or 8 metres)
Index Contour - An imaginary line representing every fifth intermediate contour (in this dataset at 25 metre intervals)
Intermediate Contour - An imaginary line on the ground joining points of equal elevation at a regular spacing above the Australian Height Datum (in this dataset at 5 metre intervals)
Feature - Unique feature type that identifies the topographic feature e.g. Index Contour
Name - The name of the feature (if available)
Elevation - The elevation of the feature above the Australian Height Datum
SourceDate - Reliability date of the source information
Source - The imagery, map or data that the spatial location of the feature was obtained from.
AttDate - Reliability date of the document or authority that the name of the feature was acquired from.
AttSource - The source (imagery, map or data) used for attributing (naming) of the feature. If no name is present then the attribute source will be the imagery, map or data used to define the feature type e.g. town water supply
PlanAccur - Planimetric Accuracy - The standard deviation of the horizontal positional accuracy.
ElevAccur - Elevation Accuracy - The accuracy of the vertical elevation of the data