Lidar point clouds (LPC), elevation models, GPS data, image mosaics, and aerial images from natural color (RGB) camera collected during UAS operations at Lower Darby Creek, Darby Township, Pennsylvania, March 2025

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Frequently anticipated questions:

What does this data set describe?

Title:
Lidar point clouds (LPC), elevation models, GPS data, image mosaics, and aerial images from natural color (RGB) camera collected during UAS operations at Lower Darby Creek, Darby Township, Pennsylvania, March 2025
Abstract:
The U.S. Geological Survey deployed small uncrewed aircraft systems (sUAS) to collect aerial remote sensing data across sites within the Lower Darby Creek Superfund Site ~5 miles outside of Philadelphia, PA in March and August of 2025. March datasets include aerial images from natural color (RGB) and raw lidar of the Clearview Landfill superfund site. August datasets include aerial images from natural color (RGB), multispectral sensors, and raw lidar over the Clearview Landfill. These datasets were processed to produce high resolution digital elevation models (DEM), image mosaics, and lidar point clouds (LPC). Black and white cross-coded ground control points (GCPs) were surveyed using Real Time Kinematic (RTK) GPS and RTK-GPS enabled AeroPoints to georeference the model and orthomosaics during post-processing. The elevation and imagery products were produced to help partners at the Environmental Protection Agency (EPA) acquire accurate elevation data for target monitoring sites during the winter "leaf-off" period (March) and the peak growing season (August). Future data collections are planned to support long-term monitoring of landscape change resulting from remediation efforts and potential storm impacts.
Supplemental_Information:
These data were collected by the USGS Coastal and Marine Hazards and Resources Program under USGS field activity number 2025-011-FA. The field activity webpage (https://cmgds.marine.usgs.gov/services/activity.php?fan=2025-011-FA) contains additional information regarding the field activity.
  1. How might this data set be cited?
    Millo, Amit, Brosnahan, Sandra M., Ackerman, Seth D., Over, Jin-Si R., and Cramer, Jennifer M., 20260602, Lidar point clouds (LPC), elevation models, GPS data, image mosaics, and aerial images from natural color (RGB) camera collected during UAS operations at Lower Darby Creek, Darby Township, Pennsylvania, March 2025: data release DOI:10.5066/P13TQ8E7, 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.

    Millo, Amit, Brosnahan, Sandra M., Ackerman, Seth D., Over, Jin-Si R., and Cramer, Jennifer M., 2026, Topographic data, aerial imagery, and GPS data collected during uncrewed aircraft system (UAS) operations at Lower Darby Creek, Darby Township, Pennsylvania, March to August 2025: data release DOI:10.5066/P13TQ8E7, U.S. Geological Survey, Reston, VA.

    Online Links:

