Orthomosaic representing Head of the Meadow Beach, Truro on March 10, 2022

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?
   Over, Jin-Si R., 20220919, Orthomosaic representing Head of the Meadow Beach, Truro on March 10, 2022: data release DOI:10.5066/P9GEVWG1, 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/P9GEVWG1
   • https://www.sciencebase.gov/catalog/item/62dff9eed34e952be90980ea

   This is part of the following larger work.
   Over, Jin-Si R., Sherwood, Christopher R., and Traykovski, Peter A., 2022, Topographic and bathymetric data, structure from motion imagery, and ground control data collected at Head of the Meadow Beach, Truro, MA in March 2022, U.S. Geological Survey Field Activity 2022-015-FA: data release DOI:10.5066/P9GEVWG1, U.S. Geological Survey, Reston, VA.

   Online Links:

   • https://doi.org/10.5066/P9GEVWG1
   • https://www.sciencebase.gov/catalog/item/62dee095d34e952be909417b

   Other_Citation_Details:

   Suggested citation: 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 Beach, Truro, MA in March 2022, U.S. Geological Survey Field Activity 2022-015-FA: U.S. Geological Survey data release, https://doi.org/10.5066/P9GEVWG1.

2. What geographic area does the data set cover?

   West_Bounding_Coordinate: -70.07980107
   East_Bounding_Coordinate: -70.07413822
   North_Bounding_Coordinate: 42.05314809
   South_Bounding_Coordinate: 42.04938367
   

3. What does it look like?

   https://www.sciencebase.gov/catalog/file/get/62dff9eed34e952be90980ea?name=2022015FA_Truro_ortho_browse.JPG&allowOpen=true (JPEG)

   Real 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: 10-Mar-2022

   Currentness_Reference:

   ground condition; represents the state of the beach on March 10, 2022

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 4122 x 4635, 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 0.1
      Ordinates (y-coordinates) are specified to the nearest 0.1
      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?

   2022015FA_Truro_Orthomosaic_10cm_cog.tif

   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:	14
   Maximum:	255

   Band_2

   Green wavelength band (Source: Agisoft Metashape)

   Range of values
   Minimum:	11
   Maximum:	255

   Band_3

   Blue wavelength band (Source: Agisoft Metashape)

   Range of values
   Minimum:	0
   Maximum:	255

   Entity_and_Attribute_Overview:

   The orthomosaic is a full-color LZW-compressed cloud-optimized GeoTIFF with an 8-bit unsigned sample type. There are no 'no-data' values. The filename is formatted as "2022015FA_Truro_Orthomosaic_10cm_cog.tif", where 2022015FA is the USGS Field activity ID, Truro (Head of the Meadow Beach) is the location, Orthomosaic is the product type, 10cm indicates the resolution of the grid, and cog is cloud-optimized GeoTIFF.

   Entity_and_Attribute_Detail_Citation: USGS Field Activity 2022-015-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
2. Who also contributed to the data set?
3. To whom should users address questions about the data?
   Jin-Si R. Over

   U.S. Geological Survey, Woods Hole Coastal and Marine Science Center

   384 Woods Hole Rd

   Woods Hole, MA
   

   508-548-8700 x2297 (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: Jul-2022 (process 1 of 1)

   A Digital Surface Model (DSM) was created in Agisoft Metashape v. 1.8.1 using the following general steps (see Over and others, 2021):
   1. The project was created with imagery (located in larger work citation 2022015FA_Truro_f1.zip) and position (located in larger work citation 2022015FA_Truro_f1_photolocations.csv) data imported with the NAD83(2011)/UTM19N and NAVD88 datums. An 0.15 m GNSS/IPS offset in the z direction was used to represent the approximate offset of the GNSS mount and camera on the Helikite. Photos were aligned at a low accuracy so that GCPs could be automatically detected in the point cloud. Eighteen GCPs (2022015FA_Truro_nav_GCPs.csv) were located.
   2. Accuracies for the GCPs and camera positions were set to 0.02 m and 0.10 m, respectively, but the positions were only used as check points and to speed up alignment. The photos were re-aligned with high accuracy (the pixels were not subsampled to increase processing speed) using a keypoint limit of 40,000 and unlimited tie points. Alignment uses the positions and matching pixels between images to create point clouds and puts the imagery into a real-world spatial context. Photos that failed to align/find tie points contained breaking waves and water.
   3. The Metashape software used least squares to refine and optimize the camera positions, GCPs, and lens model with gradual selection and optimization parameters of: Ru = 15, Pa = 4, and Re = 0.35 to minimize reprojection error, or the distance between the measured points and the software created points.
   4. A dense point cloud was generated using high-quality (images were not subsampled) and a low frequency filtering algorithm. The dense point cloud was then edited to remove noise by filtering with point confidence before generating an interpolated DSM (the software calls all models elevation models, but a surface model includes vegetation/canopy returns, a terrain model would be only bare earth returns).
   5. The DSM was used to build an RGB averaged orthomosaic, which was then exported from the software at a resolution of 10 cm in NAD83(2011)/UTM Zone 19N (ESPG:6348).
   6. The orthorectified product was 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. Person who carried out this activity:
   

