n and Ranging (LIDAR)
A LIDAR system uses a powerful laser sensor, a GPS receiver, and
an INS unit to record the elevation of the terrain being scanned. The
laser sensor is mounted to the bottom of an aircraft. Once airborne,
the sensor emits rapid pulses of infrared laser light, which are used
to determine ranges to points on the terrain below. The ranges are
processed together with the GPS/INS information to determine the
elevation of the terrain.
Each approach has its advantages and disadvantages. The optimum
approach depends on the nature and specific needs of the mapping
project. LPS Project Manager uses a fully automated approach for
DTM creation. In certain instances, this is an advantage. In other
cases, manual collection of 3D information may be more suitable
(such as in dense downtown urban areas).