Lidar point cloud, elevation models, GPS data, and imagery and orthomosaic from true-color aerial imagery, collected during UAS operations at Marsh Island, New Bedford, MA on March 11, 2025

Metadata also available as - [Outline] - [Parseable text] - [XML]

Frequently anticipated questions:

What does this data set describe?

Title:
Lidar point cloud, elevation models, GPS data, and imagery and orthomosaic from true-color aerial imagery, collected during UAS operations at Marsh Island, New Bedford, MA on March 11, 2025
Abstract:
Small Uncrewed Aircraft Systems (sUAS) were used to collect aerial remote sensing data over Marsh Island, a salt marsh restoration site along New Bedford Harbor, Massachusetts. Remediation of the site will involve direct hydrological and geochemical monitoring of the system alongside the UAS remote sensing data. On March 11th, 2025, USGS personnel collected natural (RGB) color images, lidar, and ground control points. These data were processed to produce a high-resolution lidar point cloud (LPC), digital elevation models (surface and terrain), and a natural color orthomosaic.
Supplemental_Information:
For more information about the WHCMSC Field Activity, see https://cmgds.marine.usgs.gov/services/activity.php?fan=2025-009-FA. Images can be viewed or downloaded on the USGS Imagery Data System (IDS) here https://doi.org/10.5066/P14MGKBY in the collection 2025_MI_Mar_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 Millo, Amit, 2026, Lidar point cloud, elevation models, GPS data, and imagery and orthomosaic from true-color aerial imagery, collected during UAS operations at Marsh Island, New Bedford, MA on March 11, 2025: data release DOI:10.5066/P19TLXVG, 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., Millo, Amit, Brosnahan, Sandra M., Ackerman, Seth D., and Ganju, Neil Kamal, 2024, Topographic, multispectral, and GPS data collected during uncrewed aircraft system (UAS) operations at Marsh Island, New Bedford, Massachusetts (ver. 2.0, May 2026): data release DOI:10.5066/P19TLXVG, U.S. Geological Survey, Reston, VA.

    Online Links:

