Lidar point cloud, elevation models, GPS data, imagery, and orthomosaic, collected during UAS operations at Town Neck Beach, Sandwich, MA on April 15th, 2024

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Frequently anticipated questions:

What does this data set describe?

Title:
Lidar point cloud, elevation models, GPS data, imagery, and orthomosaic, collected during UAS operations at Town Neck Beach, Sandwich, MA on April 15th, 2024
Abstract:
Small Uncrewed Aircraft Systems (sUAS) were used to collect aerial remote sensing data over Town Neck Beach, Massachusetts. The area is a highly trafficked public beach with a parking lot, boardwalk, and renourishment and dune stabilization plan. On April 15th, 2024, USGS personnel collected natural (RGB) color images, lidar, check points, and ground control points. These data were processed to produce a high-resolution lidar point cloud, digital elevation models, and a natural-color orthomosaic. Data are related to USGS Field activity 2024-018-FA and support observations of coastal change and lidar data testing.
Supplemental_Information:
For more information about the WHCMSC Field Activity, see https://cmgds.marine.usgs.gov/services/activity.php?fan=2024-018-FA. Images can be viewed or downloaded on the USGS Imagery Data System here https://cmgds.marine.usgs.gov/idsviewer/data_release/10.5066-P1UBZZFA in the collection 2024_TNB_Apr_YSMP. Note that the bounding coordinates are for the entire area and not individual files.
  1. How might this data set be cited?
    Over, Jin-Si R., and Cramer, Jennifer M., 2025, Lidar point cloud, elevation models, GPS data, imagery, and orthomosaic, collected during UAS operations at Town Neck Beach, Sandwich, MA on April 15th, 2024: data release DOI:10.5066/P1UBZZFA, 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., Cramer, Jennifer M., Farris, Amy, and Sherwood, Christopher R., 2025, Topographic data, imagery, and GPS data collected during uncrewed aircraft system (UAS) operations at Town Neck Beach, Sandwich, Massachusetts: data release DOI:10.5066/P1UBZZFA, U.S. Geological Survey, Reston, VA.

    Online Links:

