Imagine your standard Laser pointer flicking on and off; now imagine that pointing down from a helicopter flickering at a 100 000 times a second. With an accurate stopwatch measuring the time from pressing the ON button to the time the dot hits the ground, and knowing the speed of light, you can calculate the distance from the ground. Now imagine that laser hitting a spinning mirror like a grocery-store bar code scanner and you could keep track of the mirror angle of each flicker. You are now spraying the ground with LiDAR.
Knowing the angle and time information you can create a point in space with a three dimensional coordinate. To create a point cloud (Millions of Points in Space) you add finely tuned GPS data and compensate for aircraft pitch, roll, and yaw.
Scott Lehr, BA, ADiGISA, GeoDigital Acquisition Group
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