Digital Surface Model representing Head of the Meadow Beach, Truro, MA on March 10, 2023

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Frequently anticipated questions:

What does this data set describe?

Title:
Digital Surface Model representing Head of the Meadow Beach, Truro, MA on March 10, 2023
Abstract:
The data in this release re-map the beach and nearshore environment at Head of the Meadow Beach in Truro, MA and provide updated environmental context for the 2020 CoastCam installation that looks out at the coast shared by beachgoers, shorebirds, seals, and sharks. This is related to the field activity 2022-015-FA and a collaboration with the National Park Service at Cape Cod National Seashore to monitor the region that falls within the field of view of CoastCam CACO-01, which are two video cameras aimed at the beach. In March and April 2023, U.S. Geological Survey and Woods Hole Oceanographic Institute (WHOI) scientists conducted field surveys to collect topographic and bathymetric data. Images of the beach for use in structure-from-motion were taken with a camera (SONY a6000) and a post-processed kinematic (PPK) system attached to a helium powered balloon-kite (Helikite). High-precision GPS targets (AeroPoints) and numbered black and white tarps were used as ground control points. Bathymetry was collected in the nearshore using a single-beam echosounder mounted on a surf capable self-righting electric autonomous surface vehicle. Agisoft Metashape (v. 1.8.1) was used to create a digital surface model and orthomosaic with the collected imagery.
Supplemental_Information:
For more information about the WHCMSC Field Activity, see https://cmgds.marine.usgs.gov/fan_info.php?fan=2023-011-FA.
  1. How might this data set be cited?
    Over, Jin-Si R., 20230725, Digital Surface Model representing Head of the Meadow Beach, Truro, MA on March 10, 2023: data release DOI:10.5066/P9FYVLCD, U.S. Geological Survey, Coastal and Marine Hazards and Resources Program, Woods Hole Coastal and Marine Science Center, Woods Hole, MA.

    Online Links:

    This is part of the following larger work.

    Over, Jin-Si R., Sherwood, Chris R., and Traykovski, Peter A., 2023, Topographic and bathymetric data, structure from motion imagery, and ground control data collected at Head of the Meadow Beach, Truro, Massachusetts in March and April 2023, U.S. Geological Survey Field Activity 2023-011-FA.: data release DOI:10.5066/P9FYVLCD, U.S. Geological Survey, Reston, VA.

    Online Links:

    Other_Citation_Details:
    Suggested citation: Over, J.R., Sherwood, C.R., and Traykovski, P.A., 2023, Topographic and bathymetric data, structure from motion imagery, and ground control data collected at Head of the Meadow Beach, Truro, Massachusetts in March and April 2023, U.S. Geological Survey Field Activity 2023-011-FA: U.S. Geological Survey data release, https://doi.org/10.5066/P9FYVLCD.
  2. What geographic area does the data set cover?
    West_Bounding_Coordinate: -70.07969463
    East_Bounding_Coordinate: -70.07499809
    North_Bounding_Coordinate: 42.05246002
    South_Bounding_Coordinate: 42.04958206
  3. What does it look like?
    https://www.sciencebase.gov/catalog/file/get/646515aed34ec179a83dc2de?name=2023-011-FA_Truro_DSM_browse.JPG&allowOpen=true (JPEG)
    Elevation relative to NAVD88-colored image of topography
  4. Does the data set describe conditions during a particular time period?
    Calendar_Date: 10-Mar-2023
    Currentness_Reference:
    ground condition; one day of data collection on March 10, 2023
  5. What is the general form of this data set?
    Geospatial_Data_Presentation_Form: raster
  6. How does the data set represent geographic features?
    1. How are geographic features stored in the data set?
      This is a Raster data set. It contains the following raster data types:
      • Dimensions 1260 x 1540, type Pixel
    2. What coordinate system is used to represent geographic features?
      Grid_Coordinate_System_Name: Universal Transverse Mercator
      Universal_Transverse_Mercator:
      UTM_Zone_Number: 19
      Transverse_Mercator:
      Scale_Factor_at_Central_Meridian: 0.999600
      Longitude_of_Central_Meridian: -69.000000
      Latitude_of_Projection_Origin: 0.000000
      False_Easting: 500000.000000
      False_Northing: 0.000000
      Planar coordinates are encoded using row and column
      Abscissae (x-coordinates) are specified to the nearest 0.001
      Ordinates (y-coordinates) are specified to the nearest 0.001
      Planar coordinates are specified in meters
      The horizontal datum used is North American Datum of 1983 (National Spatial Reference System 2011).
      The ellipsoid used is GRS_1980.
      The semi-major axis of the ellipsoid used is 6378137.0.
      The flattening of the ellipsoid used is 1/298.257222101.
      Vertical_Coordinate_System_Definition:
      Altitude_System_Definition:
      Altitude_Datum_Name: North American Vertical Datum of 1988
      Altitude_Resolution: 0.001
      Altitude_Distance_Units: meters
      Altitude_Encoding_Method:
      Explicit elevation coordinate included with horizontal coordinates
  7. How does the data set describe geographic features?
    2023-011-FA_Truro_DSM_UTM19N_NAVD88_25cm.tif
    A raster dataset with encoded elevation values of Head of the Meadow Beach in Truro, MA on March 10, 2023. Pixel resolution is 25 cm. (Source: USGS)
    Value
    Surface elevation orthometric height NAVD88 (m) using Geoid 2018 in NAD83(2011) UTM Zone 19N (Source: producer defined)
    ValueDefinition
    -999No data
    Range of values
    Minimum:2.788
    Maximum:28.597
    Units:meters
    Entity_and_Attribute_Overview:
    Pixels represent elevation in meters relative to North American Vertical Datum of 1988 (NAVD88). The filename is formatted as "2023-011-FA_Truro_DSM_UTM19N_NAVD88_25cm.tif", where 2023-011 is the USGS Field activity ID, location is Truro, where Head of the Meadow Beach is, DSM is Digital Surface Model, UTM19N_NAVD88 is the coordinate reference system, and 25cm indicates the resolution of the grid.
    Entity_and_Attribute_Detail_Citation: USGS Field Activity 2023-011-FA

