Cocos Island - DEM - 2011
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 and covers the whole of the Cocos (Keeling) Islands. All data was captured within approximately 2 hours of low tide. During this period tides ranged from 0.4m to 1.3m.
AAM classified the raw LiDAR points into ground and non-ground points using a single algorithm across the project area. The raw LiDAR points in the .las format were provided to Geoscience Australia along with 1km by 1km ESRI grid tiles generated by interpolation from the points. The tiles were then joined to create a DEM (TIFF) that covers the full extent of the Cocos (Keeling) Islands. Each cell, 1m x 1m, in the grid contains the height in metres of the ground surface.
As a guide, the DEM data is vertically accurate to 15cm and horizontally accurate to 30cm. A control survey was carried out by Whelans. Manual checking and editing was carried out by AAM to improve accuracy. Positional accuracy has been checked by Geoscience Australia and was found to match the ground surface well. The DEM grid file was generated in GDA94 and has been converted to UTM WGS 84 zone 47s to fit the rest of the Cocos GIS data. Vertical data was collected in the Cocos Keeling Island Height Datum (CKIHD).