    Other_Citation_Details:
    Over, J.R., Cramer, J.M., Farris, A., and Sherwood, C.R., 2025, Topographic data, imagery, and GPS data collected during uncrewed aircraft system (UAS) operations at Town Neck Beach, Sandwich, Massachusetts: U.S. Geological Survey data release, https://doi.org/10.5066/P1UBZZFA.
  2. What geographic area does the data set cover?
    West_Bounding_Coordinate: -70.48819822
    East_Bounding_Coordinate: -70.47310383
    North_Bounding_Coordinate: 41.77198992
    South_Bounding_Coordinate: 41.76130878
  3. What does it look like?
    https://www.sciencebase.gov/catalog/file/get/67213f45d34ed0f827eaaef0?name=2024018FA_TNB_Apr_data_browse.png&allowOpen=true (PNG)
    Data and products of Town Neck Beach: RGB image, lidar point cloud, ortho, and USGS personnel.
  4. Does the data set describe conditions during a particular time period?
    Calendar_Date: 15-Apr-2024
    Currentness_Reference:
    Ground condition
  5. What is the general form of this data set?
    Geospatial_Data_Presentation_Form: point cloud, raster, and tabular digital data
  6. How does the data set represent geographic features?
    1. How are geographic features stored in the data set?
    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?
    2024018FA_TNB_Apr_ImageLocations.csv
    The CSV file contains the approximate position of the YSMP images at the moment of each capture based on post-processed UAS integrated GPS/IMU. (Source: producer defined)
    ImageName
    File names of individual images, see the Process Description for file naming convention. (Source: USGS) Character string.
    GPSDateTime
    Date and UTC time in YYYY:MM:DD HH:MM:ss. (Source: Processor defined) Character string.
    Latitude NAD83[2011]
    Latitude (x) of camera based on time of each image capture. Positive values represent north coordinates. (Source: USGS)
    Range of values
    Minimum:41.76183024
    Maximum:41.77147449
    Units:decimal degrees
    Longitude NAD83[2011]
    Longitude (y) of camera based on time of each image capture. Negative values represent west coordinates. (Source: USGS)
    Range of values
    Minimum:-70.48772814
    Maximum:-70.47281292
    Units:decimal degrees
    Ellipsoid height GRS80
    Altitude of the camera at the time of each image capture relative to the NAD83(2011) reference ellipsoid (Source: None)
    Range of values
    Minimum:19.859
    Maximum:34.242
    Units:meters
    Easting 19N
    UTM X coordinate of camera based on time of each image capture. (Source: USGS)
    Range of values
    Minimum:376346.825
    Maximum:377574.562
    Units:meters
    Northing 19N
    UTM Y coordinate of camera based on time of each image capture. (Source: USGS)
    Range of values
    Minimum:4624384.857
    Maximum:4625471.845
    Units:decimal degrees
    Altitude NAVD88
    Altitude of the camera at the time of each image capture relative to NAVD88 with GEOID 18 applied. (Source: None)
    Range of values
    Minimum:48.040
    Maximum:62.416
    Units:meters
    2024018FA_TNB_Apr_AeroPoints.csv
    Ground control point positions, elevations, and attributes (Source: USGS)
    FAN
    USGS Field Activity Number (Source: USGS)
    ValueDefinition
    2024-018-FAYear, USGS ID, and Field Activity
    Date
    Calendar date of collection (Source: USGS)
    ValueDefinition
    20240415YYYYMMDD
    Point ID
    Unique point identification number. (Source: Processor defined)
    Range of values
    Minimum:1
    Maximum:6
    Attributes
    Unique identifier for ground control points. Prefix AP-### refers to AeroPoint and the last 3 digits of its identifying code. (Source: producer defined) Character string.
    Latitude NAD83[2011]
    Post-processed latitude of AeroPoint position (NAD83[2011]). (Source: USGS)
    Range of values
    Minimum:41.76489019
    Maximum:41.7680074
    Units:decimal degrees
    Longitude NAD83[2011]
    Post-processed longitude of AeroPoint position (NAD83[2011]). (Source: None)
    Range of values
    Minimum:-70.48537207
    Maximum:-70.47754726
    Units:decimal degrees
    Ellipsoid height GRS80
    Post-processed height in meters of AeroPoint in relation to the NAD83(2011) reference ellipsoid. (Source: None)
    Range of values
    Minimum:-28.303
    Maximum:-22.993
    Units:meters
    Easting 19N
    Post-processed interpolated X-coordinate of AeroPoint in NAD83(2011)/UTM Zone 19N. (Source: USGS)
    Range of values
    Minimum:376537.628
    Maximum:377182.087
    Units:meters
    Northing 19N
    Post-processed interpolated Y-coordinate of AeroPoint in NAD83(2011)/UTM Zone 19N. (Source: USGS)
    Range of values
    Minimum:4624727.722
    Maximum:4625085.026
    Units:meters
    Orthometric height NAVD88
    Post-processed Z-coordinate of AeroPoint using NAVD88 with GEOID 18 applied. (Source: USGS)
    Range of values
    Minimum:-0.126
    Maximum:5.193
    Units:meters
    Xvar mm
    Internal variance in the X-coordinate from post-processing. (Source: producer defined)
    Range of values
    Minimum:1.7
    Maximum:5.0
    Units:millimeters
    Yvar mm
    Internal variance in the Y-coordinate from post-processing. (Source: producer defined)
    Range of values
    Minimum:1.4
    Maximum:6.5
    Units:millimeters
    Zvar mm