Who produced the data set?

  1. Who are the originators of the data set? (may include formal authors, digital compilers, and editors)
    • Jin-Si R. Over
  2. Who also contributed to the data set?
  3. To whom should users address questions about the data?
    Jin-Si R. Over
    U.S. Geological Survey, Woods Hole Coastal and Marine Science Center
    Geographer
    384 Woods Hole Rd.
    Woods Hole, MA

    508-548-8700 x2297 (voice)
    jover@usgs.gov

Why was the data set created?

These data may be used as a high-resolution elevation dataset of Head of the Meadow Beach to observe conditions and change over time and to validate the CoastCam.

How was the data set created?

  1. From what previous works were the data drawn?
  2. How were the data generated, processed, and modified?
    Date: Apr-2023 (process 1 of 1)
    DSM was created in Agisoft Metashape v. 1.8.1 using the following general steps (see Over and others, 2021):
    1. Project was created with imagery (located in larger work citation 2023011FA_Truro_f1.zip) and position (located in larger work citation 2023011FA_Truro_f1_photolocations.csv) data brought in using the NAD83(2011)/UTM19N and NAVD88 datums. A 0.15 m GNSS/IPS offset in the z direction was used to represent the approximate offset of the GNSS mount and camera on the Helikite. Photos were aligned at a low accuracy and then GCPs were automatically detected in the point cloud. Ten GCPs (2023011FA_Truro_nav_GCPs.csv) were located.
    2. GCP horizontal and vertical accuracy was set 0.02/0.05 m and accuracies for the camera positions were set to 0.10 m. The photos were re-aligned with high accuracy (the pixels are not subsampled for increased processing speed) using a keypoint limit of 40,000 and unlimited tie points.
    3. Metashape software refined and optimized, using least squares, the camera positions, GCPs, and lens model using gradual selection and optimization parameters of: Reprojection uncertainty = 15, Projection accuracy = 4, and Reprojection error = 0.3 to minimize the distance between the measured points and the software created points (see Over and others, (2021) for a detailed discussion on these parameters).
    4. A dense point cloud was generated using high-quality (images are not subsampled) and a low frequency filtering algorithm. The dense point cloud was then edited by hand to remove erroneous points before generating a digital surface model with no interpolation (the software refers to all models as "elevation models", but a surface model includes vegetation/canopy returns whereas a terrain model would be only bare earth returns).
    5. The digital surface model was then exported from the software at a resolution of 25 cm in NAD83(2011)/UTM Zone 19N and NAVD88 (m) Person who carried out this activity:
    Jin-Si R. Over
    U.S. Geological Survey, Woods Hole Coastal and Marine Science Center
    Geographer
    384 Woods Hole Rd
    Woods Hole, MA

    508-548-8700 x2297 (voice)
    jover@usgs.gov
  3. What similar or related data should the user be aware of?
    Over, Jin-Si R., Sherwood, Chris R., Traykovski, Peter A., and Marsjanik, Eric, 2022, Topographic and bathymetric data, structure from motion imagery, and ground control data collected at Head of the Meadow Beach, Truro, MA in March 2022, U.S. Geological Survey Field Activity 2022-015-FA: data release DOI:10.5066/P9GEVWG1, U.S. Geological Survey, Reston, VA.

    Online Links:

    Other_Citation_Details:
    This publication is the latest survey data of Head of the Meadow Beach from 2022.
    Over, Jin-Si R., Sherwood, Chris R., and Traykovski, Peter A., 2022, Topographic and bathymetric data, structure from motion imagery, and ground control data collected at Head of the Meadow, Truro in February 2021, U.S Geological Survey Field Activity 2021-014-FA: data release DOI:10.5066/P9D94NZ3, U.S. Geological Survey, Reston, VA.

    Online Links:

    Other_Citation_Details:
    This publication is the survey data of Head of the Meadow Beach from 2021.
    Over, Jin-Si R., Sherwood, Chris R., Traykovski, Peter A., Brosnahan, Sandra M., Marsjanik, Eric E., and Borden, John S., 2021, Topographic and bathymetric data, sediment samples, and beach imagery collected at Head of the Meadow, Truro in March 2020, U.S Geological Survey Field Activity 2020-015-FA: data release DOI:10.5066/P9KSG1RQ, U.S. Geological Survey, Reston, VA.