    Other_Citation_Details:
    Suggested citation: Over, J.R., Cramer, J.M., Millo, A., Brosnahan, S.M., Ackerman, S.D., and Ganju, N.K., 2024, Topographic, multispectral, and GPS data collected during uncrewed aircraft system (UAS) operations at Marsh Island, New Bedford, Massachusetts (ver. 2.0, May 2026): U.S. Geological Survey data release, https://doi.org/10.5066/P19TLXVG.
  2. What geographic area does the data set cover?
    West_Bounding_Coordinate: -70.91838350
    East_Bounding_Coordinate: -70.91345827
    North_Bounding_Coordinate: 41.65458340
    South_Bounding_Coordinate: 41.64991244
  3. What does it look like?
    https://www.sciencebase.gov/catalog/file/get/695fe08bd4be024e3af50553?name=2025009FA_MI_Mar_data_browse.jpg&allowOpen=true (JPEG)
    Data and products of Marsh Island: RGB image, lidar point cloud, ortho, digital surface model (DSM), and digital terrain model (DTM).
  4. Does the data set describe conditions during a particular time period?
    Calendar_Date: 11-Mar-2025
    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?
    2025009FA_MI_Mar_YSMP_ImageLocations.csv
    The CSV file contains the approximate position of the YSMP camera at the moment of each image capture. (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 in UTC time. (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:41.65030593
    Maximum:41.65394153
    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:-70.91793527
    Maximum:-70.91423070
    Units:decimal degrees
    Altitude NAD83[2011] ellipsoid
    Altitude of the camera position at the time of each image capture relative to the NAD83(2011) GRS80 ellipsoid. (Source: Processor defined)
    Range of values
    Minimum:33.490
    Maximum:40.787
    Units:meters
    Northing 19N
    Y-coordinate of camera image in NAD83(2011)/UTM Zone 19N. (Source: USGS)
    Range of values
    Minimum:4612723.891
    Maximum:4613124.933
    Units:meters
    Easting 19N
    X-coordinate of camera image in NAD83(2011)/UTM Zone 19N. (Source: USGS)
    Range of values
    Minimum:340292.003
    Maximum:340608.270
    Units:meters
    Altitude NAVD88
    Altitude of the camera position at the time of each image capture relative to NAVD88 with GEOID 18 applied. (Source: USGS)
    Range of values
    Minimum:62.652
    Maximum:69.950
    Units:meters
    2025009FA_MI_Mar_AeroPoints.csv
    Ground control point positions, elevations, and attributes (Source: USGS)
    FA
    USGS Field Activity Number (Source: USGS)
    ValueDefinition
    2025-009-FAYear, USGS ID, and Field Activity
    Date
    Calendar date of collection (Source: USGS)
    ValueDefinition
    20250311YYYYMMDD
    Point ID
    Unique point identification number. (Source: Processor defined)
    Range of values
    Minimum:1
    Maximum:10
    Attributes
    Unique identifier for ground control points. Prefix AP-### refers to AeroPoint and the last 3 digits of its identifying code. (Source: Processor defined) Character string.
    Latitude NAD83[2011]
    Post-processed latitude (x-coordinate) of AeroPoint position (NAD83[2011]). (Source: USGS)
    Range of values
    Minimum:41.65118336
    Maximum:41.65268968
    Units:decimal degrees
    Longitude NAD83[2011]
    Post-processed longitude (y-coordinate) of AeroPoint position (NAD83[2011]). Negative values represent West coordinates. (Source: USGS)
    Range of values
    Minimum:-70.91768289
    Maximum:-70.91414052
    Units:decimal degrees
    Ellipsoid height GRS80
    Post-processed height in meters of AeroPoint in relation to the NAD83(2011) reference GRS80 ellipsoid. (Source: Processor defined)
