Cocos (Keeling) Islands GIS
Cocos Island Canopy Height Model 2011
Title Cocos Island Canopy Height Model (CHM) 2011
Custodian Geoscience Australia
Jurisdiction Australia
Abstract The CHM grid covers the whole of the Cocos (Keeling) Islands. It was provided by AAM Pty Ltd in 1km tiles which were then joined together using ESRI ArcMap. Each grid cell (2m x 2m) contains the maximum vegetation height in metres derived from the 2011 LiDAR aerial survey data.
Search Word(s) PHOTOGRAPHY AND IMAGERY Digital Elevation Model
Geographic Extent Name(s) Cocos (Keeling) Islands Edition 1 2010 1:25000 - Geoscience Australia GEOCAT 70146
Data Currency
Beginning Date 8 August 2011
Ending Date 16 August 2011
Dataset Status
Progress Complete
Maintenance and Update Frequency Not planned
Stored Data Format DIGITAL - TIFF grid. (Also stored as ESRI Raster)
Available Format Type DIGITAL - TIFF (Also available as ESRI Raster)
Access Constraint None
Data Quality
Lineage In 2011 AAM was commissioned by the Commonwealth to fly an airborne laser scanning survey of Cocos (Keeling) Islands. The survey was carried out using a fixed wing aircraft between the 8th and 16th of August 2011. All data was captured within approximately 2 hours of low tide (link to tide xls in height_data/source). During this period tides ranged from 0.4m to 1.3m.
AAM classified the raw LiDAR points the following classes using a single algorithm across the project area.

0 Unclassified - Created, never classified
1 Default - Unclassified
2 Ground - Bare ground
3 Low vegetation - 0 - 0.3m (essentially sensor 'noise')
4 Medium vegetation - 0.3 - 2m
5 High vegetation - 2m >
6 Buildings, structures - Buildings, houses, sheds, silos etc.
7 Low / high points - Spurious high/low point returns (unusable)
8 Model key points - Reserved for 'model key points' only
9 Water - Any point in water
10 Bridge - Any bridge or overpass
11 not used - Reserved for future definition
12 Overlap points - Flight line overlap points

Canopy height was generated by subtracting the ground height from the first laser return classified as vegetation. A canopy height model (CHM) was provided to Geoscience Australia as 2km by 2km ESRI grid tiles. These tiles were then joined to create a CHM (TIFF) that covers the full extent of the Cocos (Keeling) Islands. Each grid cell, 2m by 2m, contains the height in metres of the vegetation canopy. As a guide, the data is vertically accurate to 15cm and horizontally accurate to 30cm. For a detailed description of the survey accuracy see the AAM Survey Report. The canopy height model grid file was generated in GDA94 MGA zone 47 and has been left in this projection.
Positional Accuracy As a guide, the DEM data is vertically accurate to 15cm and horizontally accurate to 30cm.
Attribute Accuracy Not Relevant
Logical Consistency Not Relevant
Completeness Complete
Contact Information
Contact Organisation Geoscience Australia
Contact Position Keith Porritt
Mail Address Cnr Jerrabomberra Ave and Hindmarsh Drive
State A.C.T
Country Australia
Postcode 2601
Telephone (02) 6249 9479
Facsimile (02) 6249 9971
Electronic Mail Address
Metadata Date 24-4-2012
Additional Metadata
Projection UTM (GDA94) zone 47s