Determining accurate elevations is important for many engineering and scientific applications, and finding these heights via GNSS increases efficiency and significantly reduces the costs as compared to precise geodetic leveling. The National Geodetic Survey (NGS) has published guidelines for determining both ellipsoidal and orthometric heights with GPS to within 2...
Small unmanned aircraft systems (UAS) carrying consumer-grade nonmetric cameras are increasingly utilized to generate high-resolution 3D geospatial data. Low cost, ease of operation, widespread availability and low altitude maneuvering capabilities of UAS, as well as the rapid development of technology and methods, make UAS-based photogrammetry applicable to many civil engineering...
Ground failures, in particular landsliding, liquefaction and lateral spreading can be triggered by seismic sources. The frequency, magnitude, and impact of these ground failures are highly dependent on the topography and geology of the site including its slope, depositional environment, and geotechnical properties as well as the proximity of the...
To derive ellipsoid heights on passive marks with cm-level accuracy, many current specifications require the collection and adjustment of long-duration, static Global Navigation Satellite System (GNSS) sessions. To increase efficiency, a survey procedure that includes real-time kinematic vectors from a real-time GNSS network (RTN) was evaluated. Thirty different “hybrid” networks...
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Daniel T. Gillins
To derive ellipsoid heights on passive marks with cm-level accuracy, many
Lateral spread is a pervasive type of liquefaction-induced ground failure that occurs on gentle slopes or near free-faces, such as river channels. Resulting horizontal displacements can reach up to several meters, and can be considerably damaging to foundations, bridges, roadways, pipelines, etc. In the 1990s, Bartlett and Youd (1992a, 1995)...