    Range of values
    Minimum:-28.390
    Maximum:-26.667
    Units:meters
    Northing 19N
    Post-processed interpolated Y-coordinate of AeroPoint in NAD83(2011)/UTM Zone 19N. (Source: USGS)
    Range of values
    Minimum:4612822.603
    Maximum:4612985.752
    Units:meters
    Easting 19N
    Post-processed interpolated X-coordinate of AeroPoint in NAD83(2011)/UTM Zone 19N. (Source: USGS)
    Range of values
    Minimum:340315.512
    Maximum:340612.837
    Units:meters
    Orthometric height NAVD88
    Post-processed Z-coordinate of AeroPoint using NAVD88 with GEOID 18 applied. (Source: USGS)
    Range of values
    Minimum:0.776
    Maximum:2.502
    Units:meters
    Xvar mm
    Variance in the X-coordinate from post-processing (Source: Propeller)
    Range of values
    Minimum:2.1
    Maximum:4.4
    Units:millimeters
    Yvar mm
    Variance in the Y-coordinate from post-processing (Source: Propeller)
    Range of values
    Minimum:0.6
    Maximum:4.4
    Units:millimeters
    Zvar mm
    Variance in the Z-coordinate from post-processing (Source: Propeller)
    Range of values
    Minimum:3.2
    Maximum:7
    Units:millimeters
    Baseline distance km
    distance of AeroPoint from nearest used processing network base station (Source: Propeller)
    Range of values
    Minimum:0.06
    Maximum:9.39
    Units:kilometers
    2025009FA_MI_Mar_GPS_Emlid_RS3_checkpoints.csv
    GPS check point shots, elevations, and errors (Source: USGS)
    FA
    USGS Field Activity Number (Source: USGS)
    ValueDefinition
    2025-009-FAYear, USGS ID, and Field Activity
    Date
    Calendar date of collection (Source: USGS)
    ValueDefinition
    20250311YYYYMMDD
    Point ID
    Unique point identification number. (Source: Processor defined)
    Range of values
    Minimum:1
    Maximum:104
    Attributes
    Type of GPS point; “check shots” refers to points along the road and prefix AP-### refers to a GPS point taken at the center of an AeroPoint with the ### referring to the last 3 digits of its identifying code. (Source: producer defined) Character string.
    Latitude NAD83[2011]
    RTK latitude (x-coordinate) of GPS position (NAD83[2011]). (Source: USGS)
    Range of values
    Minimum:41.65108346
    Maximum:41.65252053
    Units:decimal degrees
    Longitude NAD83[2011]
    RTK longitude (y-coordinate) of GPS position (NAD83[2011]). Negative values represent West coordinates. (Source: USGS)
    Range of values
    Minimum:-70.91782020
    Maximum:-70.91420483
    Units:decimal degrees
    Ellipsoid height NAD83[2011]
    Height in meters of GPS point in relation to the NAD83(2011) reference ellipsoid GRS80. (Source: USGS)
    Range of values
    Minimum:-27.607
    Maximum:-25.797
    Units:meters
    Northing 19N
    Y-coordinate of GPS point in NAD83(2011)/UTM Zone 19N. (Source: USGS)
    Range of values
    Minimum:4612812.082
    Maximum:4612971.575
    Units:meters
    Easting 19N
    X-coordinate of GPS point in NAD83(2011)/UTM Zone 19N. (Source: USGS)
    Range of values
    Minimum:340303.666
    Maximum:340606.190
    Units:meters
    Orthometric height NAVD88
    Z-coordinate of GPS point in relation to NAVD88 with GEOID 18 applied. (Source: USGS)
    Range of values
    Minimum:1.556
    Maximum:3.370
    Units:meters
    Tilt angle
    Angle of GPS pole from nadir (Source: producer defined)
    Range of values
    Minimum:0.5
    Maximum:15.2
    Units:degrees
    Elevation RMS
    Root mean square internal precision value in the z-direction. (Source: producer defined)
    Range of values
