Orthomosaics of Pea Island National Wildlife Refuge DUNEX Site, North Carolina in September and October 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?
   Over, Jin-Si R., 20220607, Orthomosaics of Pea Island National Wildlife Refuge DUNEX Site, North Carolina in September and October 2021: data release DOI:10.5066/P9DPZZG2, 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/P9DPZZG2
   • https://www.sciencebase.gov/catalog/item/623dcdfdd34e915b67d65c5b

   This is part of the following larger work.
   Over, Jin-Si R., Sherwood, Christopher R., Traykovski, Peter A., Brosnahan, Sandra M., Olson, Alex J., and Randall, Noa R., 2022, DUNEX topographic, bathymetric, and supporting GPS data collected in Pea Island National Wildlife Refuge, North Carolina 2020-2021: data release DOI:10.5066/P9DPZZG2, U.S. Geological Survey, Reston, VA.

   Online Links:

   • https://doi.org/10.5066/P9DPZZG2
   • https://www.sciencebase.gov/catalog/item/623dca6cd34e915b67d65110

   Other_Citation_Details:

   Over, J.R., Sherwood, C.R., Traykovski, P.A., Olson, A.J., Randall, N.R., and Brosnahan, S.M., 2022, DUNEX topographic, bathymetric, and supporting GPS data collected in Pea Island National Wildlife Refuge, North Carolina 2020-2021: U.S Geological Survey data release, https://doi.org/10.5066/P9DPZZG2.

2. What geographic area does the data set cover?

   West_Bounding_Coordinate: -75.48144554
   East_Bounding_Coordinate: -75.47881170
   North_Bounding_Coordinate: 35.68031925
   South_Bounding_Coordinate: 35.67433487
   

3. What does it look like?

   https://www.sciencebase.gov/catalog/file/get/623dcdfdd34e915b67d65c5b?name=PINWR_ortho_browse.JPG&allowOpen=true (JPEG)

   Example section of an orthomosaic of the Pea Island site.

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

   Calendar_Date: 07-Sep-2021

   Currentness_Reference:

   ground condition: data represent nine days of collection between September 2021 and October 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, 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: 18
      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?

   2021029FA_PINWR_Ortho_10cm_UTM18N_09-07_cog.tif

   A raster dataset (cloud optimized GeoTIFF format) with encoded RGB values of DUNEX Pea Island National Wildlife Refuge site, North Carolina on September 7, 2021. Pixel resolution is 10-cm. Pixel based raster matrix with 3 layers of information for each pixel. Accuracy of GCPs set to 0.01 m. Based off of the GCP method the total horizontal accuracy estimate is 0.028 m. (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

   2021029FA_PINWR_Ortho_10cm_UTM18N_09-08_cog.tif

   A raster dataset (cloud optimized GeoTIFF format) with encoded RGB values of DUNEX Pea Island National Wildlife Refuge site, North Carolina on September 8, 2021. Pixel resolution is 10-cm. Pixel based raster matrix with 3 layers of information for each pixel. Accuracy of GCPs set to 0.01 m. Based off of the GCP method the total horizontal accuracy estimate is 0.072 m and the vertical accuracy estimate is 0.033 m. (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

   2021029FA_PINWR_Ortho_10cm_UTM18N_09-11_cog.tif

   A raster dataset (cloud optimized GeoTIFF format) with encoded RGB values of DUNEX Pea Island National Wildlife Refuge site, North Carolina on September 11, 2021. Pixel resolution is 10-cm. Pixel based raster matrix with 3 layers of information for each pixel. Accuracy of GCPs set to 0.01 m. Based off of the GCP method the total horizontal accuracy estimate is 0.040 m. (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

   2021029FA_PINWR_Ortho_10cm_UTM18N_09-19_cog.tif

   A raster dataset (cloud optimized GeoTIFF format) with encoded RGB values of DUNEX Pea Island National Wildlife Refuge site, North Carolina on September 19, 2021. Pixel resolution is 10-cm. Pixel based raster matrix with 3 layers of information for each pixel. Accuracy of GCPs set to 0.01 m. Based off of the GCP method the total horizontal accuracy estimate is 0.021 m and the vertical accuracy estimate is 0.013 m. (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

