NWT RESEARCH DATABASE

Regions: Inuvialuit Settlement Region

Tags: physical sciences, geological mapping, remote sensing, topography, landscape assessment, LiDAR survey

Project Description: The objective of the proposed survey is to obtain a high resolution, highly accurate, three-dimensional topographic image of the study area. The data collected from the survey will be used to assist in planning for construction of winter and all-season roads and airstrip for the proposed Parsons Lake natural gas field development program. Terra Remote Sensing Inc. has been contracted to perform the LiDAR survey. The total project size is 121 sq. km and will involve two lines to survey the area. The survey flight height will be 1,000m, with nine verification targets placed at three base stations. The total flight time over the study area will be twenty-two hours. The total duration of time to be spent on the ground will be twelve hours. The targets will consist of a white material and will be removed following the aerial survey. During the setting of the targets, a GPS survey will be conducted to obtain target locations. In basic terms, a pulsating laser (pulsating at 50,000 times a second) is directed out of the aircraft by a multifaceted rotating mirror. When an earth feature intercepts the laser pulse, it is reflected back. Laser pulses reflect off any solid object below the aircraft such as ground surface, trees, electrical transmission lines and towers, roadways, building etc. The time interval between the laser pulse leaving the aircraft and the return of the terrain-reflected-pulse back to the sensor is measured precisely. In post-flight data processing, the LiDAR time interval measurements are converted to distance and subsequently referenced to the aircraft's position - latitude, longitude, and altitude. The aircraft pitch, roll and yaw are also measured. This data is used to calculate the laser beam exit geometry. By combining the LiDAR, GPS, and flight data, very accurate, high resolution, three-dimensional digital terrain models of the ground can be developed. Laser pulses will not penetrate water and generally will not reflect back to the sensor except at NADIR, the earth position directly below the laser. NADIR returns from water will depend on the surface turbulence of the water. LiDAR data collected and processed over bodies of water will typically produce well-defined data voids within the bare earth digital terrain model. Digital image data using a calibrated digital frame camera will also be gathered. The LiDAR data is proprietary. However, copies of the digital camera footage will be made available to Hunters and Trappers Committees and Renewable Resource Councils, upon request. Maps using the LiDAR data will likely go on the public record of various regulatory agencies involved in permitting any construction activities that use such data. The survey will be carried out from September 12-30, 2006. The UTM NAD 83 8 North coordinates for the ground stations are: 1) 7704016 578379; 2) 7688140 569972; 3) 7653324 558742; 4) 7654318 556706; 5) 7647174 563896; 6) 7671452 530578; 7)7659502537065E; 8) 7679553 561157; 9)7664276 557910.