Input Dataset

Contours - 10 metre interval - by area of interest

Jurisdiction 
QLD

This dataset consists of 10 metre contours over the State of Queensland which has been compiled from numerous source datasets and generalized to an overall 1:50000 mapping accuracy to produce state wide 10m contour coverage.

Dataset Purpose

To provide digital elevation data for use in Land Administration, Emergency Management, Monitoring of Climate Change, Hydrological Modelling, and Topographic Mapping and in the production of Navigational and Web Based Mapping applications.

Funding Support

Access Format

SHP, TAB, GDB or KMZ

Dataset Lineage

In broad terms, the production process involved generating/deriving 10m contours for each of the source datasets and merging them together into a seamless dataset. Each type of source dataset required different types of processing to generate contours. Common to all sources was a process of generalisation to thin vertices, smooth and remove spikes and achieve a consistency in detail or resolution of the contour lines. Finally, contours from the different sources were merged ensuring matching off edges. SRTM derived Contours: a) A single mosaic was generated from the DSM_H (V1.0) ESRI grid files using ArcMap. b) The Mosaic was re-tiled into overlapping tiles with a 500m overlap using ArcMap. c) A value of 1.287 was subtracted from the height values of the DEM tiles (to adjust to AHD. (Value obtained from SRTM metadata statement). d) 10m contours were generated for each of the overlapping tiles using ArcMap (3D extension). e) The contour tiles were clipped back to the original tiles to remove overlap using ArcMap. f) Contours were smoothed using ArcMap (PAEK Algorithm).g) Contours were generalised using SAFE FME. Photogrammetrically derived contours: 10 metre contours derived from 1:50000 photogrammetry for the western portion of Cape York and the Southern gulf were complete and required no further processing. Contours derived from 1:50000 photogrammetry for the eastern portion of Cape York and North QLD originally had 20m (or greater) intervals. Similarly, portions of the 5 metre contours derived from 1:25000 photogrammetry had 20m (or greater) intervals, or irregular intervals, e.g. 15m, 25m, etc... In both cases, regular 10m contours were regenerated by: a) Generating a DEM from the existing contours (using pixel size 0.0002 degrees). b) Re-generate contours using same steps described the SRTM contours. LiDAR Contours: a) 10 metre LiDAR contours were extracted from existing 0.25m contours by script. b) Contours were smoothed, then generalised. Edge matching: Matching contours from different data sources was undertaken by using ArcMap to generate surface models over the overlap areas. This in effect blended the two sources together. Contours were regenerated for the overlap area and a cookie-cut replacement made into the base contours. Note that in some areas, contours of different sources differed to a degree that manual intervention was required to merge the two together. Local Authority extents: The state wide dataset was cut into individual local authorities using the Local Authority Boundaries Dataset extracted from the Spatial Information Registry on the 03.06.2013 as the cutting polygons. Each local authority was then created as an individual dataset trimmed to the local authority boundary.

Access and Licensing

Identified Mandate

Yes

Content Source