Ground control point locations associated with images collected during unmanned aerial systems (UAS) flights over Coast Guard Beach, Nauset Spit, Nauset Inlet, and Nauset Marsh, Cape Cod National Seashore, Eastham, Massachusetts on 1 March 2016 (Text file and photos)

Thirty-two ground control points are listed in the file CACO_ground_control_points_20160301.txt. Most (28) were targets placed by the USGS field crew but four were man-made features already in place. Of these, one target (B1) was removed and two targets (P6 and T2) were moved between flight 1 and flight 2 in advance of the rising tide. The labels associated with locations of moved targets are appended with _MOVED. Two additional locations without targets (designated fake1 and fake2) were used to improve photogrammetric results in the western marsh portion of the survey area. Placed targets included commercial targets (4 ft x 4 ft x 4-mil thick PVC plastic sheets with black and white diamond patterns and grommets in corners; Berntsen International, Inc. product number AT48IC-STK), plywood targets (2 ft x 2 ft x 1/2-inch thick plywood boards painted with black and white squares), and black plastic trash bags. The commercial targets were designated Tnn and the plywood targets were designated Pnn, where nn is the target number. The trash bags were designated Bxx or BNxx, where xx is the order in which they were deployed. In-place features included BE, BW, FLAGSTONE, and MAN-SW. Photos of these features are included so that they can be identified in the aerial images. Also included are images showing the location of the two points without targets (fake1 and fake2). Horizontal coordinates for these points were picked from a preliminary version of an orthophoto; vertical coordinates were determined from LiDAR data in the 2013-2014 U.S. Geological Survey CMGP LiDAR: Post Sandy (MA, NH, RI) https://coast.noaa.gov/dataviewer/index.html?action=advsearch&qType=in&qFld=ID&qVal=4914. Two differential GPS (Global Positioning System) rover instruments were used by field crews to map targets for ground control points. One was a Spectra Precision model SP80 GNSS (Global Navigation Satellite System) receiver linked via Bluetooth to a data collector (Carlson CHC LT30 Handheld Terminal running Carlson SurvCE v. 4.06 software under Windows Mobile v. 6.1 Professional operating system). This instrument was operated by Sandy Brosnahan. The second rover was a Spectra Precision model ProMark 800 GNSS receiver linked to a similar data collector, operated by Barry Irwin. Both rover antennas were mounted on 2-m survey rods with bubble levels and 5-cm (2-inch) sand feet. The rovers received differential GPS corrections in real time from a base station (described below). The rovers were used to map three reference points established near the base station at the beginning and end of the day. The average absolute deviation largest vertical difference measured was +0.03 m. A differential GPS base station was established over a temporary benchmark on the lawn of the NEED building at Coast Guard Beach. The base station was a Spectra model SP80 GNSS receiver with UHF radio and external antenna mounted on a separate tripod. The antenna height was 2.25 m. The coordinates of the reference point (named CGB_OPUS) were determined from an ultra-rapid precise orbit On-line Positioning User Service (OPUS) solution based on GPS data from a five-hour occupation on January 11, 2016. Coordinates in NAD83 2010(2011) UTM Zone 19 North, elevation NAVD88 (geoid 12a) for the reference point are: Northing (m) 4632792.698 (+/-0.002), Easting (m) 421296.521 (+/-0.003), Orthometric elevation (m) 12.880 (+/-0.012). The uncertainties in parentheses represent peak-to-peak values. Ground control point measurements were converted to NAD83 2010(2011), UTM Zone 19 North (meters) NAVD88 (Geoid 12a) as the data were collected. The measurements were exported from the data collector in a text file that was edited to isolate the ground control points and remove extraneous columns (CACO_ground_control_points_20160301.txt).

Added keywords section with USGS persistent identifier as theme keyword.