    Internal variance in the Z-coordinate from post-processing. (Source: producer defined)
    Range of values
    Minimum:2.9
    Maximum:13.1
    Units:millimeters
    Baseline distance km
    Distance to from the AeroPoint to the correcting base. (Source: producer defined)
    Range of values
    Minimum:0.33
    Maximum:11.92
    Units:kilometers
    2024018FA_TNB_Apr_GPS_SP80.csv
    GPS SP80 check point positions, elevations, and attributes (Source: USGS)
    FAN
    USGS Field Activity Number (Source: USGS)
    ValueDefinition
    2024-018-FAYear, USGS ID, and Field Activity
    Date
    Calendar date of collection (Source: USGS)
    ValueDefinition
    20240415YYYYMMDD
    Point ID
    Unique point identification number. (Source: Processor defined)
    Range of values
    Minimum:1
    Maximum:77
    Attributes
    Identifies check point type. This includes T# for Transect and number, groin, parking lot, boardwalk, grass, stick, camera, roses, and AeroPoint (AP). (Source: producer defined) Character string.
    Latitude NAD83[2011]
    Post-processed latitude of AeroPoint position (NAD83[2011]). (Source: USGS)
    Range of values
    Minimum:41.76480479
    Maximum:41.76872862
    Units:decimal degrees
    Longitude NAD83[2011]
    Post-processed longitude of AeroPoint position (NAD83[2011]). (Source: None)
    Range of values
    Minimum:-70.48538118
    Maximum:-70.47552819
    Units:decimal degrees
    Ellipsoid height GRS80
    Post-processed height in meters of AeroPoint in relation to the NAD83(2011) reference ellipsoid. (Source: None)
    Range of values
    Minimum:-29.340
    Maximum:-21.415
    Units:meters
    Easting 19N
    Post-processed interpolated X-coordinate of AeroPoint in NAD83(2011)/UTM Zone 19N. (Source: USGS)
    Range of values
    Minimum:376537.707
    Maximum:377350.157
    Units:meters
    Northing 19N
    Post-processed interpolated Y-coordinate of AeroPoint in NAD83(2011)/UTM Zone 19N. (Source: USGS)
    Range of values
    Minimum:4624715.780
    Maximum:4625164.250
    Units:meters
    Orthometric height NAVD88
    Post-processed Z-coordinate of AeroPoint using NAVD88 with GEOID 18 applied. (Source: USGS)
    Range of values
    Minimum:-1.168
    Maximum:6.772
    Units:meters
    HSDV m
    Horizontal standard deviation, provides the horizontal precision of the position solution. (Source: producer defined)
    Range of values
    Minimum:0.008
    Maximum:0.033
    Units:meters
    VSDV m
    Vertical standard deviation, provides the vertical precision of the position solution. (Source: producer defined)
    Range of values
    Minimum:0.014
    Maximum:0.054
    Units:meters
    2024018FA_TNB_Apr_YSMP_LPC.laz
    YSMP lidar point cloud in .laz file format. This georeferenced point cloud was colorized using natural color RGB image values and is not classified. Total point count is 117,127,028. The point density is 310.1 points per square meter, and point spacing is 0.057 m. (Source: producer defined)
    Elevation
    Surface elevation orthometric height NAVD88 (m) using GEOID 18 in NAD83(2011)/UTM Zone 19N. (Source: YellowScan CloudStation)
    Range of values
    Minimum:-2.100
    Maximum:14.891
    Units:meters
    Intensity
    Lidar intensity is recorded as the return strength of a laser beam during data collection. (Source: YellowScan CloudStation)
    Range of values
    Minimum:0
    Maximum:65,025
    2024018FA_TNB_Apr_YSMP_DSM_25cm.tif
    A cloud-optimized digital surface model gridded from the lidar point cloud with encoded elevation values. 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)
    Range of values
    Minimum:-2.141
    Maximum:14.914
    Units:meters
    2024018FA_TNB_Apr_YSMP_SfM_DSM_25cm.tif
    A cloud-optimized SfM digital surface model made from the lidar point cloud images. 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)
    Range of values
    Minimum:-6.982
    Maximum:15.023
    Units:meters
    2024018FA_TNB_Apr_YSMP_SfM _Ortho_5cm.tif
    True-color (RGB) cloud optimized orthomosaic made from the YSMP images. (Source: USGS)
    Band_1
    Red wavelength band (Source: Agisoft Metashape)
    Range of values
    Minimum:0
    Maximum:255
    Band_2
    Green wavelength band (Source: Agisoft Metashape)
    Range of values
    Minimum:0
    Maximum:255
    Band_3
    Blue wavelength band (Source: Agisoft Metashape)
    Range of values
    Minimum:0
    Maximum:255
    Entity_and_Attribute_Overview:
    The filenames are formatted as "2024018FA_TNB_Apr_sensor/product_ resolution.*** ", where 2024018 is the USGS Field activity ID, location is Town Neck Beach (TNB); sensors include YellowScan Mapper Plus (YSMP), GPS_SP80, and AeroPoints; products include structure from motion (SfM) orthomosaics (ortho), digital surface models (DSM), and lidar point cloud (LPC). The horizontal coordinate reference system for all products is NAD83(2011)/UTM19N, the vertical coordinate reference system (VCRS) is NAVD88 using GEOID 18.
    Entity_and_Attribute_Detail_Citation: USGS Field Activity 2024-018-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
    • Jennifer M. Cramer
  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, Northeast Region, 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?