    Other_Citation_Details:
    Millo, A., Brosnahan, S.M., Ackerman, S.D., Over, J.R., and Cramer, J.M., 2026, Topographic data, aerial imagery, and GPS data collected during uncrewed aircraft system (UAS) operations at Lower Darby Creek, Darby Township, Pennsylvania, March to August 2025: U.S. Geological Survey data release, https://doi.org/10.5066/P13TQ8E7
  2. What geographic area does the data set cover?
    West_Bounding_Coordinate: -75.258575
    East_Bounding_Coordinate: -75.247749
    North_Bounding_Coordinate: 39.908567
    South_Bounding_Coordinate: 39.897749
  3. What does it look like?
    https://www.sciencebase.gov/catalog/file/get/69839c8ab66b01367d7ecd96?name=2025MarchDarbyChildPage.jpg&allowOpen=true (JPEG)
    Sample of data collected during March 2025 field session.
  4. Does the data set describe conditions during a particular time period?
    Beginning_Date: 26-Mar-2025
    Ending_Date: 27-Mar-2025
    Currentness_Reference:
    Ground condition
  5. What is the general form of this data set?
    Geospatial_Data_Presentation_Form: digital image, 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: 18
      Transverse_Mercator:
      Scale_Factor_at_Central_Meridian: 0.999600
      Longitude_of_Central_Meridian: -75.000000
      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?
    2025011FA_Clearview_Mar_ImageryLocations.csv
    The CSV file contains the approximate position of the W1G2 MAP61 images at the moment of each capture based on post-processed UAS integrated GPS. (Source: Producer defined)
    ImageName
    File names of individual images, see the Process Description for file naming convention. (Source: Producer defined) Character string.
    GPSDateTime
    Date and time of each image in the format YYYY:MM:DD HH:MM:SSZ where YYYY is the four-digit year, MM the two-digit month, DD the two-digit day, HH the two-digit the hour, MM the two-digit the minute, SS the two-digit seconds, and a Z follows at the end to represent Zulu time. (Source: USGS) Character string.
    Latitude [EPSG:6319]
    Latitude (y) in WGS84 of camera based on time of each image capture. Positive values represent north coordinates. (Source: USGS)
    Range of values
    Minimum:39.89907309
    Maximum:39.90685538
    Units:decimal degrees
    Longitude [EPSG:6319]
    Longitude (x) in WGS84 of camera based on time of each image capture. Negative values represent west coordinates. (Source: USGS)
    Range of values
    Minimum:-75.25760886
    Maximum:-75.25060402
    Units:decimal degrees
    Ellipsoid height (m) [GRS 1980]
    Ellipsoid elevation (in meters) of the camera at time of each image capture. (Source: USGS)
    Range of values
    Minimum:23.0889
    Maximum:50.3828
    Units:meters
    Easting (m) [EPSG:6347]
    Easting coordinate in NAD83(2011) / UTM zone 18N of the image in meters. (Source: USGS)
    Range of values
    Minimum:477979.2122
    Maximum:478578.7791
    Units:meters
    Northing (m) [EPSG:6347]
    Northing coordinate in NAD83(2011) / UTM zone 18N of the image in meters. (Source: USGS)
    Range of values
    Minimum:4416586.455
    Maximum:4417449.782
    Units:meters
    Orthometric height (m) [NAVD88, GEOID18]
    Orthometric elevation in meters of the camera at time of each image capture. (Source: USGS)
    Range of values
    Minimum:56.05153738
    Maximum:83.34749193
    Units:meters
    2025011FA_Clearview_Mar_GCP.csv
    Comma Separated Value (CSV) file containing GNSS related data generated by the AeroPoint2s. (Source: Producer Defined)
    FAN
    USGS Field Activity Number (Source: USGS)
    ValueDefinition
    2025-011-FAYear, USGS ID, and Field Activity
    Date
    Date of each image in the format YYYYMMDD where YYYY is the four-digit year, MM the two-digit month, DD the two-digit day. (Source: USGS)
    Range of values
    Minimum:20250326
    Maximum:20250327
    Point ID
    Abbreviated reference for each Aeropoint2 datapoint used in this field session. A points were collected day one and B points day 2. The number following the letter is unique per day. (Source: Processor defined) Character string.
    Aeropoint ID
    Unique identifier for each ground control point. (Source: Processor defined) Character string.
    Easting (m) [EPSG:6347]
    Post-processed X-coordinate of AeroPoint2 in NAD83(2011)/UTM Zone 18N (Source: USGS)