    Minimum:0.017
    Maximum:0.045
    Units:meters
    Lateral RMS
    Root mean square internal precision value in the x and y-direction. (Source: producer defined)
    Range of values
    Minimum:0.017
    Maximum:4.041
    Units:meters
    2025009FA_MI_Mar_YSMP_LPC_classified.laz
    UAS lidar point cloud in .LAZ file format. This georeferenced point cloud was colorized using natural color RGB image values and is classified with ground and unclassified points. Total point count is 34,653,696 point density is 451.61 points per square meter, and point spacing is 0.047 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:-0.783
    Maximum:41.912
    Units:meters
    Classification
    Each lidar point has a classification value assigned to it according to the ASPRS LAS Specification. (Source: Global Mapper)
    ValueDefinition
    0 (Created, never classified)Data have been subjected to a classification algorithm but emerged in an undefined state.
    2 (Ground)Data have been subjected to a classification algorithm and identified as bare ground.
    7 (Low Point)Data have been subjected to a classification algorithm and identified as low point noise.
    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:65025
    Return number
    Return number. Each laser pulse can produce multiple discrete observations as emitted light is reflected by objects in the scene. (Source: YellowScan CloudStation)
    Range of values
    Minimum:1
    Maximum:3
    Scan angle
    The scan angle of the laser beam that produced each point where 0 degrees indicates nadir. (Source: YellowScan CloudStation)
    Range of values
    Minimum:-45
    Maximum:51
    Units:Degrees
    2025009FA_MI_Mar_YSMP_DSM_10cm.tif
    A cloud-optimized digital surface model raster created from the lidar point cloud with encoded elevation values. Pixel resolution is 10 cm. (Source: USGS)
    Band_1
    Surface elevation using orthometric height NAVD88 (m) and Geoid 2018 in NAD83(2011) UTM Zone 19N. No-data value is –3.4028e+38. (Source: producer defined)
    Range of values
    Minimum:-0.783
    Maximum:27.890
    Units:meters
    2025009FA_MI_Mar_YSMP_DTM_10cm.tif
    A cloud-optimized digital terrain model raster created from the ground points of the classified lidar point cloud with encoded elevation values. (Source: USGS)
    Band_1
    Surface elevation using orthometric height NAVD88 (m) and Geoid 2018 in NAD83(2011) UTM Zone 19N. Pixel resolution is 10 cm. No-data value is –3.4028e+38. (Source: producer defined)
    Range of values
    Minimum:-0.783
    Maximum:7.060
    Units:meters
    2025009FA_MI_Mar_YSMP_SfM_Ortho_5cm.tif
    True-color (RGB) orthomosaic of Marsh Island created using structure from motion. (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 "2025009FA_MI_Mar_sensor/product_resolution.*** ", where 2025009 is the USGS Field activity ID, location is Marsh Island (MI), Mar is the month March, sensors are YellowScan Mapper Plus (YSMP), AeroPoints, and Emlid RS3; and products include orthomosaic (Ortho), digital surface and terrain models (DSM and DTM), GPS checkpoints, a list of the all the images, and lidar point cloud (LPC). Product resolution is in cm if applicable. The horizontal coordinate reference system for all products is NAD83(2011)/UTM19N, the vertical coordinate reference system is NAVD88. *** is the file extension.
    Entity_and_Attribute_Detail_Citation: USGS Field Activity 2025-009-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
    • Amit Millo
  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 x2310 (voice)
    jover@usgs.gov

