> LIDAR: An airborne laser scanner (ALS) is mounted to a helicopter skid pad. Flying with pre-determined guidelines, including altitude, flight path and airspeed, the ALS pulses the terrain with more than 16 laser beams per square metre during flights. The time the laser pulse takes to return to the sensor determines the elevation of each individual data point.
The data downloaded from the ALS is calibrated and creates a 3D model of the information captured during the flights. In order to negate tree foliage and manmade obstacles from the data, any sudden and radical changes in ground height are mapped out, with technicians who have models of the terrain fine-tuning the thresholds in processing these data points. Once completed, the final 3D model is handed over to the archaeologists for analysis, which can take months to process into maps.
It's so interesting that technology advancements must often precede discovery and thus are part and parcel (imo) of the discovery process. The same can very much also be said for medical and biological science - e.g., MRI and associated analytic techniques.