High-resolution orthoimagery and digital surface model of Foster Lake, Oregon, December 2023

In cooperation with the U.S. Army Corps of Engineers (USACE), the U.S. Geological Survey (USGS) surveyed ground control points and coordinated aerial photograph acquisition of Foster Lake, located near Sweet Home and Foster, Oregon. Foster Lake is a multi-purpose reservoir impounded by the 38.4-meter ([m]; 126-foot [ft]) tall Foster Dam along the South Santiam River. Aerial photographs were acquired by the Civil Air Patrol (CAP) December 16, 2023, when water levels were at an elevation of 188 m (616 ft; National Geodetic Vertical Datum of 1929 [NGVD29]), near typical annual “low pool” or minimum-conservation pool for flood-risk management operations (187 m [613 ft]). Photographs were acquired at a single altitude with a WaldoAir XCAM Ultra 50 camera mounted on a Cessna aircraft and captured the entire reservoir area as defined by full pool (or maximum-conservation pool, 194 m [637 ft]), including the major rivers entering the reservoir, the South and Middle Santiam Rivers, as well as other smaller tributaries. The USGS applied structure-from-motion (SfM) techniques to these aerial photographs, following the workflow outlined in Over and others (2021) and used for similar datasets (Schwid and others, 2025) to generate a three-dimensional xyz point cloud, digital surface model (DSM), and orthomosaic of Foster Lake. 

This documentation describes the aerial photographs acquired by the Civil Air Patrol on December 16, 2023, a CSV file containing ground control point locations surveyed on November 5 and 6, 2024, that were used to spatially register SfM datasets, a high-resolution point cloud, DSM, and orthomosaic generated from SfM techniques using the aerial photographs, and a polygon shapefile including the footprint (spatial coverage) of the DSM and orthomosaic. 

References:
Over, J.R., Ritchie, A.C., Kranenburg, C.J., Brown, J.A., Buscombe, D., Noble, T., Sherwood, C.R., Warrick, J.A., and Wernette, P.A., 2021, Processing coastal imagery with Agisoft Metashape Professional Edition, version 1.6—Structure from motion workflow documentation: U.S. Geological Survey Open-File Report 2021–1039, 46 p., accessed March 11, 2026, at https://doi.org/10.3133/ofr20211039.

Schwid, M.F., Keith, M.K., and Overstreet, B.T., 2025, High-resolution orthoimagery and digital surface models of Fern Ridge Lake, Oregon, during annual low pool, January and February, 2023: U.S. Geological Survey data release, accessed March 11, 2026, at https://doi.org/10.5066/P1Q5K657.