    Range of values
    Minimum:478020.567
    Maximum:478459.492
    Units:meters
    Northing (m) [EPSG:6347]
    Post-processed Y-coordinate of AeroPoint2 in NAD83(2011)/UTM Zone 18N. (Source: USGS)
    Range of values
    Minimum:4416640.164
    Maximum:4417373.679
    Units:meters
    Orthometric height (m) [NAVD88, GEOID18]
    Post-processed Z-coordinate of AeroPoint2 using NAVD88 with GEOID 18 applied. (Source: USGS)
    Range of values
    Minimum:3.486
    Maximum:31.823
    Units:meters
    Latitude [EPSG:6319]
    Post-processed latitude of AeroPoint2 position in NAD83(2011). (Source: USGS)
    Range of values
    Minimum:39.89955692
    Maximum:39.90616973
    Units:decimal degrees
    Longitude [EPSG:6319]
    Post-processed longitude of AeroPoint2 position in NAD83(2011). (Source: Producer Defined)
    Range of values
    Minimum:-75.25712572
    Maximum:-75.2519984
    Units:decimal degrees
    Ellipsoid height (m) [GRS 1980]
    Post-processed height in meters of AeroPoint2 in relation to the NAD83(2011) reference ellipsoid GRS80. (Source: USGS)
    Range of values
    Minimum:-29.478
    Maximum:-1.143
    Units:meters
    X variance (mm)
    Variance in the X-coordinate from post-processing (Source: Producer Defined)
    Range of values
    Minimum:1.9
    Maximum:8.4
    Units:millimeters
    Y variance (mm)
    Variance in the Y-coordinate from post-processing (Source: Producer Defined)
    Range of values
    Minimum:2.7
    Maximum:8.0
    Units:millimeters
    Z variance (mm)
    Variance in the Z-coordinate from post-processing (Source: Producer Defined)
    Range of values
    Minimum:3.2
    Maximum:18.2
    Units:millimeters
    Baseline distance (km)
    Distance of AeroPoint2 from nearest used processing network base station (Source: Producer Defined)
    Range of values
    Minimum:0.09
    Maximum:13.89
    Units:kilometers
    2025011FA_Clearview_Mar_Emlid_RTK.csv
    Comma Separated Value (CSV) file containing data collected by the Emlid Rover. (Source: Producer Defined)
    FAN
    USGS Field Activity Number (Source: USGS)
    ValueDefinition
    2025-011-FAYear, USGS ID, and Field Activity
    Date
    Date of each image in the format YYYYMMDD where YYYY is the four-digit year, MM the two-digit month, DD the two-digit day. (Source: USGS)
    Range of values
    Minimum:20250306
    Maximum:20250306
    Name
    Abbreviated reference for each Aeropoint2 datapoint used in this field session. A represents that the points were collected day one and the number following the letter is unique per check point. (Source: Producer Defined) Character string.
    Attributes
    Additional information assigned to each GPS check shot while collecting the data. "Base location" represents the entered location of the base station. "Transect" represents checkshots taken with the rover to compare the elevations of the LPC. Target represents checkshots taken over the center of an AeroPoint to validate its location. (Source: Producer Defined) Character string.
    Easting (m) [EPSG:6347]
    Post-processed X-coordinate of check point in NAD83(2011)/UTM Zone 18N (Source: USGS)
    Range of values
    Minimum:478058.978
    Maximum:478302.016
    Units:meters
    Northing (m) [EPSG:6347]
    Post-processed Y-coordinate of check point in NAD83(2011)/UTM Zone 18N (Source: USGS)
    Range of values
    Minimum:4416843.173
    Maximum:4417122.027
    Units:meters
    Orthometric height (m) [NAVD88, GEOID18]
    Post-processed Z-coordinate of check shot using NAVD88 with GEOID 18 applied. (Source: USGS)
    Range of values
    Minimum:9.666
    Maximum:31.796
    Units:meters
    Latitude [EPSG:6319]
    Post-processed latitude of check point position in NAD83(2011). (Source: USGS)
    Range of values
    Minimum:-75.25667668
    Maximum:-75.25383907
    Units:decimal degrees
    Longitude [EPSG:6319]
    Post-processed longitude of check point position in NAD83(2011). (Source: USGS)
    Range of values
    Minimum:39.901383
    Maximum:39.90390042
    Units:decimal degrees
    Ellipsoid height (m) [GRS 1980]
    Post-processed height in meters of check point in relation to the NAD83(2011) reference ellipsoid GRS80. (Source: USGS)
    Range of values
    Minimum:-23.299
    Maximum:-1.169
    Units:meter
    Tilt angle (deg)
    Angle to nadir of the Emlid RS3 (Source: Producer Defined)
