LiDAR is a method of remote sensing that uses laser pulses to gather information about the surface of the earth. Each laser has multiple returns to the sensor which are displayed as a cloud of points.
LiDAR data is often collected from a fixed wing plane or helicopter. The height the survey is flown at and the density of flight lines depends on the required resolution and point cloud density. This point cloud is then used to “paint a picture” of the earth. During processing different features can be pulled out of the data such as a ground dem, building tops, foilage etc. For more information on how to do this refer to this tutorial.
To gather and maintain the LiDAR information requires that detailed positional data be collected during the survey. The positional data must then be corrected using a base station (gps set on a known location that collects satellite corrections which can then be applied to the positional data set). The sensor passes the LiDAR information into a computer which also collects and stores the GPS data. An operator must be connected with the logging computer to tell the sensor when to start collecting data.
For a lot more detail, check out this website. https://www.e-education.psu.edu/geog481/
To look at a case study going through this process, check out this portfolio piece
LiDAR files are collected as raw files (laser, IMU,) and then converted into *.las files and can be viewed using microstation software integrated with terrasolid products. Each *.las file produced represents one flightline.