Jenna A. Brown Stephen T. Bosse Christine J. Kranenburg 20230821 tabular and raster digital data Jenna A. Brown Stephen T. Bosse Christine J. Kranenburg 20230630 data release doi:10.5066/P9K23VGX Dover, DE U.S. Geological Survey https://doi.org/10.5066/P9K23VGX https://www.sciencebase.gov/catalog/item/647e2e47d34eac007b55e39d The U.S. Geological Survey (USGS) surveyed 7 features visible from the air to be used as ground control points (GCP) along the Delaware Atlantic coast as well as 2 reference bench marks. Global Positioning System (GPS) data were collected on July 7, 2021 in support of aerial imagery surveys documenting current topographic conditions along the coast and will be used as control and check points in Structure-from-Motion (SfM) photogrammetry processing to produce topographic maps. This dataset consists of horizontal and vertical positions of permanent GCPs, measured using Real-Time Kinematic (RTK) Global Navigation Satellite System (GNSS) equipment. The data are provided in comma-separated values (.csv) delimited text format, in projected (Universal Transverse Mercator Zone 18N) coordinates, and vertical measurements are provided as orthometric heights. Horizontal coordinates are referenced to the North American Datum of 1983 (NAD83(2011)), and orthometric heights are referenced to the North American Vertical Datum of 1988 (NAVD88), GEOID12B. Additional information as well as photographs for each GCP are also included. The purpose of this dataset is to provide geospatial GCP data in support of aerial imagery surveys along the Delaware Atlantic coast; these data can be used as control and check points in SfM processing to create and validate orthomosaic images, point clouds, and digital elevation models (DEMs). 20210707 ground condition Complete None planned -75.15868933 -75.05338639 38.78692229 38.45125245 ISO 19115 Topic Category geoscientificInformation imageryBaseMapsEarthCover oceans None U.S. Geological Survey USGS Coastal and Marine Hazards and Resources Program CMHRP USGS Thesaurus GPS measurement geospatial datasets topography geomorphology USGS Metadata Identifier USGS:647e2e47d34eac007b55e39d Geographic Names Information Service (GNIS) Delaware Cape Henlopen None Cape Henlopen State Park Delaware Seashore State Park None USGS-authored or produced data and information are in the public domain from the U.S. Government and are freely redistributable with proper metadata and source attribution. Please recognize and acknowledge the U.S. Geological Survey as the originator of the dataset and in products derived from these data. Jenna A. Brown U.S. Geological Survey, MD-DE-DC Water Science Center mailing and physical

1289 McD Dr

Dover DE 19901 USA (443)-498-5500 jennabrown@usgs.gov https://www.sciencebase.gov/catalog/file/get/647e2e47d34eac007b55e39d?f=__disk__1c%2F8b%2F0d%2F1c8b0d44f67a8353c04f24b73be76c275ec55e26&allowOpen=true Regional map showing the GCP and bench mark locations along the Delaware Atlantic coast, measured on July 7, 2021. JPEG Data collection was funded by the U.S. Geological Survey. The accuracy of the GPS data was determined based on the measurement of two established benchmarks in the area; see the Notes attribute in the data file to identify the GCPs corresponding to benchmarks. This dataset is derived from a single field survey using identical equipment, set-ups, and staff; therefore, the dataset is internally consistent. This dataset is considered complete for the information presented, as described in the abstract. Users are advised to read the rest of the metadata record carefully for additional details. The horizontal accuracy of the GPS data is on the order of 6.6 cm, determined as the maximum difference between the reported horizontal position for two established benchmarks in the area and the corresponding RTK measurements. The vertical accuracy of the data is on the order of 1.2 cm, determined as the maximum difference between the reported vertical position for two established benchmarks in the area and the corresponding RTK measurements. PLANNING & DATA ACQUISITION Optimal survey locations were pre-planned using available aerial imagery, with the following criteria for selecting a GCP: easily identified in aerial images, permanent and stationary feature, surrounded by open sky, and with limited relief from the surrounding surface. The GPS data were collected with a single Trimble R10 GNSS receiver, mounted on a 2-meter survey pole attached to a bipod, connected to the GNSS Continuously Operating Reference Stations (CORS) network, NCBX site in Buxton, North Carolina. At each GCP location, RTK corrections were sampled at 1-second intervals for 180 seconds and the average position was recorded in projected coordinates (UTM Zone 18N, referenced to NAD83 (2011)) and orthometric height (referenced to NAVD88 using GEOID12B); the GNSS antenna height was accounted for during data collection and export. Additionally, reference photographs of each GCP were taken during the survey to aid in identifying the GCPs in aerial imagery. 20210707 Jenna A. Brown U.S. Geological Survey, MD-DE-DC Water Science Center mailing and physical

