Point cloud, digital surface model (DSM), and orthoimagery derived from historical aerial imagery of the South Cow Mountain Recreational Area, Lake County, California, May 27, 1977
Dates
Publication Date
2023-03-13
Time Period
1977-05-27
Citation
Bond, S., and Curtis, J.A., 2023, Point cloud, digital surface model (DSM), and orthoimagery derived from historical aerial imagery of the South Cow Mountain Recreational Area, Lake County, California, May 27,1977: U.S. Geological Survey data release, https://doi.org/10.5066/P9Q0JGWI.
Summary
The USGS, in cooperation with the U.S. Bureau of Land Management (BLM), created a series of geospatial products of the South Cow Mountain Recreational Area, Lake County, California, using historic aerial imagery and structure-from-motion (SfM) photogrammetry methods. Products were generated from stereo historical aerial imagery acquired by the BLM in May of 1977. The aerial imagery were downloaded from the USGS Earth Resources Observation and Science (EROS) Data Center's USGS Single Aerial Frame Photo archive and a was created using USGS guidelines. Data were processed using SfM photogrammetry to generate a three-dimensional point cloud (.laz) that identifies pixels of an object from multiple images taken from various angles and calculates [...]
Summary
The USGS, in cooperation with the U.S. Bureau of Land Management (BLM), created a series of geospatial products of the South Cow Mountain Recreational Area, Lake County, California, using historic aerial imagery and structure-from-motion (SfM) photogrammetry methods. Products were generated from stereo historical aerial imagery acquired by the BLM in May of 1977. The aerial imagery were downloaded from the USGS Earth Resources Observation and Science (EROS) Data Center's USGS Single Aerial Frame Photo archive and a was created using USGS guidelines. Data were processed using SfM photogrammetry to generate a three-dimensional point cloud (.laz) that identifies pixels of an object from multiple images taken from various angles and calculates the x, y, and z coordinates of that object/pixel. The point cloud was processed to create a DSM (.tif) representing the continuous surface of the uppermost reflective surface (57.3 cm resolution). Finally, source images were stitched together based on shared pixels and orthogonally adjusted to the DSM to create a high resolution (approximately 18.3 cm) orthoimage (.tif) for the study area. This dataset includes a point cloud, digital surface model (DSM), and orthoimagery, as well as synthetic ground-control points (GCPs) and point clusters used to georeference the datasets. Separate metadata for each product are provided on the ScienceBase page for each child item.
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South_Cow_Mountain_CA_Point_Cloud_DSM_Orthoimagery_19770527.xml Original FGDC Metadata
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Purpose
These points provide the calculated XYZ (horizontal and vertical) coordinates and RGB (red-green-blue) values of the land surface on May 27, 1977. The product was created to demonstrate the use of structure-from-motion photogrammetry from historical aerial imagery for an erosion study and can be used to develop further datasets, such as digital elevation models, vegetation mapping, and land cover classification. However, due to the lack of high-quality GPS reference point, any direct volumetric comparison using these datasets by differencing the 1977 dense point cloud or Digital Surface Model (DSM) with more recent bare earth digital elevation models, should consider the horizontal and vertical Root-Mean-Square Error (RMSE), minimum thresholds of significance, as well as vegetation bias.