Why was the data set created?

The elevation and imagery products were produced to help the site’s conservation partnership evaluate the baseline conditions of the site, with future data collections planned to monitor landscape change from remediation efforts and potential storm impacts.

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: 11-Mar-2025 (process 1 of 6)
    GROUND CONTROL: Ten AeroPoint GCPs, occasionally on top of larger black and white reflective tarps, were spaced out over the field site and left on for at least one hour to collect Global Navigation Satellite System (GNSS) data. After collection and connected to Wifi, the AeroPoint data were uploaded and run through a post-processing kinematic algorithm of the Propeller network to get a global accuracy. Internal accuracy is reported in xyz variance and with a baseline distance. The data were exported in the horizontal datum NAD83(2011) to produce latitude, longitude, and ellipsoid heights, and then UTM19N and vertical datum NAVD88 using GEOID 18 was used to produce easting and northing and orthometric heights. These were exported to a CSV file and named 2025009FA_MI_Mar_AeroPoints.csv.
    Date: 11-Mar-2025 (process 2 of 6)
    UAS FLIGHTS: The lidar sensor is 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 non-repetitive scan pattern, which moves the sensor in spirograph (flower) motion and is optimal for vegetated areas as it can capture more angles by surveying in front and behind the sensor. The camera module is 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 is saved to a 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 are saved to a micro SD card as *.JPG files. A configuration text file (CONFIG.TXT) is 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 was collected with the UAS flying at 7 m/s at 68 meters above ground level with cross grid transect passes. The camera module was set to take images every 2 seconds after reaching 60 meters altitude. After the 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 IMU/GPS data were collected. The positions have been converted in Metashape Pro to NAD83(2011) and UTM19N and NAVD88 GEOID 18 and provided in the imagery locations file (2025009FA_MI_Mar_YSMP_ImageLocations.csv).
    Date: 14-Nov-2025 (process 3 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 Emlid RS2+ 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 and calibrated on 2023-09-26 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 xyz arm offsets (0.000, -0.118, -0.490) and boresight angle corrections were applied to the LPC, along with a strip adjustment between transect swaths using CloudStation's "robust" setting. The LPC was colored by the YSMP camera based on the photo timestamp. The “Cut Overlap” function was run. The LPC was classified using CloudStation Terrain settings; Object Inner Size “10 m”; steepness “0.05”; minimal object height “0.25 m”; and point cloud thickness “0.1 m”. The LPC was exported as a zipped laz file (ver. 1.4) and opened in Global Mapper (ver. 26.0) where points were cleaned and shifted vertically with a best fit plane to fit the GCPs (2025009FA_MI_Mar_YSMP_LPC_classified.laz). The DSM was exported using maximum values of all LPC points and the Grid “No data” Distance Criteria set to 30 to fill small gaps (2025009FA_MI_Mar_YSMP_DSM_10cm.tif) and a DTM was exported using the average values of just the LPC points classified as ground and the Grid “No data” Distance Criteria set to 50 to fill small gaps (2025009FA_MI_Mar_YSMP_DSM_10cm.tif). All files were exported in EPSG:6348 (NAD83(2011)/UTM zone 19N and the vertical datum in EPSG:5703 (NAVD88 height in meters).
    Date: 12-Mar-2025 (process 4 of 6)
    RAW IMAGERY: The YSMP images were geotagged in Emlid Studio using the lidar *.T04 file and Emlid RS2+ base RINEX files from the time the UAS was in the air. The YSMP images were processed to add additional information required by the USGS to the EXIF headers using ExifTool (https://exiftool.org/, version: 12.06), and the files were renamed to a unique identifier using Namexif (http://www.digicamsoft.com/softnamexif.html, version 2.2) to avoid any possibility of duplicate names. These steps are described here. 1. ExifTool 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 '2025009FA_f01YSMP_20250311T174254Z_DSC####', 2025009FA is the field activity ID, f01 is the flight number, YSMP is the camera on the YellowScan Mapper Plus, 20250311 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.
    Date: 13-Mar-2025 (process 5 of 6)
    PHOTOGRAMMETRY: The ortho product was created in Agisoft Metashape v. 2.2.0 using the following general steps (see Over and others, 2021 for a more detailed SfM methodology explanation): 1. A project was created in Metashape and imagery was imported. 2. Photos were aligned at a low accuracy and then GCPs were automatically detected in the point cloud. AeroPoint positions (2025009FA_MI_Mar_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 0.01/0.02 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, which created a sparse point cloud and put the imagery into a relative spatial context using the GCPs. The resultant point cloud was 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 fifteen 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. A high-quality point cloud with a low-frequency filtering algorithm was made from the filtered sparse point cloud. 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. An interpolated elevation model is built from the dense point cloud and then an orthomosaic is built from the DSM with refined seamlines. The YSMP orthomosaic is a 3-band RGB-averaged orthomosaic exported at 5 cm resolution (2025009FA_MI_Mar_SfM_Ortho_5cm.tif).
    Date: 16-Jan-2026 (process 6 of 6)
    CLOUD OPTIMIZATION: The DSM and DTM 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. The orthomosaic was JPEG compressed using the command: for %i in (.\*.tif) do gdal_translate %i .\%~ni_cog.tif -of COG -stats -co BLOCKSIZE=256 -co COMPRESS=JPEG -co QUALITY=90 -co PREDICTOR=YES -co NUM_THREADS=ALL_CPUS -co BIGTIFF=YES 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 x2310 (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?
