Braddock East camera locations and attitudes for low-altitude aerial images collected during unmanned aerial systems (UAS) flights over of the Lake Ontario shoreline in the vicinity of Braddock Bay, New York in July 2017

During USGS field activity 2017-042-FA, digital images were taken approximately 80 and 100 m above the ground on July 10 - 14, 2017, with a Ricoh GRII digital camera mounted in a 3DR Solo quadcopter operated by the U.S. Geological Survey. This camera location file, for the Braddock Bay project, was created using a standard processing flow as described in the processing steps below. These camera locations are the product of one of several photogrammetry projects from field activity 2017-042-FA. Two projects incorporated flights over Braddock Bay on July 10 and 11, 2017 (Braddock West, Braddock East); four were used for flights in the vicinity of Sodus Bay on July 12, 13, and 14, 2017 (Lake Bluff / Crescent Bar, Crescent Bar / Charles Point, Sodus North, and Greig Street); and one project incorporated flights over Chimney Bluffs on July 14, 2017.
For this camera location file, original camera position estimates were determined using Mission Planner software (version 1.3.49). These position estimates are written to the header of JPEG images in a process know as geotagging. Geotagging functionality in Mission Planner is accessed from the main menu by clicking 'control' and 'F', and then choosing 'GeoRef Images' from the menu that pops up. Geotagging requires a telemetry log (created by mission planner during survey flight), photos (collected by the Ricoh camera during flight), and a time offset between camera and GPS if applicable. The updated camera locations also present in this dataset were determined using photogrammetry software (Agisoft Photoscan Professional v. 1.3.2), and differ from the original position estimates due to photogrammetric correction and ground control adjustments.

The following steps make up the general processing flow for creating digital elevation models from UAS flights:1. Geotagged images (see source citation) containing useful imagery from the survey area were imported into Agisoft Photoscan Professional v. 1.3.2 software using the “Add photos…” tool. Photos taken before and immediately after takeoff, photos taken immediately prior to and after landing, and photos with 100% water were not loaded into the project. Project coordinate system is set to EPSG::7660 WGS84 (G1150) geocentric coordinate system.2. Using ”Convert”, the coordinate system of the images (called “cameras” in Photoscan) was converted from native latitude/longitude WGS84 (G1150) coordinate system to meters in NAD83/UTM zone 18N (EPSG::26918).3. The photos were processed through an initial alignment and optimization procedure using the following settings:Alignment - Accuracy: “High”; Pair selection: “Reference”; Key point limit: 80,000; Tie point limit; 0 (unlimited). Adaptive camera model fitting option was selected.Optimization - Lens-calibration parameters f, cx, cy, k1, k2, k3, p1, and p2 were included; b1, b2, and higher-order parameters k4, p3, and p4 were not.4. The sparse point cloud (also known as tie points; created as a result of photo alignment and optimization) was edited using an iterative error-reduction procedure to filter the data. This was done in several iterations of a process called "Gradual Selection" to first to reduce reconstruction uncertainty (to a unitless value of 10) and then projection accuracy (to a weighted value of 3).5. Ground control points were created by first letting the software automatically detect markers where it finds all of the 4-ft square black/white targets deployed (false targets that are sometimes detected were manually deleted). The automatically-generated marker labels were manually changed to match the names in the survey notes and GCP location files.6. "Import markers” was used to load the GCP location file, which assigned coordinates (northing, easting, and elevation in UTM Zone 18 North meters in NAD83 and NAVD88 coordinate systems) from the location file to the detected markers. The locations of auto-detected markers were retained.7. Another round of "Gradual Selection" was done to reduce the reprojection error (to a value of 0.3 pixels, unless more than 10% of the points would be removed).8. A dense point cloud was then created with the parameters "High" quality and “Aggressive” depth filtering.9. A DEM was create with the parameters Source data="Dense Cloud" Interpolation="Enabled" Resolution="0.1"10. An orthomosaic was create with the parameters Surface="DEM" Blending mode="Mosaic" Pixel size X="0.05" Pixel size Y="0.05"11. The camera locations data (this dataset) was exported in CSV text format (2017-07-10_Braddock_East_CAMERAS.csv) from Photoscan with the following parameters (Items=Cameras, Delimiter=Comma, Columns=[all boxes checked on] with Precision=6). This file was manually edited to remove columns that contained no data for all records and to fill those columns for the photos not successfully aligned with a no-data value of "NaN". Then the file renamed to 2017042FA_BraddockEast_CameraLocations.csv).

Added keywords section with USGS persistent identifier as theme keyword.