|2008 USGS New Jersey Lidar: Somerset County
||These data support the general geospatial needs of the USGS and other federal agencies.
LiDAR data is remotely sensed high-resolution elevation data collected by an airborne
collection platform. By positioning laser range finding with the use of 1 second GPS
with 200hz inertial measurement unit corrections, Airborne 1's LiDAR instruments are
able to make highly detailed geospatial elevation products of the ground, man-made
structures and vegetation. The LiDAR flightlines for this project were planned for
a 50% acquisition overlap. The nominal resolution of this project without overlap
is 1.203m, with a 0.90m resolution with the 50% overlap, assuming a normal distribution.
Two returns were recorded for each pulse in addition to an intensity value. GPS Week
Time, Intensity, Flightline and number attributes were recorded for each LiDAR point.
Positional values were recorded to the centimeter level, while GPS is recorded to
a 10th of a millisecond. Scan angle was recorded to the nearest angle, Intensity is
recorded as a 12 Bit dynamic range value and echo is recorded as a numeric value from
0 to 256. The data was originally provided as random points, in LAS v1.1 format, classified
according to the following codes: Class 1 Non-ground/Extracted Features Last Pulse
Class 2 Bare Earth Ground Features Last Pulse Class 3 Extracted Features First Pulse
Class 4 Bare Earth Ground Features First Pulse It should be noted that Class 3 and
4 are not ASPRS classes but since this data is a two pulse system, this is the most
efficient format to separate the pulses and classification process. The data was reclassified
into 2 distinct classifications: Class 1 Non-ground/Extracted Features First and Last
Pulse Class 2 Bare Earth Ground Features First and Last Pulse