Issue link: https://read.dmtmag.com/i/103965
L ight Detection and Ranging (LiDAR) is an optical remote-sensing technology that has grown in use during the last several years. Ideal for emergency management, corridor mapping, forestry, defense and 3-D city modeling, LiDAR is unique in that it can very accurately measure distances by illuminating a targeted area with laser pulses. In terms of its functional use, LiDAR provides users a detailed model of terrain and can be processed to extract bare-Earth models, vegetation, structures and a variety of other natural and manmade features. There now are two common approaches to generate dense surface models: conventional airborne LiDAR and the newer photogrammetric approach, which attempts to mathematically correlate an elevation value for every pixel in a stereo pair. Airborne LiDAR generally is more expensive, but, because it's derived from an active sensor, users can acquire LiDAR night and day. It also generates multiple returns from a single outbound laser pulse, providing vertical details in vegetated areas. Airborne LiDAR is particularly effective at detecting features such as power lines, making this technology virtually indispensable as a management tool for utility companies. Photogrammetrically derived LiDAR, however, is just gaining notoriety. It can produce very dense and accurate surface models even when using historical aerial photos. These point clouds are automatically encoded with the RGB values of the imagery from which they're derived, providing a wealth of information. Unfortunately, airborne LiDAR and photogrammetrically derived point clouds have been underutilized, because many still consider them "emerging technologies," and some governments and larger organizations are hesitant to make the investment in LiDAR. Organizations also need to enhance their IT infrastructure—hardware and software—to meet the needs of storing and processing the large amounts of data. accurate terrain maps, which often are combined with other digital information and field data to analyze flood zones. In addition to federal, state and local governments that delineate floodplain boundaries, insurance companies are utilizing LiDAR data for assessing and managing flood-insurance policies. LiDAR also is ideal for pre- and post-earthquake monitoring. The derived information can be used to determine where buildings have collapsed and where help is needed. The utilities sector is one of the largest landowners in many countries, with mile upon mile of transmissionline corridors. Monitoring such corridors with LiDAR enables these organizations to rapidly determine where vegetation may encroach on a line, causing fires and expensive outages. Utilities also can measure the sag in lines and determine if they're being used to capacity. Ensuring that pipelines, transmission lines and pylons are well maintained and exist where and as designed is another beneficial LiDAR use. Hazards and Utility Use With the applications for geospatial data growing tremendously, LiDAR is quickly becoming ideal for many vertical sectors—from emergency management to forestry and defense. For example, airborne LiDAR is used and, in some cases, mandated for hazard mapping to create highly Imagery/LIDAR Special Issue An image shows a classified LiDAR dataset of a power-line corridor with the ground class turned off. The planimetric view and three profile views are examined, as the user is measuring encroaching vegetation. J A N U A R Y 2 O 1 3 / W W W . G E O P L A C E . C O M 27