    ValueDefinition
    NANo Data
    Range of values
    Minimum:0.3
    Maximum:5.3
    Units:degrees
    Elevation RMS (m)
    Root mean square in the Z-coordinate (Source: Producer Defined)
    ValueDefinition
    NANo Data
    Range of values
    Minimum:0.011
    Maximum:0.013
    Units:meters
    Lateral RMS (m)
    Root mean square in the horizontal XY-coordinate (Source: Producer Defined)
    ValueDefinition
    NANo Data
    Range of values
    Minimum:0.017
    Maximum:0.019
    Units:meters
    Baseline (m)
    Straight line distance of check point from base station in meters. (Source: Producer Defined)
    ValueDefinition
    NANo Data
    Range of values
    Minimum:18.61
    Maximum:340.305
    Units:meters
    2025011FA_Clearview_Mar_WLDR_LPC.laz
    UAS lidar point cloud in *.laz v. 1.4 file format. This georeferenced point cloud was colorized using natural color RGB image values and is not classified. There are 86,181,891 points. Point density is 224.54 points per square meter and point spacing is 0.0667 m. (Source: Wingtra)
    Elevation
    Surface elevation orthometric height NAVD88 (m) using Geoid 18 in NAD83(2011)/UTM Zone 18N. (Source: Wingtra)
    Range of values
    Minimum:0.271
    Maximum:34.829
    Units:meters
    Return Number
    The sequence index of a lidar return within a single emitted pulse, indicating the order in which reflections were received. (Source: Wingtra)
    Range of values
    Minimum:1
    Maximum:3
    Intensity
    The return strength of a laser beam during data collection. (Source: Wingtra)
    Range of values
    Minimum:0
    Maximum:255
    Class Code
    The LPC is unclassified so the class code is 1 for all points. (Source: Wingtra)
    Range of values
    Minimum:1
    Maximum:1
    Scan Angle
    The angle at which a laser pulse is emitted from a scanner, measured relative to a nadir position. (Source: Wingtra)
    Range of values
    Minimum:-43
    Maximum:45
    Point Source
    Point source is the origin of each lidar return, representing the specific sensor emission event from which the point was derived. (Source: Wingtra)
    Range of values
    Minimum:0
    Maximum:31
    2025011FA_Clearview_Mar_MAP61_Ortho_5cm.tif
    Cloud-optimized JPEG compressed true-color orthomosaic. (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
    2025011FA_Clearview_Mar2024_WLDR_DSM_10cm.tif
    A cloud-optimized digital surface model gridded using the Minimum Binning (DSM) method in Global Mapper from the "2025011FA_Clearview_Mar_WLDR_LPC" lidar point cloud with encoded elevation values. Pixel resolution is 10 cm. (Source: USGS)
    Value
    Surface elevation orthometric height NAVD88 (m) using Geoid 2018 in NAD83(2011) UTM Zone 18N. (Source: producer defined)
    Range of values
    Minimum:0.271
    Maximum:34.829
    Units:meters
    2025011FA_Clearview_Mar2024_WLDR_DTM_10cm.tif
    A cloud-optimized digital terrain model gridded using the Triangulated Irregular Network (TIN) method in Global Mapper from the "2025011FA_Clearview_Mar_WLDR_LPC" lidar point cloud with encoded elevation values. Pixel resolution is 10 cm. (Source: USGS)
    Value
    Surface elevation orthometric height NAVD88 (m) using Geoid 2018 in NAD83(2011) UTM Zone 18N. (Source: producer defined)
    Range of values
    Minimum:0.7773
    Maximum:31.9003
    Units:meters
    Entity_and_Attribute_Overview:
    The filenames are formatted as "2025011FA_Clearview_Mar_Sensor_Product_Resolution.*", where 2025011 is the USGS Field activity ID, Clearview is the location, and Mar is the data collection month; sensor includes the Wingtra MAP61 (MAP61), Wingtra Lidar (WLDR), Emlid RS3 (Emlid), and AeroPoint2s (GCP); products include orthomosaic (Ortho), digital surface model (DSM), digital terrain model (DTM) and lidar point cloud (LPC). The horizontal coordinate reference system for all products is NAD83(2011)/UTM18N, the vertical coordinate reference system is NAVD88 using GEOID 18. Image location coordinate reference systems are specific to the sensor and can be viewed in the image locations CSV files.
    Entity_and_Attribute_Detail_Citation:
    The entity and attribute information were generated by the data release first author, unless otherwise noted. Please review the rest of the metadata record for additional details and information.