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Dover DE 19901 USA (443)-498-5500 jennabrown@usgs.gov @usgs.gov DATA PUBLICATION The data were prepared for publication by saving the horizontal and vertical position data for each GCP in a single file (2021-0707_DE_AtlanticCoast_GCPs.csv). Notes describing the measured GCP features were included in the .csv to aid in identifying the GCPs in aerial imagery. Surveyed points that were re-measured (due to instrument setup error) or used for instrument testing were not included in the data release. Reference photographs for each GCP were saved in a directory labeled GCP_photographs, to also aid in identifying the GCPs in aerial imagery. Metadata was written to all photograph headers using a script and batch processing to execute ExifTool (https://exiftool.org/) and populate fields with information for each GCP from the .csv file. To extract the information from the image headers using ExifTool, the following command can be used (tested with ExifTool version 12.62): exiftool -csv -f -filename -GPSDateStamp -GPSTimeStamp -GPSLongitude -GPSLatitude -n -Artist -Credit -comment -keywords -Caption -Copyright -CopyrightNotice -Caption-Abstract -ImageDescription *.jpg > out.csv The -csv flag writes the information out in a comma-delimited format. The -n option formats the latitude and longitude as signed decimal degrees. 20230530 Jenna A. Brown U.S. Geological Survey, MD-DE-DC Water Science Center mailing and physical

1289 McD Dr

Dover DE 19901 USA (443)-498-5500 jennabrown@usgs.gov Point Point 9 Universal Transverse Mercator 18 0.9996 -75.0 0.0 500000.0 0.0 coordinate pair 0.001 0.001 meters North American Datum of 1983 (2011) GRS 1980 6378137.0 298.257223563 North American Vertical Datum of 1988 0.001 meters Explicit elevation coordinate included with horizontal coordinates 2021-0707_DE_AtlanticCoast_GCPs.csv Comma-delimited text file containing position, elevation, and other information related to GCPs surveyed along the Delaware Atlantic coast on July 7, 2021. U.S. Geological Survey GCP Identifier Identifier associated with each individual GCP, numbered consecutively from south to north; points labeled BM represent established benchmarks. U.S. Geological Survey GCP Identifiers range between GCP1 and GCP7, with two benchmarks (BM1 and BM2). Local Date Local date of data collection in MM/DD/YYYY format. U.S. Geological Survey 07/07/2021 07/07/2021 N/A Easting (NAD83, UTM 18N, m) NAD83(2011) UTM x-axis coordinate (Zone 18N) U.S. Geological Survey 486217.690 495341.684 Meters Northing (NAD83, UTM 18N, m) NAD83(2011) UTM y-axis coordinate (Zone 18N) U.S. Geological Survey 4255885.695 4293143.509 Meters Latitude (NAD83) NAD83(2011) U.S. Geological Survey 38.45125176 38.78699545 Decimal degrees Longitude (NAD83) NAD83(2011) U.S. Geological Survey -75.15866122 -75.05338783 Meters Orthometric Height (NAVD88, m) NAVD88 (GEOID12B) orthometric height U.S. Geological Survey 1.018 3.204 Meters Notes Notes describing the features and location of each GCP. U.S. Geological Survey N/A U.S. Geological Survey GS ScienceBase mailing address

Denver Federal Center, Building 810, Mail Stop 302

Denver CO 80225 United States 1-888-275-8747 sciencebase@usgs.gov The GCP locations, elevations, and other notable information are available in .csv format, and associated reference photographs (GCP_photographs.zip) of each GCP are available in .jpg format. This publication was prepared by an agency of the United States Government. Although these data were processed successfully on a computer system at the U.S. Geological Survey, no warranty expressed or implied is made regarding the display or utility of the data on any other system, nor shall the act of distribution imply any such warranty. The U.S. Geological Survey shall not be held liable for improper or incorrect use of the data described and (or) contained herein. Reference herein to any specific commercial product, process, or service by trade name, trademark, manufacturer, or otherwise does not constitute or imply its endorsement, recommendation, or favoring by the United States Government or any agency thereof. ASCII The ASCII (.csv) file can be opened with any text editor. https://www.sciencebase.gov/catalog/item/647e2e47d34eac007b55e39d Ground control point data, available in CSV format, can be downloaded from the data table on the data release landing page, which is accessed via the Network_Resource_Name link. None. 20260306 Jenna A. Brown U.S. Geological Survey, MD-DE-DC Water Science Center mailing and physical

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Dover DE 19901 USA (443)-498-5500 jennabrown@usgs.gov Content Standard for Digital Geospatial Metadata FGDC-STD-001-1998