USGS Contract Number: 01CRCN0014 In Spring, 2006 Sanborn was contracted by the USGS to survey aprocimately 1,735 square miles of western Whatcom and Skagit Counties in Washington state. All data was collected during ideal conditions (rivers at or below mean level, leaf off, etc.). For this collect two sensors were used: The Leica ALS-50 (High Relief Collection) and Optech 2050 (High and Low Relief Collection). LiDAR calibrations were performed to determine and therefore eliminate systematic biases that occur between the the two sensors. Once the biases were determined they were modeled out. The Leica ALS-50 produced an average point spacing of 1.4 meters. The Optech 2050 produced an average point spacing of 1.3 meters. All points are classified as Class 2 (Ground) which includes water points and any possibly remaining artifacts. Leica ALS-50 LiDAR Acquisition Paramters: Avg. Altitude: 1,500 meters AGL Airspeed: ~120 Knots Scan Freq: 36 Hertz Scan Width Half Angle: 36 Degrees Pulse Rate: 60,000 Hertz Overlap: 44-60% Optech 2050 LiDAR Acquisition Parameters: Avg. Altitude: 1,200 meters AGL Airspeed: ~120 Knots Scan Freq: 30 Hertz Scan Width Half Angle: 40 Degrees Pulse Rate: 50,000 Hertz Overlap: 30-50% This data set is an LAZ (compressed LAS) format file containing LIDAR point cloud data.