True color and multispectral ortho products created from UAS operations at North Core Banks, NC in October 2022

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Frequently anticipated questions:

What does this data set describe?

Title:
True color and multispectral ortho products created from UAS operations at North Core Banks, NC in October 2022
Abstract:
These data map in high detail surficial cross-sections of North Core Banks, a barrier island in Cape Lookout National Seashore, NC, in October 2022. U.S. Geological Survey field efforts are part of an interagency agreement with the National Park Service to monitor the recovery of the island from Hurricanes Florence (2018) and Dorian (2019). Three sites of outwash, overwash, and pond formation were targeted for extensive vegetation ground-truthing, sediment samples, bathymetric mapping with a remote-controlled surface vehicle, and uncrewed aerial systems (UAS) flights to collect multispectral imagery. Five semi-permanent ground control points were also installed and surveyed to act as control for additional aerial imagery collects via plane. UAS imagery were processed in Agisoft Metashape (v. 1.8.1) with surveyed temporary ground control points to produce calibrated multispectral (red, blue, green, red edge, near infrared, and panchromatic) orthoimages and digital surface models.
Supplemental_Information:
For more information about the WHCMSC Field Activity, see https://cmgds.marine.usgs.gov/fan_info.php?fan=2022034FA. Bounding coordinates represent the maximum extent of all the images, not the individual sites. The Altum-PT and Ricoh GRII were flown at the same time; flights 01 and 02 cover the extent of “New Pond 1”, 03 and 04 cover the extent of “New Pond 3” and 05 and 06 cover the extent of “New Pond 0”.
  1. How might this data set be cited?
    Over, Jin-Si R., and Cramer, Jennifer M., 20230328, True color and multispectral ortho products created from UAS operations at North Core Banks, NC in October 2022: data release DOI:10.5066/P99IV3FC, 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.

    Over, Jin-Si R., Sherwood, Christopher R., Cramer, Jennifer M., Evans, Alexandra D., and Zeigler, Sara L., 2023, Topographic, bathymetric, multispectral, vegetation, sediment, and supporting GPS data collected on North Core Banks, Cape Lookout National Seashore, North Carolina in October 2022, U.S. Geological Survey Field Activity 2022-034-FA: data release DOI:10.5066/P99IV3FC, U.S. Geological Survey, Reston, VA.

    Online Links:

    Other_Citation_Details:
    Suggested citation: Over, J.R., Sherwood, C.R., Cramer, J.M., Evans, A.D., and Zeigler, S.L, 2023, Topographic, bathymetric, multispectral, vegetation, sediment, and supporting GPS data collected on North Core Banks, Cape Lookout National Seashore, North Carolina in October 2022, U.S. Geological Survey Field Activity 2022-034-FA: U.S. Geological Survey data release, https://doi.org/10.5066/P99IV3FC.
  2. What geographic area does the data set cover?
    West_Bounding_Coordinate: -76.27193750
    East_Bounding_Coordinate: -76.22442000
    North_Bounding_Coordinate: 34.92498270
    South_Bounding_Coordinate: 34.88848350
  3. What does it look like?
    https://www.sciencebase.gov/catalog/file/get/63adf792d34e92aad3ca5b79?name=2022034FA_NCB_ortho_browse.JPG&allowOpen=true (JPEG)
    Browse graphic of the ortho products, from left to right, a false color image, true color image, and the panchromatic orthoimage.
  4. Does the data set describe conditions during a particular time period?
    Calendar_Date: 19-Oct-2022
    Currentness_Reference:
    Ground condition; multiple survey days.
  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: -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 6378137.000000.
      The flattening of the ellipsoid used is 1/298.257222101.
  7. How does the data set describe geographic features?
    2022034FA_NCB_NP0_Altum-PT_Ortho_5band_10cm_UTM18N_cog.tif
    Multispectral (B, G, R, Re, NIR) 32-bit floating point cloud optimized GeoTIFF of New Pond 0. Values have been transformed from digital numbers into reflectance values (unitless). No-data value is -32767. (Source: USGS)
    Blue
    Blue wavelength (475 nm center) band reflectance (Source: Agisoft Metashape)
    Range of values
    Minimum:0.000
    Maximum:0.936
    Green
    Green wavelength (560 nm center) band reflectance (Source: Agisoft Metashape)
    Range of values
    Minimum:0.000
    Maximum:1.131
    Red
    Red wavelength (668 nm center) band reflectance (Source: Agisoft Metashape)
    Range of values
    Minimum:0.000
    Maximum:1.03
    Red edge
    Red edge wavelength (717 nm center) band reflectance (Source: Agisoft Metashape)
    Range of values
    Minimum:0.000
    Maximum:1.099
    Near-infrared
    Near-infrared wavelength (842 nm center) band reflectance (Source: Agisoft Metashape)
    Range of values
    Minimum:0.000
    Maximum:1.054
    2022034FA_NCB_NP1_Altum-PT_Ortho_5band_10cm_UTM18N_cog.tif
    Multispectral (B, G, R, Re, NIR) 32-bit floating point cloud optimized GeoTIFF of New Pond 1. Values have been transformed from digital numbers into reflectance values (unitless). No-data value is -32767. (Source: USGS)
    Blue
    Blue wavelength (475 nm center) band reflectance (Source: Agisoft Metashape)
    Range of values
    Minimum:0.000
    Maximum:1.025
    Green
    Green wavelength (560 nm center) band reflectance (Source: Agisoft Metashape)
    Range of values
    Minimum:0.000
    Maximum:1.021
    Red
    Red wavelength (668 nm center) band reflectance (Source: Agisoft Metashape)
    Range of values
    Minimum:0.000
    Maximum:1.003
    Red edge
    Red edge wavelength (717 nm center) band reflectance (Source: Agisoft Metashape)
    Range of values
    Minimum:0.000
    Maximum:0.881
    Near-infrared
    Near-infrared wavelength (842 nm center) band reflectance (Source: Agisoft Metashape)
    Range of values
    Minimum:0.000
    Maximum:0.859
    2022034FA_NCB_NP3_Altum-PT_Ortho_5band_10cm_UTM18N_cog.tif
    Multispectral (B, G, R, Re, NIR) 32-bit floating point cloud optimized GeoTIFF of New Pond 3. Values have been transformed from digital numbers into reflectance values (unitless). No-data value is -32767. (Source: USGS)
    Blue
    Blue wavelength (475 nm center) band reflectance (Source: Agisoft Metashape)
    Range of values
    Minimum:0.000
    Maximum:1.000
    Green
    Green wavelength (560 nm center) band reflectance (Source: Agisoft Metashape)
    Range of values
    Minimum:0.000
    Maximum:1.000
    Red
    Red wavelength (668 nm center) band reflectance (Source: Agisoft Metashape)
    Range of values
    Minimum:0.000
    Maximum:1.000
    Red edge
    Red edge wavelength (717 nm center) band reflectance (Source: Agisoft Metashape)
    Range of values
    Minimum:0.000
    Maximum:1.000
    Near-infrared
    Near-infrared wavelength (842 nm center) band reflectance (Source: Agisoft Metashape)
    Range of values
    Minimum:0.000
    Maximum:1.000
    2022034FA_NCB_NP0_Altum-PT_Ortho_Panchromatic_2pt5cm_UTM18N_cog.tif
    Altum-PT panchromatic band cloud optimized GeoTIFF of New Pond 0. Values are digital numbers assigned as a function of a 16-bit image (2^16). No-data value is -32767. (Source: USGS)
    Band_1
    Panchromatic band (Source: Agisoft Metashape)
    Range of values
    Minimum:525
    Maximum:65535
    2022034FA_NCB_NP1_Altum-PT_Ortho_Panchromatic_2pt5cm_UTM18N_cog.tif
    Altum-PT panchromatic band cloud optimized GeoTIFF of New Pond 1. Values are digital numbers assigned as a function of a 16-bit image (2^16). No-data value is -32767. (Source: USGS)
    Band_1
    Panchromatic band (Source: Agisoft Metashape)
    Range of values
    Minimum:520
    Maximum:65535
    2022034FA_NCB_NP3_Altum-PT_Ortho_Panchromatic_2pt5cm_UTM18N_cog.tif
    Altum-PT panchromatic band cloud optimized GeoTIFF of New Pond 3. Values are digital numbers assigned as a function of a 16-bit image (2^16). No-data value is -32767. (Source: USGS)
    Band_1
    Panchromatic band (Source: Agisoft Metashape)
    Range of values
    Minimum:0
    Maximum:63780
    2022034FA_NCB_NP0_Ricoh_Ortho_3band_5cm_UTM18N_cog.tif
    True-color (RGB) cloud optimized GeoTIFF of New Pond 0. Band values are digital numbers assigned as a function of an unsigned 8-bit image (2^8). No-data value is -3.4028235e+38. (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
    2022034FA_NCB_NP1_Ricoh_Ortho_3band_5cm_UTM18N_cog.tif
    True-color (RGB) cloud optimized GeoTIFF of New Pond 1. Band values are digital numbers assigned as a function of an unsigned 8-bit image (2^8). No-data value is -3.4028235e+38. (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
    2022034FA_NCB_NP3_Ricoh_Ortho_3band_5cm_UTM18N_cog.tif
    True-color (RGB) cloud optimized GeoTIFF of New Pond 1. Band values are digital numbers assigned as a function of an unsigned 8-bit image (2^8). No-data value is -3.4028235e+38. (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
    Entity_and_Attribute_Overview:
    The horizontal projection of all ortho products is NAD83 (2011)/UTM Zone 18N (ESPG: 6347). No-data values populate the area outside the orthoimage but within the rectangular extent of the raster bounds. The naming scheme of the products is formatted as "2022034FA_location_sensor_product_resolution_CRS_cog.tif", where the location is North Core Banks (NCB) New Pond (NP) 0, 1, or 3, the sensor is either the Altum-PT or Ricoh, product is either a 5-band, 3-band, or panchromatic band ortho, resolution is in centimeters, the coordinate reference system (CRS) is UTM18N, 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)
    • 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?
    Jin-Si R. Over
    U.S. Geological Survey, Northeast Region, 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?