   Jin-Si R. Over

   U.S Geological Survey, Woods Hole Coastal and Marine Science Center

   Geographer

   384 Woods Hole Rd

   Woods Hole, MA
   

   508-548-8700 x2297 (voice)

   jover@usgs.gov

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

   Online Links:

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

   Other_Citation_Details:

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

   Over, Jin-Si R., Sherwood, Christopher R., Traykovski, Peter A., Brosnahan, Sandra M., Martini, Marinna A., Marsjanik, Eric, and Borden, Jonathan S., 2021, Topographic and bathymetric data, sediment samples, and beach imagery collected at Head of the Meadow, Truro in March 2020: data release DOI:10.5066/P9KSG1RQ, U.S. Geological Survey, Reston, VA.

   Online Links:

   • https://doi.org/10.5066/P9KSG1RQ

   Other_Citation_Details:

   This publication is the 2020 field data at Head of the Meadow Beach.

   Over, Jin-Si R., Sherwood, Christopher R., and Traykovski, Peter 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: data release DOI:10.5066/P9D94NZ3, U.S. Geological Survey, Reston, VA.

   Online Links:

   • https://doi.org/10.5066/P9D94NZ3

   Other_Citation_Details:

   This publication is the 2021 field data at Head of the Meadow Beach.

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 (GCP) datasets and metadata are available in the imagery and navigational components of the larger work citation. No color corrections were applied. GCP error in the Metashape project was used to assess overall error in the product.
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 cm. However, using these values in Metashape returned a poor product so the accuracy was loosened to 10 cm and unchecked as positional control points [NG2]to accommodate the unknown horizontal offset of the GPS to the camera and to rely more on the GCPs, which have a theoretical accuracy of 1-2 cm. The horizontal root mean square error (RMSE) of the GCPs was xy: 0.092, 0.104 (m). The final product was compared to the previous survey at Head of the Meadow (see second cross-reference) and the orthomosaics align at stable features.
3. How accurate are the heights or depths?
   There are no vertical positions associated with this data product.
4. Where are the gaps in the data? What is missing?
   The structure-from-motion process that built the digital surface model (DSM) and then the orthomosaic uses all the available imagery and location information at the start; however 1568/1634 images aligned in the software to produce the final product and any data gaps 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. The extent is greater than that of the digital surface model in the larger citation because it includes water and edges that do not photogrammetrically reconstruct.

How can someone get a copy of the data set?

1. Who distributes the data set? (Distributor 1 of 1)
   
   U.S. Geological Survey - ScienceBase

   Denver Federal Center, Building 810, Mail Stop 302

   Denver, CO
   

   1-888- 275-8747 (voice)

   sciencebase@usgs.gov
2. What's the catalog number I need to order this data set? GeoTIFF file 2022015FA_Truro_Orthomosaic_10cm_cog.tif is a full-color orthomosaic with an 8-bit unsigned sample type.
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 (version 1.0.0) 8-bit unsigned sample type GeoTIFF format Size: 19.1
     Network links:	https://www.sciencebase.gov/catalog/file/get/62dff9eed34e952be90980ea https://www.sciencebase.gov/catalog/item/62dff9eed34e952be90980ea https://doi.org/10.5066/P9GEVWG1

   • Cost to order the data: None.

5. What hardware or software do I need in order to use the data set?
   These data are available as a 32-bit floating point GeoTIFF image. To utilize these data, the user must have an image viewer, image processing, or GIS software package capable of importing a GeoTIFF image.

Who wrote the metadata?

Dates:

Last modified: 19-Sep-2022

Metadata author:

Jin-Si R. Over

U.S. Geological Survey, Woods Hole Coastal and Marine Science Center

Geographer

U.S. Geological Survey

Woods Hole, MA

508-548-8700 x2297 (voice)

whsc_data_contact@usgs.gov

Contact_Instructions:

The metadata contact email address is a generic address in the event the person is no longer with USGS.

Metadata standard:

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