Orthomosaic representing Head of the Meadow Beach, Truro from images collected during field activity 2021-014-FA on February 4, 2021

Frequently anticipated questions:

• What does this data set describe?
  1. How might this data set be cited?
  2. What geographic area does the data set cover?
  3. What does it look like?
  4. Does the data set describe conditions during a particular time period?
  5. What is the general form of this data set?
  6. How does the data set represent geographic features?
  7. How does the data set describe geographic features?
• Who produced the data set?
  1. Who are the originators of the data set?
  2. Who also contributed to the data set?
  3. To whom should users address questions about the data?
• Why was the data set created?
• How was the data set created?
  1. From what previous works were the data drawn?
  2. How were the data generated, processed, and modified?
  3. What similar or related data should the user be aware of?
• How reliable are the data; what problems remain in the data set?
  1. How well have the observations been checked?
  2. How accurate are the geographic locations?
  3. How accurate are the heights or depths?
  4. Where are the gaps in the data? What is missing?
  5. How consistent are the relationships among the data, including topology?
• How can someone get a copy of the data set?
  1. Are there legal restrictions on access or use of the data?
  2. Who distributes the data?
  3. What's the catalog number I need to order this data set?
  4. What legal disclaimers am I supposed to read?
  5. How can I download or order the data?
• Who wrote the metadata?

What does this data set describe?

1. How might this data set be cited?
   U.S. Geological Survey, 20220131, Orthomosaic representing Head of the Meadow Beach, Truro from images collected during field activity 2021-014-FA on February 4, 2021: data release DOI:10.5066/P9D94NZ3, U.S. Geological Survey, Coastal and Marine Hazards and Resources Program, Woods Hole Coastal and Marine Science Center, Woods Hole, MA.

   Online Links:

   • https://doi.org/10.5066/P9D94NZ3
   • https://cmgds.marine.usgs.gov/data/field-activity-data/2021-014-FA/

   This is part of the following larger work.
   Over, J., Sherwood, C., and Traykovski, P., 2022, Topographic and bathymetric data, structure from motion imagery, and ground control data collected at Head of the Meadow, Truro in February 2021, U.S. Geological Survey Field Activity 2021-014-FA: data release DOI:10.5066/P9D94NZ3, U.S. Geological Survey, Reston, VA.

   Online Links:

   • https://doi.org/10.5066/P9D94NZ3

   Other_Citation_Details:

   Over, J.R., Sherwood, C.R., and Traykovski, P.A., 2022, Topographic and bathymetric data, structure from motion imagery, and ground control data collected at Head of the Meadow, Truro in February 2021, U.S. Geological Survey Field Activity 2021-014-FA: U.S. Geological Survey data release, https://doi.org/10.5066/P9D94NZ3

2. What geographic area does the data set cover?

   West_Bounding_Coordinate: -70.08075650
   East_Bounding_Coordinate: -70.07445348
   North_Bounding_Coordinate: 42.05300655
   South_Bounding_Coordinate: 42.04960704
   

3. What does it look like?

   https://cmgds.marine.usgs.gov/data/field-activity-data/2021-014-FA/data/Imagery/2021014FA_Truro_ortho_browse.JPG (JPEG)

   True-Color RBG image of Head of the Meadow Beach, Truro MA

4. Does the data set describe conditions during a particular time period?

   Calendar_Date: 04-Feb-2021

   Currentness_Reference:

   ground condition; single survey day: ground control points were collected on February 4, 2021.

5. What is the general form of this data set?

   Geospatial_Data_Presentation_Form: raster digital data
   

6. How does the data set represent geographic features?
   1. How are geographic features stored in the data set?
      This is a Raster data set. It contains the following raster data types:
      • Dimensions 3710 x 5170, type Pixel
   2. What coordinate system is used to represent geographic features?
      

      Grid_Coordinate_System_Name: Universal Transverse Mercator
      Universal_Transverse_Mercator:

      UTM_Zone_Number: 19
      Transverse_Mercator:

      Scale_Factor_at_Central_Meridian: 0.999600
      Longitude_of_Central_Meridian: -69.000000
      Latitude_of_Projection_Origin: 0.000000
      False_Easting: 500000.000000
      False_Northing: 0.000000
      

      Planar coordinates are encoded using row and column
      Abscissae (x-coordinates) are specified to the nearest 0.01
      Ordinates (y-coordinates) are specified to the nearest 0.01
      Planar coordinates are specified in meters
      The horizontal datum used is North American Datum of 1983 (National Spatial Reference System 2011).
      The ellipsoid used is GRS_1980.
      The semi-major axis of the ellipsoid used is 6378137.000000.
      The flattening of the ellipsoid used is 1/298.257222101.
      
