RGB-averaged orthoimagery of coastal North Carolina, from 2020-05-08 to 2020-05-09

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Frequently anticipated questions:

What does this data set describe?

Title:
RGB-averaged orthoimagery of coastal North Carolina, from 2020-05-08 to 2020-05-09
Abstract:
RGB-averaged orthoimages were created from aerial imagery collected May 08 and 09, 2020, along the North Carolina coast between the Virginia-North Carolina border vicinity and Cape Lookout, North Carolina. These RGB-averaged orthoimages were created to document recovery ground conditions after Hurricane Dorian, which made landfall on the North Carolina coast on September 6, 2019. The RGB-averaged orthoimages help researchers document inter-annual changes in shoreline position and coastal morphology in response to storm events using aerial imagery collections and a structure from motion (SFM) workflow. These data can be used with geographic information systems or other software to identify topographic and shallow-water bathymetric features.
Supplemental_Information:
Additional information about the field activity from which these data were derived is available online at:
https://cmgds.marine.usgs.gov/fan_info.php?fan=2020-304-CNT
Any use of trade, product, or firm names is for descriptive purposes only and does not imply endorsement by the U.S. Government.
The raw imagery and navigation data used to produce the RGB-averaged orthoimages are available online at https://doi.org/10.5066/P9OCDOYZ. Bounding coordinates for the metadata are derived from the overall flight path and are not necessarily representative of individual RGB-averaged orthoimages product boundaries, which are split up along the coast to have more accessible data-download sizes. See image at https://www.sciencebase.gov/catalog/file/get/617352c1d34ea36449a8838b?name=Product_Boundary_Map.jpg for geographic locations used to create the data subsets.
  1. How might this data set be cited?
    Ritchie, Andrew C., 20221011, RGB-averaged orthoimagery of coastal North Carolina, from 2020-05-08 to 2020-05-09: data release DOI:10.5066/P9K3TWY7, U.S. Geological Survey, Pacific Coastal and Marine Science Center, Santa Cruz, CA.

    Online Links:

    This is part of the following larger work.

    Ritchie, Andrew C., Over, Jin-Si R., Kranenburg, Christine J., Brown, Jenna A., Buscombe, Daniel D., Sherwood, Christopher R., Warrick, Jonathan A., and Wernette, Phillipe A., 2022, Aerial photogrammetry data and products of the North Carolina coast: data release DOI:10.5066/P9K3TWY7, U.S. Geological Survey, Reston, VA.

    Online Links:

  2. What geographic area does the data set cover?
    West_Bounding_Coordinate: -76.54958089
    East_Bounding_Coordinate: -75.45586710
    North_Bounding_Coordinate: 36.55128178
    South_Bounding_Coordinate: 34.57597419
  3. What does it look like?
    https://www.sciencebase.gov/catalog/file/get/62680f97d34e76103ccfd2b0?name=202002_RGBavg_NC_example.JPG&allowOpen=true (JPEG)
    Example segment of a RGB-averaged ortho from 2020-02.
  4. Does the data set describe conditions during a particular time period?
    Calendar_Date: 08-May-2020
    Currentness_Reference:
    Ground condition, data was collected on two days: May 8 and 9, 2020.
  5. What is the general form of this data set?
    Geospatial_Data_Presentation_Form: raster digital data (GeoTIFF)
  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 0.25
      Ordinates (y-coordinates) are specified to the nearest 0.25
      Planar coordinates are specified in meters
      The horizontal datum used is NAD83_National_Spatial_Reference_System_2011.
      The ellipsoid used is Geodetic Reference System 80.
      The semi-major axis of the ellipsoid used is 6378137.000000.
      The flattening of the ellipsoid used is 1/298.257222.
  7. How does the data set describe geographic features?
    20200508-09_RGBavg_VA_to_Oregon_Inlet_NAD83_2011_UTM18N_25cm_cog.tif
    A raster dataset (unsigned 8-bit integer cloud-optimized GeoTIFF format) with encoded RGB values of the North Carolina coast from the Virginia-North Carolina state border to Oregon Inlet, as recorded on May 8 and 9, 2020. Pixel resolution is 25-cm. Pixel-based raster matrix includes 3 layers of information for each pixel and a fourth alpha, or transparency, band for encoding no-data values. (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
    Band_4
    Alpha band, where 0 is transparent, or no-data, and 255 is opaque, or has data. (Source: Agisoft Metashape)
    Range of values
    Minimum:0
    Maximum:255
    20200508-09_RGBavg_Oregon_Inlet_to_Hatteras_Inlet_NAD83_2011_UTM18N_25cm_cog.tif
    A raster dataset (unsigned 8-bit integer cloud-optimized GeoTIFF format) with encoded RGB values of the North Carolina coast from Oregon Inlet to Hatteras Inlet, as recorded on May 8 and 9, 2020. Pixel resolution is 25-cm. Pixel-based raster matrix includes 3 layers of information for each pixel and a fourth alpha, or transparency, band for encoding no-data values. (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
    Band_4
    Alpha band, where 0 is transparent, or no-data, and 255 is opaque, or has data. (Source: Agisoft Metashape)
    Range of values
    Minimum:0
    Maximum:255
    20200508-09_RGBavg_Hatteras_Inlet_to_Ocracoke_Inlet_NAD83_2011_UTM18N_25cm_cog.tif
    A raster dataset (unsigned 8-bit integer cloud-optimized GeoTIFF format) with encoded RGB values of the North Carolina coast from Hatteras Inlet to Ocracoke Inlet, as recorded on May 8 and 9, 2020. Pixel resolution is 25-cm. Pixel-based raster matrix includes 3 layers of information for each pixel and a fourth alpha, or transparency, band for encoding no-data values. (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
    Band_4
    Alpha band, where 0 is transparent, or no-data, and 255 is opaque, or has data. (Source: Agisoft Metashape)
    Range of values
    Minimum:0
    Maximum:255
    20200508-09_RGBavg_Ocracoke_Inlet_to_Cape_Lookout_NAD83_2011_UTM18N_25cm_cog.tif
    A raster dataset (unsigned 8-bit integer cloud-optimized GeoTIFF format) with encoded RGB values of the North Carolina coast from Ocracoke Inlet to Cape Lookout, as recorded on May 8 and 9, 2020. Pixel resolution is 25-cm. Pixel resolution is 25-cm. Pixel-based raster matrix includes 3 layers of information for each pixel and a fourth alpha, or transparency, band for encoding no-data values. (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
    Band_4
    Alpha band, where 0 is transparent, or no-data, and 255 is opaque, or has data. (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) UTM Zone 18N for all ortho products. The 'no-data' values are encoded in the alpha channel (Band 4) as 0 (no data) and 255 (data). Zeros populate the area outside the orthoimage but within the rectangular extent of the raster bounds. Pixel-based raster matrix includes 3 RGB layers of information for each pixel. There are four RGB(A) orthoimage GeoTIFFs. The filename for each file is formatted as "date_product_location_to_location_CRS_resolution_cog.tif", where date is the date the raw aerial images were collected (in YYYYMMDD-MMDD format), product is RGBavg that indicates the orthoimage blending mode in Agisoft Metashape, location_to_location is the specific geographic location in North Carolina of the northern extent to the southern extent, CRS is the horizontal coordinate reference system used, resolution is the horizontal pixel resolution of the grid, and 'cog' denotes the product is a cloud-optimized GeoTIFF.
    Entity_and_Attribute_Detail_Citation: USGS

Who produced the data set?

  1. Who are the originators of the data set? (may include formal authors, digital compilers, and editors)
    • Andrew C. Ritchie
  2. Who also contributed to the data set?
  3. To whom should users address questions about the data?
    U.S. Geological Survey, Pacific Coastal and Marine Science Center
    Attn: PCMSC Science Data Coordinator
    2885 Mission Street
    Santa Cruz, CA

    831-427-4747 (voice)
    pcmsc_data@usgs.gov

Why was the data set created?

U.S. Geological (USGS) researchers use the RGB-averaged orthoimages to assess future coastal vulnerability, nesting habitats for wildlife, and provide data for hurricane impact models. The products span the coast over both highly developed towns and natural areas, including federal lands. This research is part of the USGS Remote Sensing Coastal Change Project.

