Calculating the Uncertainty of a Structure from Motion (SfM) Model, Cadman Quarry, Monroe, Washington

Structure from Motion (SfM) is a new form of photogrammetry that automates the rendering of georeferenced 3D models of objects using digital photographs and independently surveyed Ground Control Points (GCPs). This project seeks to quantify the error found in Digital Elevation Models (DEMs) produced using SfM. I modeled a rockslide found at the Cadman Quarry (Monroe, Washington) because the surface is vegetation-free, which is ideal for SfM and Terrestrial LiDAR Scanner (TLS) surveys. By using SfM, TLS, and GPS positioning at the same time, I attempted to find the deviation in the SfM model from the TLS model and GPS points. Using the deviation, I found the Root-Mean-Square Error (RMSE) between the SfM DEM and GPS positions. The RMSE of the SfM model when compared to surveyed GPS points is 17cm. I propagated the uncertainty of the GPS points with the RMSE of the SfM model to find the uncertainty of the SfM model compared to the NAD 1984 datum. The uncertainty of the SfM model compared to the NAD 1984 is 27cm. This study did not produce a model from the TLS that had sufficient resolution on horizontal surfaces to compare to surveyed GPS points.

Quantifying ice-shelf basal melt and ice-stream dynamics using high-resolution DEM and GPS time series

Thesis (Ph.D.)--University of Washington, 2016-06

The role of large woody debris and riparian forest in channel avulsion in the Carbon River, Mount Rainier National Park, Washington

A specific type of natural log jam in the upper alluvial reach of the Carbon River was found to influence secondary channel avulsion, causing flooding hazards to the adjacent Carbon River Road in the northwest quadrant of Mount Rainier National Park, Washington. The fence-like natural log jam was characterized by large woody debris buttressed horizontally against standing riparian trees (i.e. ìfence railsî and ìfence postî). The objectives of this report are two-fold. First, physical characteristics and spatial distribution were documented to determine the geomorphic controls on the fence-like log jams. Second, the function and timing of the natural log jam in relation to channel avulsion was determined to provide insight into flooding hazards along the Carbon River Road. The fence-like log jams are most abundant in the upper reaches of the Carbon River between 3.0 and 5.5 kilometers from the Carbon Glacier terminus, where longitudinal gradient significantly decreases from about 0.06 to 0.03. Sediment impoundment can occur directly upstream of the fence-like log jam, creating vertical bed elevation difference as high as 1.32 meters, and can form during low magnitude, high frequency flood event (3.5-year recurrence interval). In some locations, headcuts and widening of secondary channel were observed directly to the side of the log jams, suggesting its role in facilitating secondary channel avulsions. Areas along the Carbon River Road more prone to damages from avulsion hazards were identified by coupling locations of the log jams and Relative Water Surface Elevation map created using the 1-meter 2012 Light Detection and Ranging Digital Elevation Map. Ultimately, the results of this report may provide insight to flooding hazards along the Carbon River Road from log jam-facilitated channel avulsion.