7. How does the data set describe geographic features?

   2021014FA_Truro_ortho_10cm

   A raster dataset (unsigned 8-bit integer GeoTIFF format) with encoded RGB values of Head of the Meadow Beach in Massachusetts as recorded on February 4, 2021. Pixel resolution is 10-cm. Pixel based raster matrix with 3 layers of information for each pixel. (Source: Producer defined)

   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:

   There are no text attributes associated with a binary GeoTIFF image. The horizontal projection is in NAD83(2011). There are no 'no-data' values within the ortho.

   Entity_and_Attribute_Detail_Citation: USGS Field Activity 2021-014-FA
   

Who produced the data set?

1. Who are the originators of the data set? (may include formal authors, digital compilers, and editors)
   • U.S. Geological Survey
2. Who also contributed to the data set?
3. To whom should users address questions about the data?
   Jin-Si Over

   U.S. Geological Survey

   U.S. Geological Survey 384 Woods Hole Rd.

   Woods Hole, MA
   

   508-548-8700 x2269 (voice)

   jover@usgs.gov

Why was the data set created?

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: 25-Jun-2021 (process 1 of 2)

   The orthomosaic was created in Agisoft Metashape v. 1.7.2 using the following general steps (see Over and others, 2021 for a more detailed methodology explanation): 1. The project was created and imagery (located in larger work citation 2021014FA_Truro_f1.zip) and positions (located in larger work citation 2021014FA_Truro_f1_photolocations.csv) were imported using the NAD83(2011) datum. 2. Accuracies for the ground control points (GCPs) were set 0.05 m and accuracies for the camera positions were set to 1 m. The photos were aligned with high accuracy (the pixels are not subsampled for increased processing speed) using a keypoint limit of 50,000 and unlimited tie points. 3. Ten GCPs (2021014FA_Truro_nav_AeroPoints.csv located in the larger work citation) were added to the project in NAD83(2011) and manually placed on the images as markers. 4. The alignment process matches pixels between images to create point clouds and puts the imagery into a relative spatial context using the photo positions and GCPs. Then, Metashape software refined and optimized, using least squares, the camera positions and lens model using gradual selection and optimization parameters of: Ru = 15, Pa = 5, and Re = 0.5 to minimize the reprojection error or the distance between the measured points and the software created points. 5. A dense point cloud was generated using the high quality setting (images were not subsampled) and a low frequency filtering algorithm. The total camera position error was 5 m (XYZ: 2.16, 4.25, 0.99) and the total GCP error was 0.019 m (XYZ: 0.010, 0.010, 0.012). The dense point cloud was then edited to remove noise by filtering by point confidence before generating an interpolated digital elevation model (the software calls all models elevation models, but technically it is a surface model because it includes vegetation/canopy returns, a terrain model would be only bare earth returns). 6. The digital surface model was used to build an orthomosaic, which was then exported from the software at a resolution of 10 cm and in NAD83(2011)/UTM Zone 19N (ESPG:6348) and GEOID 18B NAVD88 in meters. Person who carried out this activity:
   

   Jin-Si Over

   U.S. Geological Survey

   Geographer

   384 Woods Hole Rd

   Woods Hole, MA
   

   508-548-8700 x2269 (voice)

   jover@usgs.gov

   Date: 11-Apr-2022 (process 2 of 2)

   Update the publication date to 'go live' date. Modified browse graphic name to be the URL to the browse graphic. This work done on 20220307. Added PID to metadata (20220411). Any edits to the metadata also include an update to the metadata date. Person who carried out this activity:
   

   U.S. Geological Survey

   Attn: VeeAnn A. Cross

   Marine Geologist

   384 Woods Hole Rd.

   Woods Hole, MA
   

   USA

   (508) 548-8700 x2251 (voice)

   (508) 457-2310 (FAX)

   vatnipp@usgs.gov

3. What similar or related data should the user be aware of?
   Over, Jin-Si R., Sherwood, Chris R., Traykovski, Peter A., Brosnahan, Sandra M., Martini, Marinna A., and Marsjanik, Eric, 2021, Topographic and bathymetric data, sediment samples, and imagery collected at Head of the Meadow Beach, Truro in March 2020, U.S. Geological Survey Field Activity 2020-015-FA: U.S. Geological Survey, Coastal and Marine Hazards and Resources Program, Woods Hole Coastal and Marine Science Center, Woods Hole, MA.