How was the data set created?

  1. From what previous works were the data drawn?
    Aerial Imagery (source 1 of 5)
    Kranenburg, Christine, Ritchie, Andrew C, Jennifer (Jenna) A Brown, Over, Jin-Si R, Buscombe, Daniel D, Sherwood, Christopher R, Warrick, Jonathan A, and Wernette, Phillipe A, 2022, Aerial imagery of the North Carolina coast: 2020-05-08 and 2020-05-09: U.S. Geological Survey, St. Petersburg Coastal and Marine Science Center.

    Online Links:

    Type_of_Source_Media: Digital
    Source_Contribution: The data in this release are used to make SFM products.
    Aerial Imagery 4D dataset 1 (source 2 of 5)
    Kranenburg, Christine J, Ritchie, Andrew C, Brown, Jenna A, Over, Jin-Si R, Sherwood, Christopher R, Warrick, Jonathan A, and Wernette, Phillipe A, 2022, Aerial imagery of the North Carolina coast: 2019-10-11: U.S. Geological Survey, St. Petersburg Coastal and Marine Science Center.

    Online Links:

    Type_of_Source_Media: Digital
    Source_Contribution:
    The data in this release are used in the 4D alignment Metashape SFM Batch2a process.
    Aerial Imagery 4D dataset 2 (source 3 of 5)
    Kranenburg, Christine J, Ritchie, Andrew C, Brown, Jenna A, Over, Jin-Si R, Sherwood, Christopher R, Warrick, Jonathan A, and Wernette, Phillipe A, 2022, Aerial imagery of the North Carolina coast: 2019-11-26: U.S. Geological Survey, St. Petersburg Coastal and Marine Science Center.

    Online Links:

    Type_of_Source_Media: Digital
    Source_Contribution:
    The data in this release are used in the 4D alignment Metashape SFM Batch2a process.
    Aerial Imagery 4D dataset 3 (source 4 of 5)
    Kranenburg, Christine J, Ritchie, Andrew C, Brown, Jenna A, Over, Jin-Si R, Sherwood, Christopher R, Warrick, Jonathan A, and Wernette, Phillipe A, 2022, Aerial imagery of the North Carolina coast: 2020-02-08 to 2020-02-09: U.S. Geological Survey, St. Petersburg Coastal and Marine Science Center.

    Online Links:

    Type_of_Source_Media: Digital
    Source_Contribution:
    The data in this release are used in the 4D alignment Metashape SFM Batch2a process.
    Ground Control Points (source 5 of 5)
    Brown, Jenna A., Sherwood, Christopher R., Martini, Marinna, Kranenburg, Christine J., and Over, Jin-Si R., 2021, Ground Control Point Data from the Outer Banks, North Carolina, post-Hurricane Dorian, October 2019.

    Online Links:

    Type_of_Source_Media: Digital and/or Hardcopy
    Source_Contribution:
    The Ground Control Points are used in the SFM process and to assess horizontal and vertical positional accuracy.
  2. How were the data generated, processed, and modified?
    Date: Feb-2022 (process 1 of 2)
    On a workstation (AMD Threadripper 3960X /AsRock TRX40 Creator motherboard/256GB 3000MHz RAM) using Win10x64, aerial imagery and associated positional data (Kranenburg and others 2022a; 2022b; 2022c; 2022d) and a single ground control point (Brown and others, 2021) were brought into an Agisoft Metashape Pro (v. 1.6.5) project to align in a 4D manner (see Sherwood and others, 2019). Only one ground control point, GCP 34, was used as a control point to help 'lock' in the camera positions, whereas the rest of the points were used as independent vertical check points (that is, they were not placed in Metashape). See Kranenburg and others (2022a), for Metashape Reference Settings inputs. The additional imagery improves the horizontal and vertical accuracy, but similar products can be reproduced without them. The following steps were performed on the Metashape project in the geographic coordinate system NAD83(2011) in ellipsoid height following the general guidance of Over and others (2021): 1. Separate camera models and camera groups were created for each flight date aligned in 4D. Note that multiple imagery datasets are used in the overall processing effort to produce the end individual survey products that this metadata file covers. 2. Imagery (with positions) are aligned in 4D to create a point cloud using a 'High' alignment setting, keypoint limit of 70,000, tiepoint limit of 0, generic preselection selected, and reference preselection via source selected. The tiepoint accuracy was set to 1 pixel. 3. 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 two iterations of the 'Reprojection accuracy' filer at a level of 0.3 (in the second iteration the 'fit additional corrections' option was turned on). With each filter, iteration points are selected, deleted, and then the camera model is optimized to refine the focal length, cx, cy, k1, k2, k3, p1, and p2 camera model coefficients. 4. Natural breaks in the final alignment product were identified based on bodies of water or the extreme northern and southern ends of a flight (see Product_Boundary_Map.jpg at https://doi.org/10.5066/P9K3TWY7). The breaks and dates of imagery in the 4D process are used for ease and speed of processing. The boundaries used for the 2020-05 dataset are the Virginia-North Carolina border vicinity to Oregon Inlet, Oregon Inlet to Hatteras Inlet, Hatteras Inlet to Ocracoke Inlet, Ocracoke Inlet to Cape Lookout.
    For each region, sub-chunks were created for each mission (one or two flight-days, usually adjacent) by iteratively copying the original 4D chunk and removing all camera groups not part of a single mission. Note that this particular metadata file only covers the 2020-05 dataset. Processing took place starting in June 2021 and into February 2022, the latest processing in YYYYMM is given in the Process Date. Data sources used in this process:
    • Aerial Imagery
    • Ground Control Points
    • Aerial Imagery 4D dataset 1
    • Aerial Imagery 4D dataset 2
    • Aerial Imagery 4D dataset 3
    Date: 26-Jul-2021 (process 2 of 2)
    From the previous process step, each 'chunk' is processed as follows to create the final DEM products for each flight date: 1. Targeted imagery sets in the aligned chunk are copied from the workstation to a new Agisoft Metashape Pro. project on the U.S Geological Survey Tallgrass high-performance computing network for processing on CPU and GPU nodes (https://www.usgs.gov/core-science-systems/sas/arc/machine-access). 2. If multiple flight dates were flown for this chunk, imagery from one date is targeted, and the rest are disabled (this is then switched for each flight date in the chunk after the final step and steps 3-6 are repeated). 3. A high quality dense point cloud is generated for the chunk with 'mild' filtering and the options to calculate point color and point confidence selected. 4. Dense point cloud is filtered using the 'Filter by Confidence' tool using the range 0-2, these points selected at this range are classified as low noise. 5. A DEM is built from the dense point cloud with interpolation enabled and without the points classified as low noise (interpolated DEM not included in this publication). 6. An orthophoto is built from the interpolated DEM using the blending mode 'average'. 7. The orthorectified product is exported in NAD83(2011) UTM Zone 18N with a 0.25-meter cell size and integer boundary intervals. 8. Orthorectified product is 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=LZW -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. Note that this metadata covers only the 2020-05 products even though the processing steps use multiple datasets.
  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, 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 DEMs and ortho products.
    NOAA Office for Coastal Management (OCM Partners), 2019, 2018 USACE NCMP Post-Florence Topobathy Lidar DEM: Southeast Coast (VA, NC, SC): Data Series 57345, Office for Coastal Management, Charleston, SC.

    Online Links:

    Other_Citation_Details:
    This data set was used to qualitatively assess the horizontal and accuracy of the RGB-averaged products.
    NOAA Office for Coastal Management (OCM Partners), 2019, 2019 USACE NCMP DUNEX Topobathy Lidar DEM: East Coast (NC, VA): Data Series 60197, Office for Coastal Management, Charleston, SC.

    Online Links:

    Other_Citation_Details:
    This data set was used to qualitatively assess the horizontal and accuracy of the RGB-averaged products.
    Sherwood, Christopher R., Warrick, Jonathan A., Hill, Andrew D., Ritchie, Andrew C., and Plant, Nathaniel G., 2018, Rapid, remote assessment of Hurricane Matthew impacts using four-dimensional structure-from-motion photogrammetry: Professional Paper DOI:10.2112/JCOASTRES-D-18-00016.1, Journal of Coastal Research, Online.

