Laser DEM Grids consists of 27 digital elevation model grids.  The Arcview grid files were constructed from the 'Airborne Laser Scanning' shapefiles.  The Laser DEM grid tiles cover the eastern portion of the Christmas Island.  Each grid contains the height in metres of the ground surface with a value every one metre on the ground.

In 2000 AAM Surveys Pty Ltd. was commissioned by the Commonwealth to fly an airborne laser scanning survey of Christmas Island (AAM_Laserdem_readme).  Raw data was tiled to shapefiles from which DEM tiles were interpolated.  Each DEM grid was interpolated from the corresponding '2000 Airborne Laser Height' shapefile in Arcview, and contains the height in metres of the ground surface.   This was done by firstly interpolating a surface from each shapefile using Arcview.  The inverse distance weighted (IDW) method of interpolation was chosen to construct the surfaces.  IDW interpolation method was chosen because this method minimized noise in the data associated with joins in the laser scanner flight paths.  Another advantage of using the IDW method was that it did not produce spikes in the data which were present when the spline method of interpolation was used (Spline spike).  The number of nearest neighbours used in the IDW method was set at 7, and power at 3.  This combination was found to provide maximum detail in the images produced using the DEM grids, whilst still minimizing image noise due to flight path joins (IDW tests).  The output and cell size was set to one metre square. Each surface interpolated from the 27 shapefiles was then converted to a grid in Arcview.  The result was 27 DEM grid files containing ground surface heights in metres.