   Online Links:

   • https://doi.org/10.5066/P9KSG1RQ

   Other_Citation_Details:

   This publication is the original/first survey data of Head of the Meadow beach from 2020.

   Over, Jin-Si R., Ritchie, Andrew C., Kranenburg, Christine, Jennifer (Jenna) A. Brown, Buscombe, Daniel D., Noble, Tom, Sherwood, Christopher R., Warrick, Jonathan, and Wernette, Phillipe, 2021, Processing coastal imagery with Agisoft Metashape Professional Edition, version 1.6—Structure from motion workflow documentation: Open-File Report 2021-1039, U.S. Geological Survey, Reston, VA.

   Online Links:

   • https://doi.org/10.3133/ofr20211039

   Other_Citation_Details:

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

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

1. How well have the observations been checked?
   The positional information used on the Helikite and ground control point datasets and metadata are available in the imagery and navigational components of the larger work citation. No color corrections were applied.
2. How accurate are the geographic locations?
   Navigation information was acquired from a GNSS receiver (EMLID Reach M2) in PPK mode with a Multi-band GNSS antenna that has a theoretical horizontal accuracy of 2-5 cm. However, using these values in Metashape returned a poor product so the accuracy was loosened to 1 m to rely more on the ground control points, which have a theoretical accuracy of 1-2 cm. The final product was compared to the previous survey at Head of the Meadow (see first cross-reference) and the XY difference at a stable point was within 10 cm.
3. How accurate are the heights or depths?
   
4. Where are the gaps in the data? What is missing?
   The structure from motion process that builds the interpolated digital surface model (DSM) and orthomosaic uses all the available imagery and location information but gaps in the data may appear blurry due to interpolation. Users are advised to read the rest of the metadata record carefully for additional details.
5. How consistent are the relationships among the observations, including topology?
   There is one orthomosaic of Head of the Meadow Beach created from imagery in the larger work citation.

How can someone get a copy of the data set?

1. Who distributes the data set? (Distributor 1 of 1)
   
   Jin-Si Over

   U.S. Geological Survey

   Geographer

   U.S. Geological Survey

   Woods Hole, MA
   

   508-548-8700 x2269 (voice)

   jover@usgs.gov
2. What's the catalog number I need to order this data set? GeoTIFF file 2021014FA_Truro_ortho_10cm.tif is an unsigned 8-bit integer representing the orthomosaic image of the survey area at Head of the Meadow Beach, Truro, MA.
3. What legal disclaimers am I supposed to read?
   Neither the U.S. Government, the Department of the Interior, nor the USGS, nor any of their employees, contractors, or subcontractors, make any warranty, express or implied, nor assume any legal liability or responsibility for the accuracy, completeness, or usefulness of any information, apparatus, product, or process disclosed, nor represent that its use would not infringe on privately owned rights. The act of distribution shall not constitute any such warranty, and no responsibility is assumed by the U.S. Geological Survey in the use of these data or related materials. Any use of trade, product, or firm names is for descriptive purposes only and does not imply endorsement by the U.S. Government.
4. How can I download or order the data?
   • Availability in digital form:

     Data format:	GeoTIFF of the orthomosaic for Head of the Meadow Beach, Truro MA on February 4, 2021. in format GeoTIFF (version 1.0.0) unsigned 8-bit integer GeoTIFF Size: 33.9
     Network links:	https://cmgds.marine.usgs.gov/data/field-activity-data/2021-014-FA/data/Imagery/2021014FA_Truro_ortho_10cm.tif https://cmgds.marine.usgs.gov/data/field-activity-data/2021-014-FA/ https://doi.org/10.5066/P9D94NZ3

   • Cost to order the data: None.

Who wrote the metadata?

Dates:

Last modified: 18-Mar-2024

Metadata author:

Jin-Si Over

U.S. Geological Survey

Geographer

U.S. Geological Survey

Woods Hole, MA

508-548-8700 x2269 (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. (updated on 20240318)

Metadata standard:

Content Standard for Digital Geospatial Metadata (FGDC-STD-001-1998)