Tripod LiDAR Deformation Monitoring: Experiments and Examples Abstract

abstract

  • We explore the capability of Tripod LiDAR (T-LiDAR) for deformation monitoring applications with controlled experiments and field examples from Oahu, Hawai`i. We use an Optech ILRIS 3-D near-infrared (1.2 micron wavelength) system. The manufacturer's specifications state a 7-8 mm range resolution at a distance of 100m, but this has not been verified by the science community nor has the system been systematically tested at a variety of ranges. We built a stable table with a grid of peg holes at known distances to measure offsets of a geodetic target (a Leica GPS antenna and radome). We scanned the radome from variable distances and with variable spot spacing and used the 3D point cloud data to model the phase center of the radome by fitting all data points to a spherical model in a local co-ordinate frame. Preliminary results show that from over 1400 individual scans with spot-spacing ranging from 2 mm to 20 mm and over distances of more than 500 meters, the phase center of the radome derived from T-LiDAR measurements and solid modeling is achieved with better than 2-4 mm standard deviation. Similarly, we offset the radome from 1cm-1m and found that known offsets were reproduced with better than ~1-1.5 cm repeatability at the 2 sigma level. We also found that T-LiDAR measured offset resolution degrades slightly with increasing distance from the target.

authors

publication date

  • 2008

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