LIDAR

Text author: Luděk Krtička Last update: 2026-04-10

Lidar (Light Detection and Ranging) is a remote-sensing method that measures distances by sending laser pulses and recording the time until the reflected signal returns. In airborne lidar, the sensor is mounted on an aircraft, helicopter, or drone, and the measured distances are combined with positioning and orientation data to produce a dense 3D point cloud of the terrain and objects on it.

After collection, lidar data are processed into a point cloud whose points may include attributes such as x, y, z position, return number, intensity, time, and classification. Common classes include ground, water, vegetation, and buildings. Standard deliverables derived from lidar include bare-earth DEM/DTM, DSM, contours, hillshade/shaded relief, intensity images, and sometimes height-above-ground or vegetation products.

Water needs special treatment. With ordinary topographic lidar, returns from water surfaces are often inconsistent and are usually not sufficient to define water surfaces directly, so classification and hydro-flattening are commonly used. Bathymetric lidar, using a different wavelength, can penetrate clear water.

The accuracy of products obtained from airborne laser scanning data depends on the amount of points obtained from a given location and the processing method. Collection densities currently range from one to several tens of points per square metre, resulting in quite incredible height accuracy of a few centimeters.

For orienteering mapping, lidar is especially valuable because it supports the creation of detailed terrain models, contours, hillshade, and other basemap layers that help the mapper detect subtle landforms that may be hard to see in aerial imagery alone.

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References

National Oceanic and Atmospheric Administration (NOAA) Coastal Services Center. 2012. “Lidar 101: An Introduction to Lidar Technology, Data, and Applications.” Revised. Charleston, SC: NOAA Coastal Services Center. lidar-101.pdf