Contours - 1 metre - Queensland - by area of interest

Delivery point: 275 George Street
City: Brisbane
State: Qld
Postcode: 4000
Country: Australia
Email: opendata@dnrme.qld.gov.au

The original source data was captured by project using Airborne Laser Scanning from a fixed wing aircraft with the acquisition over tidal areas being undertaken within +/- 2 hours of low tide. The capture of airborne LiDAR was supported by the establishment of GPS base stations with aerial control maintained via the LiDAR systems IMU and the GPS base stations.

Laser strikes have been classified into ground and non-ground based upon algorithms tailored for major terrain - vegetation combinations existing in the project area. The definition of the ground may be less accurate in isolated pockets of dense vegetation and certain types of vegetation such as sugar cane.

The ground filtered dataset is then visually checked by an operator, and incorrectly classified data is corrected or the ground filtering algorithm is adjusted and then visually checked. For the verification of the ground classifications, intensity imagery may be used as a backdrop image. Any LiDAR return, not classified as ground, but higher than ground, >30cm above ground, is classified as non-ground return.

From this ground dataset, contours with a 25 centimetre interval in height are generated. Data is stored in MGA coordinates in GDA94 in either 1 km or 2 km tiles depending on the project specifications with heights being recorded in AHD71. The tile number is either the coordinate of the North West or South West corner of the tile.

This dataset was compiled by extracting out the 1 metre contour from the exiting 25 centimetre contour datasets. As the original data is stored in either 1 km or 2 km tiles and in project areas, the data has been merged into continuous line strings within a project and location. The data is also converted to latitude and longitude in GDA94.

Feature Types:

BASIC CONTOUR - An imaginary line on the ground joining points of equal elevation at a regular spacing of 1 metre above the Australian Height Datum. Contours with an elevation evenly divisible by 5 are classified as major contours e.g. 5m, 10m 15m.
MAJOR CONTOUR - An imaginary line on the ground joining points of equal elevation at a regular spacing of 5 metres above the Australian Height Datum.

Attributes:

FEATURE - Unique feature type that identifies the topographic feature e.g. Major Contour.
TYPE - For use in ESRI Geodatabase only (display purposes)
ELEVATION - Elevation in metres in relation to the Australian Height Datum
FEATURERELIABILITY - Reliability date of the source information
FEATURESOURCE - The data that the spatial location of the feature was obtained from.
ATTRIBUTERELIABILITY - Reliability date of the data that the name of the feature was acquired from.
ATTRIBUTESOURCE - The data used for attributing (naming) of the feature e.g. Major Contour
PLANIMETRICACCURACY - The standard deviation of the horizontal positional accuracy.
ELEVATIONACCURACY - The vertical accuracy of the data to the nearest metre

Instructions: Open the Queensland Spatial Catalogue (QSpatial). Select the large SEARCH button and all available records are displayed. Select one of the four filter options provided and then the further options within the filter. The resultant search is then displayed. Select your record and complete the order.

Name/identifier: From the Queensland Spatial Catalogue available as ESRI Shape file SHP, MapInfo Tab file TAB, ESRI file geodatabase FGDB, Google file KMZ, and Geopackage version 1.0, 1.1, or 1.2 file GPKG

Website: Function: download