Authors / CoAuthors
Abstract
A LiDAR Digital Elevation Model (DEM) was constructed for the eastern half of Christmas Island from ground heights obtained from an airborne laser scanning survey flown September 2000 by AAM Surveys Pty Ltd. Shiny colour drape images of the ground surface were produced from this DEM in Geoscience Australia by processing the set of last returns (mostly ground heights), and the GPS location in MGA (GDA94) units of each height. Point shape files and Arc grids were also created from the raw data by GA. Laser DEM Grids consists of 27 digital elevation model grids. The Arcview grid files were constructed from the "Airborne Laser Scanning" shapefiles. The Laser DEM grid tiles cover the eastern portion of the Christmas Island. Each grid contains the height in metres of the ground surface with a value every one metre on the ground.
Product Type
dataset
eCat Id
66248
Contact for the resource
Custodian
Point of contact
Cnr Jerrabomberra Ave and Hindmarsh Dr GPO Box 378
Canberra
ACT
2601
Australia
Keywords
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- DEM topographic
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- CX
- Australian and New Zealand Standard Research Classification (ANZSRC)
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- Topology
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- Published_Internal
Publication Date
2008-06-19T00:00:00
Creation Date
Security Constraints
Legal Constraints
Status
Purpose
Maintenance Information
notPlanned
Topic Category
elevation
Series Information
Lineage
AAM Surveys Pty Limited provided 6 pages of data documentation at the time of handover. Geoscience Australia documented the processing undertaken within GA upon receipt from AAM, noted some interesting features observed and created ANZLIG metadata sheets. In 2000 AAM Surveys Pty Ltd. was commissioned by the Commonwealth to fly an airborne laser scanning survey of Christmas Island (AAM_Laserdem_readme). Raw data was tiled to shapefiles from which DEM tiles were interpolated. Each DEM grid was interpolated from the corresponding '2000 Airborne Laser Height' shapefile in Arcview, and contains the height in metres of the ground surface. This was done by firstly interpolating a surface from each shapefile using Arcview. The inverse distance weighted (IDW) method of interpolation was chosen to construct the surfaces. IDW interpolation method was chosen because this method minimized noise in the data associated with joins in the laser scanner flight paths. Another advantage of using the IDW method was that it did not produce spikes in the data which were present when the spline method of interpolation was used (Spline spike). The number of nearest neighbours used in the IDW method was set at 7, and power at 3. This combination was found to provide maximum detail in the images produced using the DEM grids, whilst still minimizing image noise due to flight path joins (IDW tests). The output and cell size was set to one metre square. Each surface interpolated from the 27 shapefiles was then converted to a grid in Arcview. The result was 27 DEM grid files containing ground surface heights in metres.
Parent Information
Extents
[-10.571, -10.412, 105.621, 105.715]
Reference System
Spatial Resolution
Service Information
Associations
Source Information
Source data not available.