Christmas Island Laser DEM Shiny Colour Drape Images - 2000

In 2000 AAM surveys Pty Ltd. was commisioned by the commonwealth to fly an airborne laser scanning survey of Christmas Island. Raw data was tiled to shapefiles then converted to grids from which the LaserDEM shiny colour drape images were made. A wet look shiny colour drape algorithm was applied to each of the 27 '2000 LaserDEM Grid' tiles using ERMapper®, and the results saved as Tagged Image File Format (TIFF) images in both 8 bit (256 colour) and 24 bit (16 million colour) formats. Each wet look shiny colour drape DEM tile was also saved as an Enhanced Compressed Wavelet (ECW) image. The colour range has been optimized for each individual tile to provide maximum information. A consequence of this is that colours may not match at adjoining edges. Each image tile has a 1m pixel size. Most inland tiles and several coastal tiles are 2km x 2km in area. The inland tiles located at the edge of the flight path extent, and most coastal tiles, deviate from the 2km x 2km standard tile size as adjacent tiles have been merged to minimize areas of no data and ocean. The advantage of the 2000 Laser DEM over previous DEMs is that the laser scanner used to produce the DEM was able to penetrate vegetation. Previous DEMs included the height of tree tops rather than the ground elevation obscured by vegetation. The 2000 Laser DEM therefore provides a more accurate and detailed picture of the ground surface of Christmas Island. Topographic features overgrown with vegetation are apparent on the 2000 Laser DEM shiny colour drape images, where in previous versions of CIGIS DEMs they were not.

AAM Surveys Pty Ltd Indicate that the horizontal accuracy of the airborne laser scanner is between 0.3 and 0.5 metres.

LaserDEM shiny colour drape image tiles have been produced for the eastern half of the island only, as only the eastern half of the island has been surveyed with the laser scanner.

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