    GPS: The theoretical internal accuracy of the Emlid RS3 survey equipment is 2 cm. GPS check points with the RS3 that had a FIX were assumed to be within that tolerance after staking out at known reference mark BBNEP-2023-1 and the values were within 2 cm. The internal precision vertical and horizontal root mean square values (RMS) for each point were also reported in 2025009FA_MI_Mar_GPS_Emlid_RS3_checkpoints.csv. The ground control points (GCPs) used were Propeller AeroPoint 2s, which are an upgrade from the original AeroPoint 1s, but are referred from here on as AeroPoints. The AeroPoint GCPs have an internal reported variance provided in 2025009FA_MI_Mar_AeroPoints.csv, the global accuracy was calculated and reported below by adding the variance to twice the longest baseline distance.
    Images: The YSMP images are all geotagged with position information and various sensor data using Post Processing Kinematic (PPK) data from the base station and the YellowScan Mapper Plus (YSMP).
    GeoTIFFs: The horizontal and vertical accuracy of the products (2025009FA_MI_Mar_YSMP_DSM_10cm.tif, 2025009FA_MI_Mar_YSMP_DTM_10cm.tif, 2025009FA_MI_Mar_YSMP_SfM_Ortho_5cm.tif) were assessed using the AeroPoints and GPS Emlid check shots. It should also be noted that accuracy estimates of the products were for areas of bare ground or low vegetation where GCPs were placed or where the check shot was appropriate for the product. For example, a check shot on the bridge was not used to assess the digital terrain model (DTM) as the bridge was removed as a surface artifact but would be used to assess the digital surface model (DSM), which includes it. Additional sources of error, such as moving objects, may cause accuracy estimates to exceed estimates in localized portions of the products. Lidar data does not penetrate water. The DTM was also compared to previous data surveys at Marsh Island.
    Lidar: The point cloud (2025009FA_MI_Mar_YSMP_LPC_classified.laz) positional accuracy was based on the GPS/IMU and post positional corrections from the base station. The colorization of the points was based on the closest image and may be off by up to 30 cm. Some misalignment in the collected lidar strips on the distal ends of the collection may occur. Users are advised to evaluate the data for their own needs. The accuracy of the LPC ground classification that produced the DTM was not assessed, users are advised to do their own quality control or reclassification. Misclassification of points may have caused inaccuracies in the DTM.
  2. How accurate are the geographic locations?
    Images: The YSMP images were geotagged with the post-processed lidar *.T04 file and Emlid RS2+ base station data and had an average horizontal accuracy of 0.05 m.
    GPS: Emlid RS3 GPS RTK points have an average internal precision RMS of 2.2 cm. AeroPoint average horizontal global accuracy is 5.2 cm.
    Lidar: The horizontal accuracy of the lidar point cloud, and by association the DSM, was assessed against positions of the AeroPoints on reflective tarps (n=5) in the intensity view of the LPC. The horizontal accuracy is variable and within 30 cm.
    SfM: The orthomosaic was spatially georeferenced using the visible AeroPoint2 GCPs (n=9) and created using SfM. The horizontal root mean square error (RMSE) of the check points as reported from the Metashape project were x/y 0.02/0.03 m.
  3. How accurate are the heights or depths?
    Images: The YSMP images were geotagged with the post-processed lidar *.T04 file and base station data and had an average z accuracy of 0.05 m.
    GPS: Emlid RS3 GPS RTK points have an average internal vertical precision of 2.7 cm. AeroPoint global vertical accuracy is 7 cm.
    Lidar and products: The LPC returns within 5 cm of the GCPs were compared, and the RMSE (n=92) was 0.031 m. The lidar DSM vertical RMSE (n=95) was 0.031 m and the lidar DTM vertical RMSE (n=100) was 0.032 m. When compared to the August 2024 survey (see larger work citation), 90% of the DTM surface was within 3 to 15 cm.
  4. Where are the gaps in the data? What is missing?
    Imagery: The YSMP camera triggered every 2 seconds once it reached 60 meters altitude. Images at take-off and landing were removed. A total of 262 YSMP images are on the IDS and were used in structure from motion (SfM) processing. Products: The LPC has been classified into “ground (2)” and “created, never classified (0)” and cleaned in Global Mapper to remove water points and reclassify points near the bridge. GeoTIFF products are cloud-optimized and compressed. The DTM and DSM are partially interpolated to fill gaps in the lidar made by water or tree cover. There are 104 real time kinematic (RTK) check shots and 10 AeroPoint data points.
  5. How consistent are the relationships among the observations, including topology?
    There was one M600 UAS flight and ten AeroPoint 2 GCPs placed. One AeroPoint was obscured from view (AP-67B). The flight (14 min) used the YellowScan Mapper+ (YSMP) to collect lidar data and RGB images. These data produced the LPC, DTM, DSM, and the true-color orthomosaic (SfM_Ortho). All data fall into expected elevation ranges of a low-lying coastal marsh.

How can someone get a copy of the data set?

Are there legal restrictions on access or use of the data?
Access_Constraints No access constraints. Please see 'Distribution Information' for details.
Use_Constraints These data are marked with a Creative Commons CC0 1.0 Universal License. These data are in the public domain and do not have any use constraints. Users are advised to read the dataset's metadata thoroughly to understand appropriate use and data limitations. 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 Marsh Island includes the YellowScan Mapper Plus lidar point cloud, elevation models, imagery and image list, true-color orthomosaic, GPS check shots, and AeroPoint ground control 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: 11-May-2026
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_P19TLXVG/2025009FA_MI_Mar_metadata.faq.html>
Generated by mp version 2.9.51 on Mon May 11 14:01:11 2026