Digital surface models representing Nauset Light Beach, Eastham, MA on September 14 and 20, 2023, pre and post Hurricane Lee

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Frequently anticipated questions:

What does this data set describe?

Title:
Digital surface models representing Nauset Light Beach, Eastham, MA on September 14 and 20, 2023, pre and post Hurricane Lee
Abstract:
The data in this release map Marconi Beach, Head of the Meadow Beach, and Nauset Light Beach, in Cape Cod National Seashore (CACO), Massachusetts, before and after Hurricane Lee in September 2023. U.S Geological Survey personnel conducted field surveys to collect topographic data using global navigation satellite systems (GNSS) at all three beaches. In addition, at Nauset Light Beach, an uncrewed aerial system (UAS) was used to collect images with a Ricoh GRII camera for use in structure from motion photogrammetry. High-precision GNSS targets (AeroPoints) were used as ground control points (GCPs) for the UAS photogrammetry. Agisoft Metashape (v. 2.0.1) software was used to create a digital surface model and an orthomosaic from the collected imagery and GCPs. Photos were taken with smartphones for environmental context. This work was conducted under National Park Service Research Permit CACO-2020-SCI-0021.
Supplemental_Information:
For more information about the WHCMSC Field Activity, see https://cmgds.marine.usgs.gov/fan_info.php?fan=2023-022-FA. These data are also related to USGS field activity 2023-023-FA, which collected pressure-sensor measurements at these three beaches.
  1. How might this data set be cited?
    U.S. Geological Survey, 20231204, Digital surface models representing Nauset Light Beach, Eastham, MA on September 14 and 20, 2023, pre and post Hurricane Lee: data release DOI:10.5066/P9GA5RJD, 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., Anderberg, Mira M., Bartlett, Marie K., and Cramer, Jennifer M., 2023, Topographic data, imagery, and ground control data collected at Head of the Meadow, Marconi, and Nauset Light beaches, Cape Cod National Seashore, Massachusetts in September 2023, pre and post Hurricane Lee: data release DOI:10.5066/P9GA5RJD, U.S. Geological Survey, Reston, VA.

    Online Links:

    Other_Citation_Details:
    Over, J.R., Sherwood, C.R., Anderberg, M.M., Bartlett, M.K., and Cramer, J.M., 2023, Topographic data, imagery, and ground control data collected at Head of the Meadow, Marconi, and Nauset Light beaches, Cape Cod National Seashore, Massachusetts in September 2023, pre and post Hurricane Lee: U.S Geological Survey data release, https://doi.org/10.5066/P9GA5RJD.
  2. What geographic area does the data set cover?
    West_Bounding_Coordinate: -69.95371393
    East_Bounding_Coordinate: -69.95031291
    North_Bounding_Coordinate: 41.86217059
    South_Bounding_Coordinate: 41.85615483
  3. What does it look like?
    https://www.sciencebase.gov/catalog/file/get/650dca5bd34e823a02745a6c?name=2023022FA_HxLee_DSM_browse.JPG&allowOpen=true (JPEG)
    Elevation-colored image of topography data collected on Nauset Light Beach, Eastham, MA in September 2023.
  4. Does the data set describe conditions during a particular time period?
    Calendar_Date: 14-Sep-2023
    Currentness_Reference:
    ground condition; represents the state of the beach on September 14 and 20, 2023.
  5. What is the general form of this data set?
    Geospatial_Data_Presentation_Form: raster digital data
  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, 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 0.05
      Ordinates (y-coordinates) are specified to the nearest 0.05
      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 6378137.000000.
      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, geoid 18
      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?
    2023022FA_NLB_preHxLee_DSM_UTM19N_NAVD88_5cm_cog.tif
    A raster dataset (cloud-optimized GeoTIFF format) with encoded elevation values of Nauset Light Beach in Eastham, MA before Hurricane Lee on September 14, 2023. Pixel resolution is 5 cm. (Source: producer defined)
    Value
    Surface elevation orthometric height NAVD88 (m) using Geoid 2018 (Source: Producer defined)
    ValueDefinition
    -3.4028234663852886e38No data
    Range of values
    Minimum:-0.690
    Maximum:25.000
    Units:meters
    2023022FA_NLB_postHxLee_DSM_UTM19N_NAVD88_5cm_cog.tif
    A raster dataset (cloud-optimized GeoTIFF format) with encoded elevation values of Nauset Light Beach in Eastham, MA before Hurricane Lee on September 20, 2023. Pixel resolution is 5 cm. (Source: Producer defined)
    Value
    Surface elevation orthometric height NAVD88 (m) using Geoid 2018 (Source: Producer defined)
    ValueDefinition
    -3.4028234663852886e38No data
    Range of values
    Minimum:-0.500
    Maximum:25.000
    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 "2023022FA_NLB_preHxLee_DSM_UTM19N_NAVD88_5cm_cog.tif", where 2023022 is the USGS Field activity ID, location is Nauset Light Beach (NLB), pre or post Hurricane Lee (HxLee), DSM is Digital Surface Model, UTM19N_NAVD88 is the horizontal and vertical coordinate reference system, 5cm indicates the resolution of the grid, and cog is cloud optimized GeoTIFF.
    Entity_and_Attribute_Detail_Citation: USGS Field Activity 2023-022-FA

Who produced the data set?

