UAV Imagery and Topographic Data from Black Hollow 10 September 2025, upper Cache la Poudre River

This dataset contains a point cloud, digital elevation model (DEM), orthoimagery, and uncrewed aerial vehicle (UAV) imagery covering 0.1 km2 of the Black Hollow drainage located along the upper Cache la Poudre River, in Larimer County, Colorado, USA. These products show erosional and depositional features, most notably wood jams (accumulation of large woody debris in a channel), resulting from a debris-flow event that occurred on  July 20, 2021 (Rengers and others, 2026). A focused higher resolution point cloud, DEM, and orthoimagery of one large wood jam feature is included as well.

UAV imagery was collected during three uncrewed aerial system (UAS) flights on September 10, 2025 using a United States Geological Survey (USGS) -approved Skydio X10 platform, including two on-nadir mapping flights and one three-dimensional capture flight focused on a large logjam feature. A total of 870 georeferenced images were processed using structure-from-motion (SfM) photogrammetry techniques implemented in Agisoft Metashape (v. 2.1.3) to generate the point cloud and derived products. Due to site access limitations, no local ground control points were used, and initial georeferencing relied on onboard Global Navigation Satellite System (GNSS) positioning.

To improve spatial consistency with existing topographic data, the SfM-derived point clouds were vertically and horizontally aligned to the most recent U.S. Geological Survey (USGS) 3D Elevation Program (3DEP) lidar point cloud (1-meter resolution) using an iterative closest point (ICP) registration approach constrained to stable terrain surfaces (e.g. unvegetated hillslopes outside of the channel) (RMS error = 1.178 m). The two point clouds and DEMs derived from them are projected in North America Datum (NAD) 1983 (2011) UTM Zone 13N with elevations referenced to NAVD 88. The two orthomosaics, produced from the SFM-derived point cloud prior to ICP registration, are projected in North America Datum (NAD) 1983 (2011) UTM Zone 13N. The resulting products provide high-resolution topographic and imagery data that may be used for visualization and comparison with other spatial datasets, with consideration of the limitations associated with the absence of ground control.

Disclaimer: Any use of trade, firm, or product names is for descriptive purposes only and does not imply endorsement by the U.S. Government.
 
References:

Rengers, F.K., Stoker, J.M., Kostelnik, J., Kean, J.W., Wohl, E.E., Barnhart, K.R. et al., 2026, Channel morphology and large wood control postfire debris-flow erosion and deposition: Earth Surface Processes and Landforms, v. 51, no. 4, article e70287, https://doi.org/10.1002/esp.70287.
 
U.S. Geological Survey, 2025, CO_ArapahoRooseveltPikeNF_1_D23, in 3D Elevation Program lidar point cloud: The National Map, accessed December 19, 2025, at https://prd-tnm.s3.amazonaws.com/StagedProducts/Elevation/metadata/CO_A….