   2021029FA_PINWR_Ortho_10cm_UTM18N_0925_cog.tif

   A raster dataset (cloud optimized GeoTIFF format) with encoded RGB values of DUNEX Pea Island National Wildlife Refuge site, North Carolina on September 25, 2021. Pixel resolution is 10-cm. Pixel based raster matrix with 3 layers of information for each pixel. There were no GCPs in this survey, suggest using conservative 0.050 m horizontal error estimate. (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

   2021029FA_PINWR_Ortho_10cm_UTM18N_09-26_cog

   A raster dataset (cloud optimized GeoTIFF format) with encoded RGB values of DUNEX Pea Island National Wildlife Refuge site, North Carolina on September 26, 2021. Pixel resolution is 10-cm. Pixel based raster matrix with 3 layers of information for each pixel. Accuracy of GCPs set to 0.01 m. Based off of the GCP method the total horizontal accuracy estimate is 0.084 m. (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

   2021029FA_PINWR_Ortho_10cm_UTM18N_10-03_cog.tif

   A raster dataset (cloud optimized GeoTIFF format) with encoded RGB values of DUNEX Pea Island National Wildlife Refuge site, North Carolina on October 3, 2021. Pixel resolution is 10-cm. Pixel based raster matrix with 3 layers of information for each pixel. Accuracy of GCPs set to 0.01 m. Based off of the GCP method the total horizontal accuracy estimate is 0.160 m. (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

   2021029FA_PINWR_Ortho_10cm_UTM18N_10-12_cog.tif

   A raster dataset (cloud optimized GeoTIFF format) with encoded RGB values of DUNEX Pea Island National Wildlife Refuge site, North Carolina on October 12, 2021. Pixel resolution is 10-cm. Pixel based raster matrix with 3 layers of information for each pixel. All GCPs were used as check points in the 4D align, total xy check point error (m): 0.032, 0.014. (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

   2021029FA_PINWR_Ortho_10cm_UTM18N_10-19_cog.tif

   A raster dataset (cloud optimized GeoTIFF format) with encoded RGB values of DUNEX Pea Island National Wildlife Refuge site, North Carolina on October 19, 2021. Pixel resolution is 10-cm. Pixel based raster matrix with 3 layers of information for each pixel. Accuracy of GCPs set to 0.010 m; B22 and B33 were removed due to suspect values. Imagery not processed in 4D due to poor alignment and high GCP errors that suggest a larger problem with the specific imagery and GCP dataset. Based off of the GCP method the total horizontal accuracy estimate is 0.789 m. However, on inspection with other raster products the horizontal accuracy is likely less than 0.20 m. Use with caution. (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 nine RGB cloud optimized GeoTIFF images. The horizontal projection is in NAD83(2011)/UTM Zone 18N. There are 'no-data' values within the products are 255.

   Entity_and_Attribute_Detail_Citation: USGS Field Activity 2021-029-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, Northeast Region: Woods Hole Coastal and Marine Science Center

   U.S. Geological Survey

   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: Feb-2022 (process 1 of 2)

   Digital Surface Model was created in Agisoft Metashape v. 1.8.1 using the following general steps (see Over and others, 2021 for a more detailed explanation of methodology): 1. Imagery (located in larger work citation) and GCPs (located in larger work citation) were brought in using the NAD83(2011)/UTM Zone 18N NAVD88 datums. 2. GCPs were manually inspected on the images and blurry images were removed. GCPs that were moved during surveys, in less than three images, or were consistently in blurry images were made into checkpoints. 3. Accuracies for the GCPs were set 0.01 m or 0.10 m depending on quality of the images. Photos from each survey were aligned in 4D at high accuracy (the pixels are not subsampled for increased processing speed) with a keypoint limit of 40,000 and unlimited tie points. 4. The alignment process uses the positions and matching pixels between images to create point clouds and put the imagery into a relative spatial context. Metashape software refined and optimized the camera positions and lens model in a least squares sense to minimize the reprojection error or the distance between the measured points and the software created points. Project supported gradual selection and optimization of: Ru = 11, Pa = 6, and Re = 0.3. Individual survey GCP and product errors are calculated separately and reported in the Entity and Attribute Information. 5. A dense point cloud was generated for each survey in a separate Metashape chunk using high quality (images are not subsampled) and a low frequency filtering algorithm. 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). 5. 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 18N (ESPG:6348). Person who carried out this activity:
   

