Authors / CoAuthors
Grove, R.
Abstract
These datasets cover approximately 295 sq km over the South East sector of the Toowoomba Regional Council and were captured as part of the 2011 Toowoomba LiDAR project. This project, undertaken by Terranean Mapping Technologies on behalf of the Queensland Government captured highly accurate elevation data using LiDAR technology. Available dataset formats (in 1 kilometre tiles) are: - Classified las (LiDAR Data Exchange Format where strikes are classified as ground, vegetation or building) - 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 GRID grid - 0.25 metre contours in ESRI Shape
Product Type
dataset
eCat Id
74453
Contact for the resource
Custodian
Custodian
Lev 2, Landcentre, Cnr Main and Vulture GPO Box 2454
Woolloongabba
QLD
4001
Australia
Point of contact
Cnr Jerrabomberra Ave and Hindmarsh Dr GPO Box 378
Canberra
ACT
2601
Australia
Keywords
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- GIS Dataset
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- AU-QLD
- Australian and New Zealand Standard Research Classification (ANZSRC)
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- Earth Sciences
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- Published_Internal
Publication Date
2012-01-01T00:00:00
Creation Date
Security Constraints
Legal Constraints
Special, MOU, etc.
Access - restricted
Use - license
Status
Purpose
Maintenance Information
unknown
Topic Category
geoscientificInformation
Series Information
Lineage
Airborne Laser Scanning (ALS) data was acquired for the Toowoomba project from a fixed wing aircraft between 19 July 2011 and 19 December 2011. Several reflys were required due to terrain and turbulence issues. Military operations running out of RAAF Base Amberley also restricted movements in the northern sections of the project area. GROUND SUPPORT During the survey a total of 824 points were surveyed across 28 ground control check clusters distributed evenly throughout the Toowoomba and Toowoomba South project areas. Each check site consisted of a cluster of 4 horizontal and approx 16 vertical points. The survey was carried out utilizing Trimble R8 GNSS receivers and referenced to the state permanent survey mark network established with GDA94 coordinates and accurate AHD levels. The survey achieved an accuracy of 0.05m within 1 sigma. In addition to the check point clusters, 16,305 vertical check points were measured using a Trimble R8 GNSS receiver mounted on our ground survey vehicle. The Real Time Kinematic (RTK) Check points were measured at approximately 50m intervals on roads while travelling between check point clusters. Any points with an error greater than 0.05m were rejected. As with the static control the RTK points were used to validate the vertical accuracy of the LiDAR data. During the survey a total of 50 permanent survey marks and 7 SunPOZ stations were referenced. DATA PROCESSING Aerial Control: Aerial control was maintained via the LiDAR system's IMU and GPS base station. Due to the size of the project area three GPS base stations were used during LiDAR flight operations. Aircrew established a base station at Archerfield, Gold Coast and Toowoomba airports on known survey marks. Each GPS base station was referenced to local PSM's using a dual frequency L1, L2 Trimble 5700 receiver. The data from these base stations was event matched to the airborne IMU & GPS data and used to calculate the flight trajectories. AUPOS positional data was also used to validate the accuracy of the airborne positioning system and to provide a back up reference station for GPS processing. LiDAR Capture: Detailed flight planning was undertaken to ensure that LiDAR strikes conformed to the project specifications of a minimum of 2 points per square meter over the project area. The actual LiDAR strikes exceed this mark with 2.03 points per square meter. Strip Levelling, Classified Data and Filtering Data: The LiDAR point cloud for each survey strip was generated from the full waveform LiDAR signal and translated from the temporal/angular units to geographic coordinates by reference to the calculated flight trajectories. Residual errors were measured using the 'boot control' points at the start and end of each sortie. This process provided an initial quality check and an opportunity to enhance the accuracy of the LiDAR data. The LiDAR strips were levelled and combined, and then adjusted to ground control to produce a set of LAS files with the required spatial accuracy. The process provided a high level of confidence in the internal integrity of LiDAR heights, and a sound assessment of the quality of GPS/IMU data. The majority of data was processed without any issue however there were several technical delays due to steepness of terrain and density of vegetation affecting LiDAR returns which required re-flies to correct holes in the data. Elevation Models: From the LiDAR data, a 1 metre grid Digital Elevation Model (DEM) was produced for general use and a Thinned Digital Terrain Model (DTM) which is ideally suited to engineering design software. 0.25m contours were also produced.
Parent Information
Extents
[-27.9671, -27.671, 151.9629, 152.2293]
Reference System
GDA94 / MGA zone 56 (EPSG:28356)
Spatial Resolution
Service Information
Associations
Downloads and Links
Source Information
These datasets cover approximately 295 sq km over the South East sector of the Toowoomba Regional Council and were captured as part of the 2011 Toowoomba LiDAR project. This project, undertaken by Terranean Mapping Technologies on behalf of the Queensland Government captured highly accurate elevation data using LiDAR technology. Available dataset formats (in 1 kilometre tiles) are: - Classified las (LiDAR Data Exchange Format where strikes are classified as ground, vegetation or building) - 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 GRID grid - 0.25 metre contours in ESRI Shape