Who produced the data set?

  1. Who are the originators of the data set? (may include formal authors, digital compilers, and editors)
    • Amit Millo
    • Sandra M. Brosnahan
    • Seth D. Ackerman
    • 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?
    Amit Millo
    U.S. Geological Survey, Northeast Region, Woods Hole Coastal and Marine Science Center
    Geologist
    384 Woods Hole Rd.
    Woods Hole, MA

    508-548-8700 x2223 (voice)
    amillo@usgs.gov

Why was the data set created?

Lidar data were collected to penetrate vegetation canopy and provide accurate digital terrain models (DTMs) during the winter "leaf-off" period. Aerial imagery was collected with appropriate resolution and overlap to permit high-quality photogrammetry and generation of digital surface models (DSM) and orthoimagery.

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: 27-Mar-2025 (process 1 of 5)
    GROUND CONTROL: Over the two days of data collection, 20 AeroPoint2 GCPs were spaced out over the field site and left on for at least 30 minutes to collect GNSS data. One Aeropint failed on day one so only 19 are recorded. After collection the AeroPoint2s data were uploaded via a Wi-Fi connection and run through a post-processing kinematic algorithm of the Propeller network to get corrected positions. The data were exported in NAD83(2011) (EPSG:6318) to produce latitude, longitude, and ellipsoid heights, and then NAD83(2011)/UTM zone 18N (EPSG:6347) and NAVD88 (EPSP:5703) with GEOID 18 to produce easting and northing and orthometric heights. These were exported to a CSV file and named 2025011FA_Clearview_Mar_GCP.csv. An Emlid RS2+ was set up as a base station using an RTK FIX on the highest section of boardwalk to record GNSS data for post processing the lidar data. An Emlid RS3 with tilt compensation was connected to the base to take RTK three-second averaged check shots the parking lot, beach, and AeroPoint2s, data were provided in 2025011FA_Clearview_Mar_Emlid_RTK.csv
    UAS FLIGHTS: The lidar sensor was a 905 nm wavelength Hesai XT32-M2X with a 90 / 40.3 degree horizontal and vertical field of view (FOV). It is a rotating sensor, generating up to three returns with an effective point rate for a single return of 160k pts/s. The camera module uses the Wingtra MAP61 61-megapixel (MP) camera with a 17 mm lens. The system uses a NovAtel OEM7500 multi-frequency, high precision GNSS receiver. The lidar data was saved to the 256 GB thumb drive in eight different *.data files. The RGB images are saved as *.JPG files. The lidar data were collected with the Wingtra UAS flying 61 meters above ground level with northeast-southwest transect passes. The camera module was set to take images based on GNSS coordinates calculated by Wingtra based on the flight area. After the flights the lidar and RGB data were taken off their respective sensor. Note, the geotagged positions embedded in the imagery Exif information were in EPSG:4326, this is the only option in the software. The positions were converted to EPSG:6347 and EPSG:5703 in the imagery locations file (2025011FA_Clearview_Mar_ImageryLocations.csv) and were accounted for when transforming to EPSG:6347 and EPSG:5703 in the products.
    Date: 10-Jul-2025 (process 2 of 5)
    RAW IMAGERY: The W1G2 images were geotagged in WingtraHub using the base station RINEX file and OPUS corrected location of the base. All 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 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 using a Python script 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 '2025011FA_f13MAP61_20250327T164058Z_#####', 2025011FA is the field activity ID; f13 is the flight number for that day; MAP61 is camera used; 20250327 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 ##### is the original raw photo suffix appended to the end of the new filename. 3. Images are validated and uploaded onto the Imagery Data System.
    Date: 16-Jul-2025 (process 3 of 5)
    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 and imagery was imported along with a csv file containing the following information about the camera when the image was taken: latitude/longitude (WGS84), ellipsoid altitude (m), vertical and horizontal accuracy (m), omega/phi/kappa (°), and accuracy (°). 2. Photos were aligned at a high accuracy 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 PPK geotagged image locations. 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 10, and multiple 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. In a new chunk a high-quality dense cloud with a low-frequency filtering algorithm was made. The dense point cloud was then edited by visual inspection to remove points with a low confidence near the edges and near water bodies. 5. An interpolated DSM was built from the dense point cloud and then an orthomosaic was built from the DSM with refined seamlines. This DSM was then used to generate the orthomosiac, which consists of 3-bands and was exported at 5 cm resolution (2025011FA_Clearview_Mar_MAP61_Ortho_5cm.tif). Step processed by J. Cramer. Person who carried out this activity:
    Jen Cramer
    U.S. Geological Survey, Woods Hole Coastal and Marine Science Center
    Geologist
    U.S. Geological Survey
    Woods Hole, MA