The imagery and lidar products were produced to help monitor the movement of sand placed on the beach by the US Army Corps of Engineers in the fall of 2023. These data will also be used to test the ability of the lidar data to penetrate both newly planted dune grass as well as more mature vegetation compared to structure from motion products. The data will also be used to measure the seasonal variability of beach slope and shoreline position.

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: 15-Apr-2024 (process 1 of 6)
    GROUND CONTROL: Ten AeroPoint GCPs were spaced out over the field site and left on for at least two hours to collect Global Navigation Satellite System(GNSS) data, however four were not properly turned on. After collection and connected to Wi-Fi, the AeroPoint data were uploaded and run through a post-processing kinematic algorithm of the Continuously Operating Reference Station (CORS) network to get a global accuracy. The data were exported with xyz internal variances in the horizontal datum NAD83(2011) to produce latitude, longitude, and ellipsoid heights, and then UTM19N and NAVD88 using GEOID 18 was used to produce easting, northing, and orthometric heights. These were exported to a *.csv file and named 2024018FA_TNB_Apr_AeroPoints.csv. GPS DATA: A Spectra Precision 80 (SP80) was set up as a base station in the parking lot to collect RINEX data to correct the lidar data. A second SP80 was set up as a rover connected to the Massachusetts CORS network and used to take check shots across the study site. The check points are provided in 2024018FA_TNB_Apr_GPS_SP80.csv. Step completed by C. Sherwood, A. Farris, J. Cramer, and J. Over.
    Date: 15-Apr-2024 (process 2 of 6)
    UAS FLIGHTS: The LiDAR sensor was a 905 nm wavelength Livox Avia with a 70.4/ 4.5 degree horizontal and vertical field of view (FOV). The LiDAR scanner was set to the repetitive scan pattern, which moves the sensor in a back-and-forth motion and is optimal for non-vegetated areas. The camera module was a SONY UMC - 10RC, a 20.4 megapixel (MP). The system also consists of a Trimble AV18 GNSS antenna mounted to the top of the UAS and connected to the LiDAR system via GNSS cable. The LiDAR data was saved to a 256 GB USB thumb drive in three different files: (1) the IMU+GPS data, decimated for quick post-processing, in binary *.ys format, (2) the scanner data in *.lvx format (~600 MB per minute of data collection), (3) and the complete IMU+GPS data in Applanix (Trimble) binary *.t04 format. The RGB images were saved to a 64 GB micro SD card as *.jpeg files. A configuration text file (CONFIG.TXT) was pre-loaded onto the USB thumb drive and can be edited to control LiDAR and camera module settings, including the camera triggering height, the camera triggering interval, and the LiDAR scan pattern. The YSMP was attached to a DJI Matrice 600 Pro UAS with approved government edition firmware. The YSMP lidar data were collected with the UAS flying at 7 m/s at ~61 meters above ground level at a transect spacing of 45 m for a total of 42 minutes of flight time. The SONY camera triggered every 2 seconds. After each flight the lidar data were taken off the sensor. Note, the geotagged positions embedded in the Exif information are WGS84 and ellipsoid height, this is how the data are collected. The positions have been converted to NAD83(2011) and NAVD88 GEOID 18 in the imagery locations file (2024018FA_TNB_Apr_ImageryLocations.csv). Step completed by J. Cramer and J. Over.
    Date: 16-Apr-2024 (process 3 of 6)
    RAW IMAGERY: YSMP images were processed to add additional information required by the USGS to the EXIF headers using ExifTools (https://exiftool.org/, version: 12.06), and the files were renamed to a unique identifier using Namexif (http://www.digicamsoft.com/softnamexif.html, version 2.1) to avoid any possibility of duplicate names. These steps are described here. 1. ExifTools was used to tag each photo headers following the Imagery Data System EXIF Guidance. Attributes (e.g. Credit, Copyright, UsageTerms, ImageDescription, Artist, etc) were stored in a *.csv file and written to each image with the command:' exiftool -csv="C:\directory\name\EXIF.csv" C:\directory\name\of\photos *.JPG ' To read out the photo information to a csv when in the directory with the photos the command is: exiftool -csv *.JPG > directory/name/allheaders_out.csv 2. All the images were renamed with Namexif (https://us.digicamsoft.com/softnamexif.html v 2.2 accessed April 2020) to ensure unique filenames and compliance with the USGS Coastal and Marine Hazards and Resources Program's best practices for image naming convention. Images were renamed with the field survey ID prefix; flight number, and ID that distinguishes USGS cameras by make/camera number, the image acquisition date, coordinated universal time (UTC) in ISO8601 format, and a suffix with the original image name. For example, image name '2024018FA_f01r03_20240415T165822Z_DSC#', 2024018FA is the field activity ID, f01 is the flight number, r03 is the camera, 20240415 is the UTC date in the format YYYYMMDD, and a 'T' is used to separate UTC date from UTC time in format HHMMSS followed by a Z. The DSC# is the original raw photo name appended to the end of the new filename. Step completed by J. Cramer and J. Over.