   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 x2269 (voice)

   jover@usgs.gov

   Date: Mar-2022 (process 2 of 2)

   Orthomosaics were turned into Cloud Optimized GeoTIFFs (COG) using gdal_translate with the following command:for %i in (.\*.tif) do gdal_translate %i .\cog\%~ni_cog.tif -co COMPRESS=LZW -co COPY_SRC_OVERVIEWS=YES -co BIGTIFF=YES -co TILED=YES (v. 3.1.4 accessed October 20, 2020 https://gdal.org/). Where i was the name of each geoTIFF section and a folder named cog is in the directory. Person who carried out this activity:
   

   Jin-Si R. Over

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

   Geographer

   384 Woods Hole Road

   Woods Hole, MA
   

   US

   508-458-8700 x2269 (voice)

   508-457-2310 (FAX)

   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, Tommy A., 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:

   • 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?
   Ground control points (GCPs) were used to constrain the products. See larger citation for accuracy description of GCPs.
2. How accurate are the geographic locations?
   Horizontal accuracy was estimated by comparing SfM-derived GCP positions to RTK GPS measurements. Due to the time-intensive process of placing GCPs in the field, all available GCPs were used for registration and camera optimization in the SfM processing workflow during the creation of the final products. To evaluate the horizontal positional accuracy of each orthomosaic after processing was completed, each GCP from the survey was disabled one-at-a-time using a python script to create a 'temporary check point'. With a single GCP temporarily disabled, camera optimization was performed with all lens parameters fixed, and all other GCPs enabled. The residual errors of the check point relative to its GPS-measured position were recorded. After all temporary check point iterations were complete, the horizontal root-mean-square error (RMSE) and mean-absolute error (MAE) were calculated. The resulting errors are combined with the estimated horizontal GPS uncertainty (0.010 meters) in quadrature to provide a total horizontal error estimate for each orthomosaic (see Entity and Attribute information for individual DSM error estimates). Each survey has between 0-15 GCPs associated with the survey. It should be noted that this error estimate is for areas of bare ground or low vegetation where GCPs were placed. Additional sources of error such as poor image-to-image point matching due to vegetation or uniform substrate texture (such as sand) or objects in motion resulting in poor surface reconstruction may cause localized errors in some portions of the product to exceed the estimate. The orthomosaic without GCPs is still usable because of the 4D alignment with the other survey dates, matched key and tie points, and the orthomosaics pass visual QC.
3. How accurate are the heights or depths?
   
4. Where are the gaps in the data? What is missing?
   Orthomosaics do not all cover the same extent and may extend beyond their respective DSM (located in the larger work citation).
5. How consistent are the relationships among the observations, including topology?
   Orthomosaic may appear blurry or stretched or disjointed near the edges and where vegetation, shadows, or waves interfered with the structure from motion and mosaic process.

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? The orthomosaics are available as a cloud optimized GeoTIFF files.
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:	Cloud optimized GeoTIFF in format GeoTIFF Size: 155
     Network links:	https://www.sciencebase.gov/catalog/file/get/623dcdfdd34e915b67d65c5b https://www.sciencebase.gov/catalog/item/623dcdfdd34e915b67d65c5b https://doi.org/10.5066/P9DPZZG2

   • Cost to order the data: None.

Who wrote the metadata?

Dates:

Last modified: 07-Jun-2022

Metadata author:

Jin-Si R. Over

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

Geographer

384 Woods Hole Road

Woods Hole, MA

US

508-458-8700 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.

Metadata standard:

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