    508-548-8700 (voice)
    whsc_data_contact@usgs.gov
    Contact_Instructions:
    The contact email address is a generic address in the event the person is no longer working at USGS.
    Date: 16-Jul-2025 (process 4 of 5)
    LIDAR DATA: The lidar data were processed in the Wingtra LIDAR app. The .data files were uploading into the app along with the base station RINEX *.25O file. The OPUS corrected location of the base and the ARP-APC offset were then entered manually. After the processing was complete, the start and end location of each transect was manually identified to clip the paths and remove points obtained when the aircraft was turning. This point cloud product was exported from the Wingtra LIDAR app and was brought into Global Mapper (GM) and manually cleaned of points interpreted to be noise. The LPC was colorized in GM with the SfM orthomosaic. Then, the LPC was gridded at 25 cm into a DSM using maximum values binning grid method and the setting 'Grid "No Data" Distance' set to 0, along with a 10 cm DTM generated using TIN gridding; the resulting file was exported as 2025011FA_Clearview_Mar_WLDR_DSM_10cm.tif. and 2025011FA_Clearview_Mar_WLDR_DTM_10cm.tif. The LPC was exported as 2025015FA_Clearview_Mar_WLDR_LPC.laz. All files were exported in EPSG:6347 and EPSG:5703 using GEOID 18.
    Date: 16-Jul-2025 (process 5 of 5)
    CLOUD OPTIMIZATION: The DSM and DTM were deflate compressed and turned into a cloud-optimized GeoTIFF (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 and turned into a 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=JPEG -co QUALITY=90 -co PREDICTOR=YES -co NUM_THREADS=ALL_CPUS -co BIGTIFF=YES Person who carried out this activity:
    Amit Millo
    U.S. Geological Survey, Woods Hole Coastal and Marine Science Center
    Geologist
    U.S. Geological Survey
    Woods Hole, MA