    Date: 06-Dec-2024 (process 4 of 6)
    PHOTOGRAMMETRY: The SfM products were 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. A project was created in Metashape and YSMP imagery was imported. 2. Photos were aligned at a low accuracy and then GCPs were automatically detected in the point cloud. GCP positions (2024018FA_TNB_Apr_AeroPoints.csv) were added to the project in the reference systems NAD83(2011)/UTM Zone 19N and NAVD88 (GEOID 18). The horizontal and vertical accuracies for the GCPs were set to 0.04/0.02 m, respectively, and the camera positions for the images were turned off. The photos were then re-aligned with high accuracy (the pixels were not subsampled) using a keypoint limit of 60,000 and unlimited tie points. 3. The alignment process matched pixels between images to create point clouds and put the imagery into a relative spatial context using the GCPs. The resultant point clouds were filtered using one iteration of the 'Reconstruction uncertainty' filter at a level of 10, one iteration of the 'Projection accuracy' filter at a level of 3, and eight iterations of the 'Reprojection accuracy' filter to get to a level of 0.3. With each filter, iteration points are selected, deleted, and then the camera model was optimized to refine the focal length, cx, cy, k1, k2, k3, p1, and p2 camera model coefficients. 4. At this point, multiple ‘chunks’ were created so that a high-quality dense cloud with a low-frequency filtering algorithm could be made from the images. The dense point cloud was then edited by visual inspection and Metashape’s confidence filter to remove points with a low confidence near the edges and near water bodies. 5. A DSM is built from the dense point cloud and then an orthomosaic is built from the DSM with refined seamlines. The DSM (2024018FA_TNB_Apr_YSMP_SfM_DSM_25cm.tif) and orthomosaic (2024018FA_TNB_Apr_YSMP_SfM_Ortho_5cm.tif) are exported in EPSG:6348 NAD83(2011)/UTM19N, the DSM has a vertical reference system in EPSG:5703 NAVD88 (GEOID 18). Step completed by J. Over.
    Date: 02-Nov-2024 (process 5 of 6)
    LIDAR DATA: The YSMP lidar data were processed in YellowScan CloudStation software integrated with Trimble POSPac UAV 9.0. Base station GNSS data were downloaded from the SP80 collecting data on site for the time the UAS was flying. Raw scanner data (.ys file) was imported into YellowScan CloudStation, the sensor lidar (.profile) and Camera (.camera) profiles, provided by the vendor, were selected for the project and the project coordinate reference system is set. CloudStation flight trajectories are adjusted manually to select the desired data to be processed. The .T04 file and base station GNSS RINEX file were used to correct and optimize the sensor position trajectories and produce a Smoothed Best Estimate of Trajectory (SBET) file in .txt ASCII format, which represents the Post Processing Kinematic (PPK) Solution. The lever arm offsets and boresight angle corrections were applied to the lidar point cloud (LPC), along with a strip adjustment between transect swaths using CloudStation's "robust" setting. The LPC is then colorized using the images. The Cut Overlap function was applied to remove redundant points based on the closest parallel flight trajectory. The unclassified LPC model is exported from CloudStation as a 1.4 *.laz file. The LPC is brought into Global Mapper (v. 26.0) and manually cleaned of points interpreted to be noise or are above a reasonable elevation threshold based on the surrounding features. Then, the LPC is adjusted to the GCPs using a planar fit and exported as 2024018FA_TNB_Apr_YSMP_LPC.laz. The LPC is then gridded using maximum values and exported (2024018FA_TNB_Apr_YSMP_DSM_25cm.tif). All files were exported in EPSG:6348 NAD83(2011)/UTM zone 19N and the vertical datum in EPSG:5703 NAVD88 using GEOID 18. Step completed by J. Over.
    Date: 06-Dec-2024 (process 6 of 6)
    CLOUD OPTIMIZATION: All GeoTIFF products were DEFLATE compressed and turned into a cloud-optimized GeoTIFFs (COG) using gdal_translate with the following command: for %i in (.\*.tif) do gdal_translate %i .\cog\%~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. Step completed by J. Over. Person who carried out this activity:
    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)
    jover@usgs.gov
  3. What similar or related data should the user be aware of?
    Over, Jin-Si R., Ritchie, Andrew C., Kranenburg, Christine J., Brown, Jenna A., Buscombe, Daniel D., Noble, Tom, Sherwood, Christopher R., Warrick, Jonathan A., and Wernette, Phillipe A., 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 surface models and ortho products.