Multispectral ortho products are to be used for identification of vegetation and other groundcover classifications. The panchromatic band can be used to pan-sharpen the other ortho products.

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: 18-Dec-2022 (process 1 of 1)
    The ortho products were created in Agisoft Metashape v. 1.8.1 using the following general steps (see Over and others, 2021 for a more detailed methodology explanation): 1. For each site (NP0, NP1, and NP3) a project was created and Ricoh and Altum-PT imagery (located in larger work citation) was imported. 2. Photos were aligned at a low accuracy and then GCPs were automatically detected in the point cloud. Incorrect detections were removed manually. GCP positions (2022034FA_NCB_GCPs.csv located in the larger work citation) were added to the project in the reference systems NAD83(2011)/UTM Zone 18N and NAVD88 (geoid 18). Accuracies for the GCPs were set to 0.05 m and the camera positions for the Altum-PT images were turned off. The photos were then re-aligned with high accuracy (the pixels were not subsampled) 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 GCPs. The resultant point clouds were filtered using one iteration of the 'Reconstruction uncertainty' filter at a level of 12, one iteration of the 'Projection accuracy' filter at a level of 3, and three 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. At this point, multiple ‘chunks’ were created so that independent high quality dense clouds with a low-frequency filtering algorithm could be made from the Ricoh images and Altum-PT images. The dense point clouds were then edited by visual inspection and Metashape’s confidence filter to remove points with a low confidence near the edges and near water bodies. 4. Digital elevation model products were built from the dense clouds and then orthomosaics were built from these with refined seamlines. The first Altum-PT ortho product was transformed so that the bands were all divided by the reflectance normalization factor 32768 (half of the available digital number range or 100% reflectance for each band for 16-bit images) and reordered so that bands 1-5 are in wavelength order, Blue, Green, Red, Red edge, and Near-infrared, respectively. The normalization process produces values that are a unitless reflectance value between 0 and 1, where 1 would be 100% reflectance, i.e. lighter. This 5-band product was exported at 10 cm resolution. The second Altum-PT product was just the panchromatic band and was not transformed, the product was exported at 2.5 cm. The Ricoh product is an RGB product with 5 cm resolution. All products are in NAD83(2011)/UTM Zone 18N and region boundaries were rounded to the nearest 5 m interval. West and south bounds were rounded up and east and north bounds were rounded down. 5. All ortho image products were compressed and turned into a cloud-optimized GeoTIFFs (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
    U.S. Geological Survey
    Woods Hole, MA