    Online Links:

    Other_Citation_Details:
    This publication is the survey data of Head of the Meadow Beach from 2020.

How reliable are the data; what problems remain in the data set?

  1. How well have the observations been checked?
    The positional information used on the Helikite and ground control point (GCP) datasets and metadata are available in the imagery and navigational components of the larger work citation. No color corrections were applied. GCP error in the Metashape project is used to assess overall error in the product. An additional vertical check was done with GPS points taken in a transect along the beach.
  2. How accurate are the geographic locations?
    Navigation information was acquired from a GNSS receiver (EMLID Reach M2) in PPK mode with a multi-band GNSS antenna that has a theoretical horizontal accuracy of 2 cm. However, using these values in Metashape returned a poor product so the accuracy was loosened to 10 cm and unchecked as positional control points to accommodate the unknown horizontal offset of the GPS to the camera and to rely more on the GCPs, which have a theoretical accuracy of 1-2 cm. The horizontal RMSE of the GCPs was xy: 0.022, 0.024 (m). The final product was compared to the previous survey at Head of the Meadow (see third cross-reference) and DSMs align at stable features.
  3. How accurate are the heights or depths?
    The location information was acquired from a GNSS receiver (EMLID Reach M2) in PPK mode with a multi-band GNSS antenna and hot shoe adapter with an estimated vertical accuracy of 5 cm. However, using these values in Metashape returned a poor product so the accuracy was loosened to 10 cm to rely more on the ground control points, which have a theoretical accuracy of 2-5 cm. The total vertical RMSE of the GCPs was 0.032 m. The final product was compared to the previous survey at Head of the Meadow Beach (see cross-reference) and the z differences at stable points were within 10 cm. The final product was also compared against 51 GPS points in a transect perindicular to the water line and the RMSE was 10 cm.
  4. Where are the gaps in the data? What is missing?
    The structure-from-motion process that builds the DSM and then the orthomosaic uses all the available imagery and location information at the start, however data holes may appear due to a lack of interpolation. Users are advised to read the rest of the metadata record carefully for additional details.
  5. How consistent are the relationships among the observations, including topology?
    There is one orthomosaic of Head of the Meadow Beach created from imagery in the larger work citation, the extent is greater than that of the digital surface model (DSM) in the larger citation because it includes water and edges that do not photogrammetrically reconstruct.

How can someone get a copy of the data set?

Are there legal restrictions on access or use of the data?
Access_Constraints None
Use_Constraints Public domain data from the U.S. Government are freely redistributable with proper metadata and source attribution. Please recognize the U.S. Geological Survey (USGS) as the source of this information.
  1. Who distributes the data set? (Distributor 1 of 1)
    U.S. Geological Survey - ScienceBase
    Denver Federal Center, Building 810, Mail Stop 302
    Denver, CO

    1-888-275-8747 (voice)
    sciencebase@usgs.gov
  2. What's the catalog number I need to order this data set? GeoTIFF file 2023-011-FA_Truro_DSM_UTM19N_NAVD88_25cm.tif is a 32-bit floating point digital surface model (DSM).
  3. What legal disclaimers am I supposed to read?
    Unless otherwise stated, all data, metadata and related materials are considered to satisfy the quality standards relative to the purpose for which the data were collected. Although these data and associated metadata have been reviewed for accuracy and completeness and approved for release by the U.S. Geological Survey (USGS), no warranty expressed or implied is made regarding the display or utility of the data for other purposes, nor on all computer systems, nor shall the act of distribution constitute any such warranty. Any use of trade, firm, or product names is for descriptive purposes only and does not imply endorsement by the U.S. Government. Although these data have been processed successfully on a computer system at the U.S. Geological Survey (USGS), no warranty expressed or implied is made regarding the display or utility of the data for other purposes, nor on all computer systems, nor shall the act of distribution constitute any such warranty. The USGS or the U.S. Government shall not be held liable for improper or incorrect use of the data described and/or contained herein.
  4. How can I download or order the data?
  5. What hardware or software do I need in order to use the data set?
    GIS software capable of reading a GeoTIFF.

Who wrote the metadata?

Dates:
Last modified: 25-Jul-2023
Metadata author:
Jin-Si R. Over
U.S. Geological Survey, Woods Hole Coastal and Marine Science Center
Geographer
U.S. Geological Survey
Woods Hole, MA

508-548-8700 x2297 (voice)
whsc_data_contact@usgs.gov
Contact_Instructions:
The metadata contact email address is a generic address in the event the person is no longer with USGS.
Metadata standard:
Content Standard for Digital Geospatial Metadata (FGDC-STD-001-1998)
This page is <https://cmgds.marine.usgs.gov/catalog/whcmsc/SB_data_release/DR_P9FYVLCD/2023011FA_Truro_DSM_metadata.faq.html>
Generated by mp version 2.9.51 on Wed Jul 26 11:10:00 2023