Tennessee Valley Authority and LiDAR
Light detection and ranging (LiDAR) is a remote sensing method that uses transmitted and received laser pulses from a sensor to determine distances from sensor to object. By collecting up to millions of laser return points per second, and with the assistance of complex modeling software, LiDAR “point clouds” are produced that give a three dimensional model as it relates to the sensor. The Tennessee Valley Authority (TVA) utilizes a host of LiDAR survey methods to efficiently, effectively, and accurately manage power system resources, including sub-stations, dams, and power lines.
The TVA uses LiDAR sensors attached to helicopters and trucks, as well as mobile, tripod mounted base stations to create three dimensional point clouds from which a variety of tasks can be completed; management of vegetation infringing on power lines, determining movement of transmission structures over time, understanding erosional forces that may impact TVA infrastructure, creating digital surface models of study areas, and modeling TVA structure interiors are all related to LiDAR data collection. The quickest and easiest to field LiDAR sensor for the TVA is a Reigl VP-1 long range LiDAR sensor attached to one of their fleet helicopters. Ownership of their own helicopter shortens response times, as well as limitations to availability, allowing rapid response for scanning of any of the TVA’s approx. 22,000 miles of transmission lines. The TVA uses ESRI’s Network Analysis tools in routing flight patterns, in an effort to collect data for transmission line potential locations, vegetation infringement, and management of infrastructure. |
Mobile LiDAR sensing is also completed via terrestrial scanning from sensors attached to a four wheel drive truck, manned by two man teams who must drive and manage software, respectively. Data collection via this method allows for sensing below tree cover, and gives better insight into surface features than aerial sensors have the potential for.
Stationary terrestrial scanning is typically completed via Leica ScanStations, allowing for point dense capture of interior surfaces, as well as more compact study areas. Integrated HTML based software allows for viewing of output point clouds as well as captured photogrammetric images in a simple and intuitive platform. The TVA encounters a number of unique problems when managing the massive datasets captured via the aforementioned methods. Transmission of point cloud data, which is captured at approximately 250 GB/hour for the Reigl systems, is completed via physical transfer of hard drives as opposed to web transfer. This is due to limitations in efficiency of transfer of datasets at such a massive scale; it is simply more efficient and cost effective to ship a hard drive between different TVA facilities as opposed to relying on web transfer. |