Cocos (Keeling) Islands GIS
Satellite Imagery
Metadata

Dataset
Title Satellite Imagery
Custodian Geoscience Australia (GA)
Jurisdiction Australia
Description
Abstract Pan-sharpened satellite imagery of the Cocos (Keeling) Islands recorded using the QuickBird Digital Globe satellite, taken over the islands in November 2003. Each pixel represent 0.6m.
Search Word(s) PHOTOGRAPHY AND IMAGERY Imagery
PHOTOGRAPHY AND IMAGERY Satellite
Geographic Extent Name(s) Cocos (Keeling) Islands Edition 1 2010 1:25000 - Geoscience Australia GEOCAT 70146
Data Currency
Beginning Date 05NOV2003
Ending Date 07NOV2003
Dataset Status
Progress Complete
Maintenance and Update Frequency as required
Access
Stored Data Format DIGITAL - ERMapper ECW & TIFF/TFW
Available Format Type DIGITAL - ERMapper ECW & TIFF/TFW
Access Constraint Please read the license agreement for limits to the access of the satellite imagery included on this CD. If you are unsure whether you are a registered user please consult this table.
Data Quality
Lineage

Quickbird satellite imagery of Cocos Islands was commissioned by the Department of Environment and Heritage in mid 2003 and supplied to the Australian Government by DigitalGlobe in November 2003. The Quickbird satellite recorded reflectance data of the islands in the red, green, blue, near infra-red and panchromatic bands, in 11 bit format. All sharpened imagery has a resolution of 0.6m/pixel.

Geoscience Australia was supplied with the full multi-spectral data for the Cocos (Keeling) Islands in the form of an 8 bit TIFF image containing the red, green, blue and near infra-red bands. The panchromatic band was also supplied as an 8-bit TIFF. Digital Globe undertook pan-sharpening of the satellite imagery, in the process dividing the imagery into four sections. Four 8-bit pan-sharpened TIFFs, one for each of the four sections, containing the red, green and blue bands was supplied to GA. Each pixel on the pan sharpened imagery represents 0.6m. Further details regarding the satellite imagery can be viewed in the full DigitalGlobe documentation 'CocosGIS\data\sat_imagery\ DigGlobe_productguide_2003.pdf'.

All satellite images were supplied to Geoscience Australia in WGS84 Geographics. GA joined the images using ER Mapper 6.4 and then using the ER Mapper Geocoding Wizard GA reprojected the full image into UTM GDA94. [Previously due to restrictions in computer processing power and a file size limit in ER Mapper 6.3 the four pan sharpened images were reprojected separately which led to gaps appearing at the joins in the four sections.

Also received from Digital Globe was a satellite image of North Keeling Island. As with the other satellite imagery this was supplied as a multi-chromatic, a pan-chromatic image and a pan sharpened the image. Using the ER Mapper Geocoding Wizard Geoscience Australia reprojected the image into UTM GDA94.

DigitalGlobe advise that the positional accuracy of the imagery is +/-14.7m RMSE. Due to this low level of positional accuracy, an x y shift was also applied to more accurately position the imagery by correlation with the lodged cadastre on screen as follows:

  • Before cadastral re-alignment (see cadastre section of manual):
    • 16.9m East
    • 6.9m South
  • After cadastral re-alignment
    • 2.4m West
    • 3.14m South

This shift brought the imagery inline with the current cadastre and reprojected orthophotography.

Due to disk space limitations these images are stored in ECW (Enhanced Compressed Wavelet) format. The main Cocos island group is stored in the 'CocosGIS\data\sat_imagery\ecw' directory under the filename of 'cocos_satim.ecw'. The North Keeling Island ECW is located in the same directory with the filename 'nth_keeling.ecw'

Full notes from Cocos GIS 2003 release

The satellite imagery was supplied in WGS84 Geographics. Due to limitations of software and hardware Geoscience Australia projected the four 8 bit pan-sharpened TIFF images of the main atoll into UTM WGS84. The four reprojected TIFFs were then joined. As a result gaps between the four sections of imagery were apparent.

The image in it's entirety was saved as an Enhanced Compressed Wavelet (ecw) image, where each pixel represented 0.6 metres. Nineteen 1km x 1km TIFF images, and two 1.5km x 1km TIFF images covering Home, West and Direction island were created from the image and are included with the 2004 release of the GIS.

Geoscience Australia shifted the ecw image (x +16m, y - 7m) to match the more accurately positioned 2003 cadastre shapefile and the orthophotography. The TIFFs over Home and Direction Isalnds (x +16m, y-7m) and West Island (x +14m, y -9m) were also shifted to align with the orthophotography and 2003 cadastre.

Positional Accuracy The satellite imagery has been shifted to match the 2003 cadastre. Positional accuracy of the satellite imagery therefore mimics the accuracy of cadastre2003.shp.
Attribute Accuracy not applicable
Logical Consistency not applicable
Completeness Complete
Contact Information
Contact Organisation Geoscience Australia
Contact Position Territories
Mail Address GPO Box 594, Canberra, A.C.T 2601
Locality 111 Alinga St, Canberra
State A.C.T
Country Australia
Postcode 2601
Telephone (02) 6249 9479
Facsimile (02) 6274 8040
Electronic Mail Address Sean.Hambrook@ag.gov.au
Metadata Date 18-02-2005
Additional Metadata
Projection UTM (GDA94) zone 47 S