Queensland LiDAR data (Mackay Project) - Mackay Regional Council (LGA) - 2009  

Authors / CoAuthors

Grove, R.

Abstract

These datasets cover approximately 4260 sq km along the eastern sector of the Mackay Regional Council, some offshore island including over all of Carlisle and Brampton Islands and are part of the 2009 Mackay LiDAR capture project. This project, undertaken by Fugro Spatial Solutions Pty Ltd on behalf of the Queensland Government captured highly accurate elevation data using LiDAR technology. Available dataset formats (in 2 kilometre tiles) are: - Classified las (LiDAR Data Exchange Format where strikes are classified as ground, non-ground or building) - 1 metre Digital Elevation Model (DEM) in ASCII xyz - 1 metre Digital Elevation Model (DEM) in ESRI ASCII grid - 0.25 metre contours in ESRI Shape

Product Type

dataset

eCat Id

74164

Contact for the resource

Keywords

• DEM topographic

• AU-QLD

Australian and New Zealand Standard Research Classification (ANZSRC)

• Topology

• Published_Internal

Publication Date

2011-01-01T00:00:00

Creation Date

Security Constraints

Australian Government Security ClassificationSystem    

Classification - unclassified

Legal Constraints

Special, MOU, etc.

Access - restricted

Use - license

Status

Purpose

Maintenance Information

unknown

Topic Category

elevation

Series Information

Lineage

Airborne Laser Scanning (ALS) data was acquired for the Mackay project from a fixed wing aircraft between 29 April 2009 and 09 June 2009. Acquisition over tidal areas was undertaken within +/- 2 hours of low tide. DATA PROCESSING The sensor trajectory and ALS range measurements were integrated to produce the ALS point cloud. Once point cloud data was imported into a tiled format, each tile was filtered to isolate the ground surface returns from non ground surface returns. Areas where flight lines overlap were isolated and the ground surface models from individual flight lines compared to one another. A least squares surface matching application was employed to solve small systematic differences in sensor position (namely height) and orientation (namely roll). The differences solved for were in the order of the expected precision of the sensor trajectory, namely +/0.075m for height and +/-0.005 degrees for roll. Elevations of check points were compared with those derived by construction a ground surface model from the ALS ground surface model at the given 2D location. Fugro Spatial Solutions Pty Ltd aim is to select those points that are part of a clean ground surface, which might not be 100% of the ground hits. This results in a cleaner dataset, without compromising on terrain detail and accuracy. Ground filtering algorithms, tailored for this project, data type and terrain type, are applied to the full dataset. 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 is 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. Classified Point Cloud with automatically classified buildings: The full LiDAR point cloud, consisting of ground, automatically classified buildings and the rest of the point cloud. Bare_Earth_DEM_1m: A 1m DEM has been generated from the LiDAR ground surface. The method of deriving the height for each grid point is by linear triangulation between the three nearest LiDAR ground points. Contours: From the ground dataset, triangles are being built. At 0.25m intervals in height, points or interpolated points on triangle edges with that same height are being connected using slightly smoothed curved lines. The lines for each height interval are then merged to become the final contours. Note: Returns on water have not been removed from the (classified) point clouds. Gridded datasets have been interpolated across voids (up to 500m in diameter) caused by either no-return due to water bodies, or removal of buildings, vegetation or other above ground features. Contour datasets are interpolated across voids, and contours across waterbodies have not been removed/clipped. Above ground datasets only start at 30cm above the classified ground surface, to avoid low grasses/system noise to become part of this above ground dataset. All data has been cut into 2km tiles, where the file name prefix corresponds with the Upper Left coordinate of the 2km block.

Parent Information

Extents

[-21.5162, -20.531, 148.4675, 149.34]

Reference System

GDA94 / MGA zone 55 (EPSG:28355)

Spatial Resolution

Service Information

Associations

Downloads and Links

Source Information

These datasets cover approximately 4260 sq km along the eastern sector of the Mackay Regional Council, some offshore island including over all of Carlisle and Brampton Islands and are part of the 2009 Mackay LiDAR capture project. This project, undertaken by Fugro Spatial Solutions Pty Ltd on behalf of the Queensland Government captured highly accurate elevation data using LiDAR technology. Available dataset formats (in 2 kilometre tiles) are: - Classified las (LiDAR Data Exchange Format where strikes are classified as ground, non-ground or building) - LiDAR ground returns in XYZ format - LiDAR non-ground returns in XYZ format - 1 metre Digital Elevation Model (DEM) in ASCII xyz - 1 metre Digital Elevation Model (DEM) in ESRI ASCII grid - 1 metre Digital Elevation Model (DEM) in ESRI binary grid - 0.25 metre contours in ESRI Shape