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4. SIC_266_267_georectification

Description

NOTE - this record has been superseded by "SIC_266_267_ortho", which describes a more recent orthorectification of the same two images.

Two IKONOS 2004 images (SIC 266 and 267) were chosen as the base images for the AAS2939 change detection project. The reason for choosing these images where that they were the earliest very high resolution (VHR) image with the least amount of cloud cover for which DGPS GCPs are available and identified on the image by Jenny Scott. The importance of having a base image to register all other images to is to allow change detection between images.
The 2004 IKONOS image was resampled to a 0.6m resolution, in order to match the resolution of the Quickbird images (for future rectification and change detection).

Quality

The two images were pansharpened (algorithm unknown) by a contractor in March 2004. The image of the Spit was not included in order to reduce the size of the final image and to reduce processing time.
The two images were then mosaicked together by A. Lucieer in May 2006 using ENVI. The image was orthorectified with the 2002 RADARSAT DEM (metadata ID: heard_dem_radarsat02) and GCPs collected with DGPS by Dr Jenny Scott in 2003/2004 season (metadata ID: heard_island_satellite_image_control_point_identification). Jenny identified 142 DGPS points on the pansharpened IKONOS imagery. After this orthorectification process we compared the corrected image to the original GCPs. Many GCPs did not match the identified features on the image (this was probably caused by the way in which the orthorectification process works).
In November 2007, T. Adams re-identified Jenny's GCPs on the orthorectified image, using the points with a lower confidence rating in order to include as many GCPs as possible. A total of 163 GCPs were used. With these points a triangulation was carried out. The 2004 IKONOS image was warped (i.e. transformed) using a triangulation method with nearest neighbour resampling (to retain the original pixel values).
Finally, the 2004 IKONOS image was resampled to a 0.6m resolution, in order to match the resolution of the Quickbird images (for future rectification and change detection).

Access

A PDF document providing further details is available for download from the provided URL.

Access to the image itself is limited owing to copyright issues. Contact the Australian Antarctic Data Centre for details and further information.

Temporal Coverages

• Start date: 2004-01-17 - Stop date: 2004-01-25

Spatial Coverages

Data Resolution

Science Keywords

• EARTH SCIENCE > SPECTRAL/ENGINEERING > VISIBLE WAVELENGTHS > VISIBLE IMAGERY

Use Constraints

This data set conforms to the CCBY Attribution License (http://creativecommons.org/licenses/by/4.0/).

Please follow instructions listed in the citation reference provided at http://data.aad.gov.au/aadc/metadata/citation.cfm?entry_id=SIC_266_267_georectification when using these data.