Terrestrial-Based Lidar Beach Topography of Fire Island, New York, June 2014

Survey and Lidar Overview

Terrestrial light detection and ranging (T-lidar) system technology uses laser pulses that are sent from the instrument and reflected off objects within its field of view. The instrument calculates the distance of each returned laser pulse based on the velocity of the pulse, while also logging the vertical and horizontal angle of each pulse.

For this survey, the T-lidar instrument was mounted on top of a truck, facing toward both the front and driver’s side of the truck, and scanned the beach surface at speeds of less than 16 kilometers (km) per hour. Nearly 35 km of beach, from the western boundary of Fire Island National Seashore to approximately 6 kilometers east of the Wilderness Breach, were surveyed in a series of two alongshore transits designed to fully capture the upper and lower sections of the beach, and also include an area of overlap used to verify system accuracy and precision (figs. 1 and 2).

Figure 2. Three dimensional rendering of high-resolution elevation point-cloud data collected using terrestrial light detection and ranging (T-lidar) technology at Fire Island, New York. This image is an example of the data density and coverage acquired during a typical survey. The data shown here do not reflect post-processing and editing procedures. [larger version]