    508-548-8700 x2223 (voice)
    amillo@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 is 2 cm. Points were assumed to be within that tolerance after staking out a known reference mark and the values were within 2 cm. The vertical and horizontal root mean square errors (RMS) for each point were also reported in 2025011FA_Clearview_Mar_Emlid_RTK.csv. The AeroPoint2 GCPs have an internal reported variance provided in 2025011FA_Clearview_Mar_GCP.csv. The global accuracy was calculated and reported below by adding the variance to twice the longest baseline distance. Some AeroPoint2s were also surveyed by the RS3.
    GeoTIFFs: The horizontal and vertical accuracy of the products (2025011FA_Clearview_Mar_WLDR_DSM_10cm.tif, 2025011FA_Clearview_Mar_WLDR_DTM_10cm.tif, and 2025011FA_Clearview_Mar_MAP61_Ortho_5cm.tif) were assessed using the AeroPoint2 ground control points (GCPs) and check points. 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 check points taken. Additional sources of error, such as moving objects, may cause accuracy estimates to exceed estimates in localized portions of the products.
    Lidar: The point cloud (2025015FA_Clearview_Mar_WLDR_LPC.laz) positional accuracy is based on the GPS/IMU and post positional corrections from the base station but the vertical point spread on a flat surface is about 8 cm. The LPC was colorized from the SfM orthomosaic. Some misalignment in the collected lidar strips may occur. Lidar does not pass through water. Users are advised to evaluate the data for their own needs.
  2. How accurate are the geographic locations?
    Images: The Wingtra MAP61 images were geotagged in WingtraHub v. 2.18.0 using base station data and had an average xy accuracy of 0.03 m.
    GPS: Emlid RS3 GPS points have an xy RMS (precision) average of 1.7 cm. AeroPoint2 horizontal global accuracy is 4.3 cm.
    Lidar: The lidar point cloud, and by association the DSM, horizontal accuracy was assessed against positions of the AeroPoint2s in the lidar intensity view (not the RGB). The horizontal accuracy is variable and within 10 cm.
    SfM: The orthomosaic was created using SfM and georeferenced as a result of using Post-Processed Kinematic (PPK) geotagged aerial images (done so in WingtraHub). The horizontal average camera location errors as reported from the Metashape projects were x/y 0.033/0.038 m.
  3. How accurate are the heights or depths?
    Images: The MAP61 images were geotagged in WingtraHub v. 2.18.0 using the base station data and had an average x/y accuracy of 0.02m and z accuracy of 0.03 m. GPS: Emlid RS3 GPS points have a z RMSE (precision) average of 1.1 cm. AeroPoint2 global vertical accuracy is 7.0 cm.
    Lidar: The DSM was assessed against the elevations of the AeroPoint2s and RS3 check points: the RMSE (n=125) was 0.03 m.
  4. Where are the gaps in the data? What is missing?
    Imagery: The MAP61 camera triggered based on GNSS location, but roughly every 2 seconds. Images were only taken over the area of interest for a total of 458 MAP61 images. Products: GeoTIFF products are cloud-optimized and deflate compressed. The LPC has been cleaned in Global Mapper to obvious noise (like birds).
  5. How consistent are the relationships among the observations, including topology?
    There were two UAS flights and ten AeroPoint2 GCPs. Flight one (20 min) used the MAP61 camera module on the WingtraOne GEN II to collect RGB images that were used to generate the orthomosaic. Flight two (17 min) collected lidar data (WLDR) and produced the lidar point cloud (LPC), digital surface model (DSM), and digital terrain model (DTM). An Emlid RS2+ was set up as a base station and an Emlid RS3 GPS unit was used to collect check points.

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. These data are not intended to be used for navigation.
  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 The Darby Creek Superfund Site includes a lidar point cloud, two elevation models, one natural color orthomosaic, associated imagery, 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.
  4. How can I download or order the data?

Who wrote the metadata?

Dates:
Last modified: 02-Jun-2026
Metadata author:
Amit Millo
U.S. Geological Survey, Northeast Region
Geologist
U.S. Geological Survey
Woods Hole, MA

508-548-8700 x2223 (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_P13TQ8E7/2025011FA_Clearview_Mar_Metadata.faq.html>
Generated by mp version 2.9.51 on Tue Jun 2 16:04:42 2026