TASK NAME: Wayne and Washtenaw Counties 1.0 PPSM LiDAR LiDAR Data Acquisition and Processing Production Task USGS CONTRACT: 07CRCN0006 TASK ORDER NUMBER: G09PD00300 CONTRACTOR: Woolpert, Inc. LiDAR data is a remotely sensed high resolution elevation data collected by an airborne platform. The LiDAR sensor uses a combination of laser range finding, GPS positioning, and inertial measurement technologies.The LiDAR systems collect data point clouds that are used to produce highly detailed Digital Elevation Models (DEMs) of the earth's terrain, man-made structures, and vegetation. This data was collected at a resolution of one point per square meter. The final products include reflective surface, first, last, and at least one intermediate return, a bare earth model, and intensity data in separate files. The reflective surface data represents the DEM created by the laser energy reflected from the first surface encountered by the laser pulse. Some energy may continue beyond this initial surface, to be reflected by a subsequent surface as represented by the last return data. Intensity information is captured from the reflective surface pulse and indicates the relative energy returned to the sensor, as compared to the energy transmitted. The intensity image is not calibrated or normalized but indicates differences in energy absorption due to the the interaction of the surface materials with laser energy, at the wavelength transmitted by the sensor. The bare earth model is created by identifying the returns that fall on the ground surface and by interpolating a surface between these points. In this manner, buildings and vegetation are removed from the bare earth model. This data set does not include bridges and overpasses in the bare earth model as the delineation point for these structures is not reliably discernible in the LiDAR data. This data set is an LAZ (compressed LAS) format file containing LIDAR point cloud data.