    Online Links:

    Other_Citation_Details:
    This publication includes the general methodology described for processing imagery in Metashape in four-dimensions to produce DEMs and ortho products.

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

  1. How well have the observations been checked?
    The source imagery and positional information and metadata that were used to create these photogrammetrically derived products are available at Kranenburg and others (2022a). Information on the horizontal and vertical accuracies of the source data can be found within the data release metadata. Horizontal accuracy of the RGB-averaged orthoimages is assessed using published ground control points (GCPs) and a qualitative assessment with published lidar datasets (OCM Partners, 2018; 2019). It should be noted that accuracy estimates of the products are 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 or moving objects resulting in poor surface reconstruction may cause localized errors in some portions of the orthoimage to exceed accuracy values. Processing imagery in 4D (see processing steps) aims to keep related products precise within the reported accuracies.
  2. How accurate are the geographic locations?
    Horizontal accuracy is affected by the source data and photogrammetry processing and difficult to quantitatively test. One ground control point (GCP 34; 0.037-meter xy accuracy) and post-processed kinematic (PPK) camera positions (Kranenburg and others, 2022a; 2022b; 2022c; 2022d) were used to create the final SfM products in 4D. The horizontal (x,y) error of control point GCP 34 after batch co-alignment and error reduction in the Metashape project (see processing steps) was 0.040,-0.048 m. These values do not represent the absolute horizontal georeferencing accuracy of the product but provide a better sense of the overall photogrammetry processing accuracy. Due to the nature of the in-place GCPs being difficult to distinguish in the orthoimages at their published resolution, no further horizontal accuracy assessment was done with them. A qualitative analysis of gridded first-return lidar data at stable points (OCM Partners, 2018; 2019) supports these base horizontal accuracy estimates.
  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?
    All collected aerial imagery was used. The orthoimagery products have not been cropped and include coverage of water. Orthoimages were created from interpolated DEMs in Metashape. GeoTIFFs are cloud-optimized.
  5. How consistent are the relationships among the observations, including topology?
    There are a total of four orthoimagery products included in this dataset. The products may appear blurry or distorted near tall buildings, areas of poorer image overlap, and near water (waves, ponds, shorelines), where the data return is often sparse, noisy, and erroneous. No color corrections were applied. GeoTIFFs are in full-color. The blending mode of the orthoimagery uses a weighted average value of all the pixels from individual photos (https://www.agisoft.com/pdf/metashape-pro_1_6_en.pdf - see Blending mode; accessed June 2020).

How can someone get a copy of the data set?

Are there legal restrictions on access or use of the data?
Access_Constraints None
Use_Constraints Public domain data from the U.S. Government are freely redistributable with proper metadata and source attribution. Please recognize the U.S. Geological Survey (USGS) as the source of this information.
  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
    United States

    1-888-275-8747 (voice)
    sciencebase@usgs.gov
  2. What's the catalog number I need to order this data set? The four three-band RGB-averaged cloud-optimized GeoTIFF ortho products are deflate compressed, have 25 cm resolution, and represent the coast of North Carolina on 2020-05-08 and 2020-05-09.
  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 on any other system or for general or scientific purposes, nor shall the act of distribution constitute any such warranty. 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?

Who wrote the metadata?

Dates:
Last modified: 07-Nov-2023
Metadata author:
U.S. Geological Survey, Pacific Coastal and Marine Science Center
Attn: PCMSC Science Data Coordinator
2885 Mission Street
Santa Cruz, CA

831-427-4747 (voice)
pcmsc_data@usgs.gov
Metadata standard:
Content Standard for Digital Geospatial Metadata (FGDC-STD-001-1998)
This page is <https://cmgds.marine.usgs.gov/catalog/pcmsc/DataReleases/ScienceBase/DR_P9K3TWY7/202005_Ortho_NC_metadata.faq.html>
Generated by mp version 2.9.51 on Fri Nov 17 13:30:50 2023