LiDAR technology emits a pulse of light and measures the time it takes the light to reflect off of a surface and back to the LiDAR. The time between emitting and receiving the light signal indicates the distance that the light pulse traveled before it bounced back to the LiDAR. When LiDAR is used to survey an area, it is possible to create a detailed map of the elevation of the land in the survey area. These maps are called Digital Elevation Models (DEMs). If surveys are repeated over the same area at two different times, it is also possible to calculate the amount of sand that moved from one location or another within the survey area. This contributes to more accurate predictions of the frequency and extent of coastal inundation and the potential effects of sea-level rise on Oʻahu.
info: http://www.soest.hawaii.edu/pgf/
Google Earth KML: http://pacioos.org/kml/lidar.kmz