Queensland LiDAR data (Cairns Project) - Yarrabah Shire Council (LGA)  

Authors / CoAuthors

Grove, R.

Abstract

These datasets cover approximately 132 sq km along the eastern boundary of the Yarrabah Shire Council and were captured as part of the 2010 Cairns 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 - 0.25 metre contours in ESRI Shape

Product Type

dataset

eCat Id

75948

Contact for the resource

Keywords

• Airborne Digital Data

• AU-QLD

Australian and New Zealand Standard Research Classification (ANZSRC)

• Surface Processes

• Published_Internal

Publication Date

2012-01-01T00:00:00

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

LI_Lineage: ACQUISITION Airborne Laser Scanning (ALS) data was acquired for the Cairns project from a fixed wing aircraft between 2 August 2010 and 1 August 2011. The long capture period was due to the early onset of the wet season and extensive wet periods across northern Queensland. Additionally the narrow coastal strip and sharp rising terrain of the range behind Cairns generated a continual bank of low cloud over the range which restricted aircraft movements for significant periods. Acquisition over tidal areas was undertaken within +/- 2 hours of low tide. GROUND SUPPORT The capture of airborne LiDAR was supported by the establishment of 3 GPS base stations which operated during the acquisition of LiDAR. These base stations collected event matched L1/L2 dual frequency GPS data at 1sec epochs. The main GPS base station was established on a known survey mark at the Cairns airport from which the aircraft operated however due to the extended range from the airfield to northern and southern project areas, additional base stations were established at the RPS office in Port Douglas for the northern areas and at Innisfail airfield in the south. In addition to the GPS base stations, surveyors measured 539 control points in 32 clusters within the project area. These survey clusters consisted of 54 Horizontal points collected at the extremities of elevated features such as building and 485 Vertical points along ground based hard surfaces such as roads, footpaths and car parks. 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 Cairns airport and at Innisfail airstrip on a known survey mark. When flying the northern project area over Port Douglas, the ground survey team established a base station at their office in Port Douglas. 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 2.04 points per square meter. Specific planning was also undertaken to ensure that LiDAR capture in tidal zones was collected 2 hours either side of low tide and this was achieved by referencing the Bureau of Meteorology tide times. 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.

Parent Information

Extents

[-17.1829, -16.86734, 145.823516, 145.966287]

Reference System

GDA94 / MGA zone 55 (EPSG:28355)

Spatial Resolution

Service Information

Associations

Downloads and Links

Source Information

These datasets cover approximately 132 sq km along the eastern boundary of the Yarrabah Shire Council and were captured as part of the 2010 Cairns 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 - 0.25 metre contours in ESRI Shape