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

  1. How well have the observations been checked?
    The horizontal and vertical accuracy of the elevation products (2024018FA_TNB_Apr_YSMP_LPC.laz, 2024018FA_TNB_Apr_YSMP_DSM_25cm.tif, 2024018FA_TNB_Apr_YSMP_SfM_DSM_25cm.tif, and 2024018FA_TNB_Apr_YSMP_SfM_Ortho_5cm.tif) were assessed using the ground control points (GCPs; 2024018FA_TNB_Apr_AeroPoints.csv) and GPS check points (2024018FA_TNB_Apr_GPS_SP80.csv). It should also be noted that accuracy estimates of the products are for areas of bare ground or low vegetation where GCPs were placed or GPS points taken, vertical errors are tied to horizontal errors, especially near places such as a scarp. Additional sources of error, such as moving objects or poor overlap near the edges of the survey and away from GCPs may cause accuracy estimates to exceed estimates in localized portions of the products. Lidar flight paths are corrected using a base station. Note that any lidar returns over water reflect the surface, not the bottom, while the structure from motion (SfM) digital surface model (DSM) does reconstruct a surface below the water. GPS point accuracy is assessed based on occupations of a known reference mark and GPS point precision is based on a positioning solution of “FIX” for each point.
  2. How accurate are the geographic locations?
    The GCPs and GPS points have a horizontal accuracy of 4 cm. The LPC, and by association the lidar derived DSM, horizontal accuracy was assessed against positions of the AeroPoints. The horizontal accuracy is variable; based on intensity the AeroPoint centers are on average 20 cm from the known position. It is recommended that users do their own assessment for their own needs. The SfM products were spatially georeferenced using AeroPoints and created using Agisoft Metashape. The horizontal root mean square error (RMSE) of the GCPs (n=6) as reported from the Metashape project are x/y 0.054/0.091 m.
  3. How accurate are the heights or depths?
    The GCPs and GPS points have a vertical accuracy of 2 cm. The LPC and by association the lidar derived DSM, was assessed against the USGS 3DEP (https://www.usgs.gov/3d-elevation-program) surface in the parking lot and values fall within 10 cm. The LPC was also assessed against the elevations of the AeroPoints and GPS points, and the RMSE (n=83) was 0.113 m. The SfM DSM vertical RMSE as reported from the Metashape project GCPs (n=6) is 0.060 m. The vertical RMSE compared to the GPS check points (n=83) = 0.327 m. This larger vertical error is driven by points (n=11) on the edge of the DSM where there is poor ground control, with these outlier check points removed, the RMSE = 0.157 m. Users should take care to check where the DSMs diverge.
  4. Where are the gaps in the data? What is missing?
    Imagery: Images at take-off and landing were removed. All of these removed images can account for the non-consecutive original file names and results in a total of 688 images. A list of the images and their locations are available in 2024018FA_TNB_Apr_ImageLocations.csv. Lidar: Points were removed from the LPC in the water where they were sparse. Points identified as flying birds were also removed. LPC is not classified. Products: GeoTIFF products are cloud-optimized and deflate compressed. GPS: Four AeroPoints did not collect data but show up in the imagery. This causes the SfM products to have a lower positional accuracy than expected due to the poor spatial distribution of the working GCPs.
  5. How consistent are the relationships among the observations, including topology?
    There were two UAS M600 flights that used the YellowScan Mapper+ (YSMP) to collect lidar data and images and produced the lidar point cloud (LPC) and gridded DSM. The images taken by the YSMP were also used to create a SfM DSM and orthomosaic. Ten AeroPoints were placed, but only six were properly turned on. A SP80 GPS rover was used to take 77 ground check points. All data fall into expected elevation ranges of a low-lying beach and dune system.

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 (CC0-1.0) 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. These data are not intended for navigational use.
  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? Aerial imaging and mapping of Town Neck Beach includes a lidar point cloud, elevation models, imagery and true-color orthomosaic, and ground control and check points.
  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. Not for navigational use.
  4. How can I download or order the data?

Who wrote the metadata?

Dates:
Last modified: 30-Apr-2025
Metadata author:
Jin-Si R. Over
U.S. Geological Survey, Northeast Region
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_P1UBZZFA/2024-018-FA_TNB_Apr_meta.faq.html>
Generated by mp version 2.9.51 on Wed Apr 30 15:47:22 2025