    508-548-8700 x2297 (voice)
    jover@usgs.gov
  3. What similar or related data should the user be aware of?
    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:

    Other_Citation_Details:
    This data release contains data products that cover North Core Banks and can be used in data quality assessments and comparative elevation studies.
    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?
    The panchromatic ortho and 5-band ortho were produced from the MicaSense Altum-PT. The accuracy of the multispectral 5-band ortho product was determined by comparing the reflective value of two reflectance calibration tarps that are visible in the imagery to their established value. The RGB orthoimage produced by the Ricoh GRII imagery was not checked in this manner. Horizontal accuracy of all orthoimages was assessed using ground control points (GCPs) in the Metashape projects. It should be noted that GCP-based 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, may cause localized errors in some portions of the orthoimages 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 is difficult to quantitatively test, especially as this is the highest resolution dataset currently available in a very dynamic environment with no surveyed stable features. A cursory qualitative analysis of the UAS orthoimages compared against published ortho images with overlapping extent (Ritchie and others, 2022) indicates the products align well as can be discerned between 2.5-10 cm and 1 meter products. The horizontal root mean square error (RMSE) of the GCPs as reported from the Metashape projects for each site are given here. NP0 GCP (n=5) RMSE was xy: 0.013, 0.018 (m), NP1 GCP (n=3) RMSE was xy: 0.028, 0.032, and NP3 GCP (n=5) RMSE was xy: 0.011, 0.004 (m). These values do not represent the absolute horizontal georeferencing accuracy of the product but provide a better sense of the overall processing accuracy.
  3. How accurate are the heights or depths?
    There are no vertical positions associated with these data products, rather the encoded reflectance values in the 5-band multispectral ortho product are evaluated here. The two radiometrically calibrated reflectance tarps visible in the ortho image have known values of 0.48 (light) and 0.12 (dark). The average value of each tarp was evaluated by extracting all the values for each band within the area of each tarp in the 5-band products – the lighter tarp values were consistently lower than published and may be partially due to dirt accumulation over time. The average values of the light tarp, from band 1 to 5, at New Pond 0 were 0.461, 0.481, 0.440, 0.427, 0.443, at New Pond 1 were 0.444, 0.459, 0.449, 0.435, 0.440, and at New Pond 3 were 0.450, 0.447, 0.433, 0.419, 0.426, respectively. The average values of the dark tarp, from band 1 to 5, at New Pond 0 were 0.122, 0.133, 0.125, 0.125, at New Pond 1 were 0.128, 0.125, 0.119, 0.118, and 0.121, and at New Pond 3 0.128, 0.125, 0.124, 0.119, 0.124, respectively.
  4. Where are the gaps in the data? What is missing?
    The 5-band orthoimage products have been cropped on the alongshore edges to exclude low-confidence areas. All orthoimages were created from interpolated digital elevation models in Metashape. GeoTIFFs are cloud-optimized.
  5. How consistent are the relationships among the observations, including topology?
    Six flights were flown in total for the field activity. Each flight produced images from the Altum-PT and Ricoh GRII. Two flights were flown per site: New Pond 0, New Pond 1, and New Pond 3. At each site an RGB orthoimage from the Ricoh imagery and a 5-band orthoimage and panchromatic orthoimage from the Altum-PT were created. The products may appear blurry or distorted near tall vegetation, 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 to the Ricoh RGB ortho products or Altum-PT panchromatic raster. The 5-band ortho product was calibrated in Metashape using a Micasense panel but the downwelling sensor was disabled after testing the difference in the final product. Output band values were also divided by 32768 to get the reflectance values for each band instead of digital numbers.

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. These data are not intended for navigational use.
  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 nine cloud-optimized GeoTIFF ortho products are deflate compressed and represent three sites from North Core Banks in North Carolina in October 2022.
  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?
  5. What hardware or software do I need in order to use the data set?
    Use of these files requires software capable of reading GeoTIFFs

Who wrote the metadata?

Dates:
Last modified: 28-Mar-2023
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)
This page is <https://cmgds.marine.usgs.gov/catalog/whcmsc/SB_data_release/DR_P99IV3FC/2022034FA_NCB_Orthos_meta.faq.html>
Generated by mp version 2.9.51 on Tue Mar 28 17:25:49 2023