  1. Who are the originators of the data set? (may include formal authors, digital compilers, and editors)
    • U.S. Geological Survey
  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?

Digital surface models (DSM) are part of an elevation dataset of Nauset Light Beach for use by the public, researchers, and others to observe ground conditions and detect change before and after Hurricane Lee.

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: Sep-2023 (process 1 of 1)
    Digital Surface Model was created in Agisoft Metashape v. 2.0.1 using the following general steps (see Over and others, 2021 for a more detailed methodology explanation):
    1. The project was created and imagery (located in larger work citation 2023022FA_NLB_preHxLee_imagery.zip and 2023022FA_NLB_postHxLee_imagery.zip) were imported using the NAD83(2011)/UTM19N and NAVD88 datums.
    2. Photos were aligned at a low accuracy so that GCPs could be automatically detected in the point cloud. Eight GCPs (2023022FA_NLB_preHxLee_AeroPoints.csv and 2023022FA_NLB_postHxLee_AeroPoints.csv located in the larger work citation) were found in the images and then added to the project in the reference systems NAD83(2011)/UTM Zone 19N and NAVD88. Accuracies for the GCPs were set 0.02 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. The alignment process matches pixels between images to create point clouds and puts the imagery into a relative spatial context using the photo positions and GCPs. Then, Metashape software refined and optimized, using least squares, the camera positions and lens model using gradual selection and optimization parameters of: Ru = 20, Pa = 5, and Re = 0.3 to minimize the reprojection error or the distance between the measured points and the software created points. 4. The pre and post Hurricane Lee point clouds were separated into individual Metashape chunks. A dense point cloud was generated using the high-quality setting (images were not subsampled) and a low frequency filtering algorithm for the pre and post images. Each dense point cloud was then hand edited to remove noise before generating digital elevation models (the software calls all models elevation models, but a surface model includes vegetation/canopy returns, a terrain model would be only bare earth returns). 5. The pre and post DSM products were exported at 5 cm in NAD83(2011)/UTM Zone 19N and NAVD88 (m). 6. The DSMs were then turned into cloud-optimized GeoTIFFs (COG) using gdal_translate with the following command: for %i in (.\*.tif) do gdal_translate %i .\%~ni_cog.tif -of COG -stats -co BLOCKSIZE=256 -co COMPRESS=DEFLATE -co PREDICTOR=YES -co NUM_THREADS=ALL_CPUS -co BIGTIFF=YES (v. 3.1.4 accessed October 20, 2020 https://gdal.org/), where i is the name of each GeoTIFF section. 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., Ritchie, Andrew C., Kranenburg, Christine, Jennifer (Jenna) A. Brown, Buscombe, Daniel D., Noble, Tom, Sherwood, Christopher R., Warrick, Jonathan, and Wernette, Phillipe, 2021, Processing coastal imagery with Agisoft Metashape Professional Edition, version 1.6—Structure from motion workflow documentation: Open-File Report 2021-1039, U.S. Geological Survey, Reston, VA.

    Online Links:

    Other_Citation_Details:
    This publication includes the general methodology for processing imagery in Metashape to produce digital elevation models and ortho products.

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

  1. How well have the observations been checked?
    Ground control points (GCPs) were used to constrain the products – see associated metadata for details. GCP error in the Metashape project is used to assess overall error in the product. There is high confidence that the products are accurate to or better than 5 cm.
  2. How accurate are the geographic locations?
    The AeroPoint GCPs have a theoretical horizontal accuracy of 2 cm. The horizontal RMSE of the GCPs (n=8) was xy: 0.005, 0.005 (m).
  3. How accurate are the heights or depths?
    The AeroPoint GCPs have a theoretical vertical accuracy of 1 cm. The total vertical RMSE of the GCPs (n=8) was 0.010 m. The pre storm DSM was compared to the GPS transect points taken the day before (see larger work citation), and the RMSE of the points (n=17) compared to the DSM was 0.031 m.
  4. Where are the gaps in the data? What is missing?
    The structure-from-motion process that builds the DSM uses all the available imagery, however not all images may align in the software to produce the final product. This model does not interpolate elevation data over holes. The model was clipped in Agisoft Metashape to remove areas of poor interpolation near the edges of the raster.
  5. How consistent are the relationships among the observations, including topology?
    All data fall into expected elevation ranges compared to GPS transect points (see larger work citation) except for points near and offshore of the waterline, where the data returned can be noisy and may result in erroneous measurements. This is a digital surface model (DSM) and includes returns from vegetation.

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 files are 32-bit floating point cloud-optimized DSMs.
  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, the internal organization of the file allows it to be used more efficiently in the cloud environment.

Who wrote the metadata?

Dates:
Last modified: 04-Dec-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_P9GA5RJD/2023022FA_HxLee_DSM_metadata.faq.html>
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