Surface sediment grain size distributions derived from automated image processing of in situ seafloor images from the lower Columbia River, Washington and Oregon, 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?
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• Who wrote the metadata?

What does this data set describe?

1. How might this data set be cited?
   Stevens, Andrew W., Warrick, Jonathan A., Hatcher, Gerald A., Ferro, Peter Dal, Dartnell, Peter, Cohn, Nicholas, and Moritz, Hans R., 20230808, Surface sediment grain size distributions derived from automated image processing of in situ seafloor images from the lower Columbia River, Washington and Oregon, 2021: data release DOI:10.5066/10.5066/P92U1KPY, U.S. Geological Survey, Pacific Coastal and Marine Science Center, Santa Cruz, California.

   Online Links:

   • https://doi.org/10.5066/P92U1KPY

   This is part of the following larger work.
   Stevens, Andrew W., Hatcher, Gerald A., Ferro, Peter Dal, Dartnell, Peter, Warrick, Jonathan A., Cohn, Nicholas, and Moritz, Hans R., 2023, Digital seafloor images, sediment grain size, bathymetry, and water velocity data from the lower Columbia River, Washington and Oregon, 2021: data release DOI:10.5066/P92U1KPY, U.S. Geological Survey, Pacific Coastal and Marine Science Center, Santa Cruz, CA.

   Online Links:

   • https://doi.org/10.5066/P92U1KPY

   Other_Citation_Details:

   Suggested Citation: Suggested Citation: Stevens, A.W., Hatcher, G.A., Dal Ferro, P., Warrick, J.A., Cohn, N., and Moritz, H.R., 2023, Digital seafloor images, sediment grain size, bathymetry, and water velocity data from the lower Columbia River, Washington and Oregon, 2021: U.S. Geological Survey data release, https://doi.org/10.5066/P92U1KPY.

2. What geographic area does the data set cover?

   West_Bounding_Coordinate: -123.442574
   East_Bounding_Coordinate: -122.762951
   North_Bounding_Coordinate: 46.250242
   South_Bounding_Coordinate: 45.712673
   

3. What does it look like?

   dgs_data_overview.png (PNG)

   Maps showing locations of seafloor images colored by median sediment diameter (d50)

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

   Beginning_Date: 05-Jun-2021

   Ending_Date: 08-Jun-2021

   Currentness_Reference:

   ground condition at time data were collected

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

   Geospatial_Data_Presentation_Form: comma-delimited text
   

6. How does the data set represent geographic features?
   1. How are geographic features stored in the data set?
      This is a Point data set. It contains the following vector data types (SDTS terminology):
      • Point (1402)
   2. What coordinate system is used to represent geographic features?
      Horizontal positions are specified in geographic coordinates, that is, latitude and longitude. Latitudes are given to the nearest 0.000001. Longitudes are given to the nearest 0.000001. Latitude and longitude values are specified in Decimal degrees. The horizontal datum used is WGS_1984.
      The ellipsoid used is WGS_1984.
      The semi-major axis of the ellipsoid used is 6378137.0.
      The flattening of the ellipsoid used is 1/298.257223563.
      
7. How does the data set describe geographic features?

   Attribute Table

   Table containing attribute information associated with the dataset (Source: Producer defined)

   image_group

   Classification of group of images (Source: Producer defined)

   Value	Definition
   Calibration	Images used for image processing technique calibration
   Validation	Image used for image processing technique validation
   ldb	Image collected from Lower Dobelbower (ldb) site
   skm	Image collected from Skamokawa(skm) site
   slg	Image collected from Slaughters Bar (slg) site
   wlw	Image collected from Willow Bar (wlw) site

   image_filename

   Filename of image collected (Source: Producer defined) Unique identifier for the image assigned in the field.

   analysis_flag

   Flag to indicate if image was analyzed to estimate grain size distribution or was too coarse or too fine for analysis (Source: Producer defined)

   Value	Definition
   dgs	Image was analyzed to estimate grain size distribution
   coarse	Grains in image are too coarse for analysis of grain size distribution
   fine	Grains in image are too fine for analysis of grain size distribution

   datetime_utc

   Date and time of image collection in yyyy-mm-dd HH:MM:SS.FFF format (Source: producer defined)

   Range of values
   Minimum:	2021-06-05 16:31:45.780
   Maximum:	2021-06-08 19:12:46.990
   Units:	Dates in yyyy-mm-dd HH:MM:SS.FFF format

   longitude

   Longitude of image in decimal degrees, east. NaN=not a number, because no location of the sample is available. (Source: producer defined)

   Range of values
   Minimum:	-123.442574
   Maximum:	-122.762951
   Units:	decimal degrees

   latitude

   Latitude of image in decimal degrees, north. NaN=not a number, because no location of the sample is available. (Source: producer defined)

   Range of values
   Minimum:	45.712673
   Maximum:	46.250242
   Units:	decimal degrees

   pixel_size_mm

   Size of pixels in image in millimeters (Source: producer defined)

   Range of values
   Minimum:	0.00657
   Maximum:	0.00657
   Units:	millimeters

   max_scale

   Maximum scale input value used in wavelet analysis (Buscombe, 2013) of grain size distribution. NaN=not a number, because image was not analyzed for grain size distribution. (Source: producer defined)

   Range of values
   Minimum:	2.957
   Maximum:	20.902
   Units:	unitless

   x_fac

   Area-by-number to volume-by-number conversion used in wavelet analysis (Buscombe, 2013) of grain size distribution. NaN=not a number, because image was not analyzed for grain size distribution. (Source: producer defined)

   Range of values
   Minimum:	1.5
   Maximum:	1.5
   Units:	unitless

   0.0078_mm

   Fraction of sample with grain diameter in 0.0078 mm bin. NaN=not a number, because image was not analyzed for grain size distribution. (Source: producer defined)

   Range of values
   Minimum:	0.00
   Maximum:	1.00
   Units:	fraction

   0.0093_mm

   Fraction of sample with grain diameter in 0.0093 mm bin. NaN=not a number, because image was not analyzed for grain size distribution. (Source: producer defined)

   Range of values
   Minimum:	0.00
   Maximum:	1.00
   Units:	fraction

   0.0111_mm

   Fraction of sample with grain diameter in 0.0111 mm bin. NaN=not a number, because image was not analyzed for grain size distribution. (Source: producer defined)

   Range of values
   Minimum:	0.00
   Maximum:	1.00
   Units:	fraction

   0.0131_mm

   Fraction of sample with grain diameter in 0.0131 mm bin. NaN=not a number, because image was not analyzed for grain size distribution. (Source: producer defined)

   Range of values
   Minimum:	0.00
   Maximum:	1.00
   Units:	fraction

   0.0156_mm

   Fraction of sample with grain diameter in 0.0156 mm bin. NaN=not a number, because image was not analyzed for grain size distribution. (Source: producer defined)

   Range of values
   Minimum:	0.00
   Maximum:	1.00
   Units:	fraction

   0.0186_mm

   Fraction of sample with grain diameter in 0.0186 mm bin. NaN=not a number, because image was not analyzed for grain size distribution. (Source: producer defined)

   Range of values
   Minimum:	0.00
   Maximum:	1.00
   Units:	fraction

   0.0221_mm

   Fraction of sample with grain diameter in 0.0221 mm bin. NaN=not a number, because image was not analyzed for grain size distribution. (Source: producer defined)

   Range of values
   Minimum:	0.00
   Maximum:	1.00
   Units:	fraction

   0.0263_mm

   Fraction of sample with grain diameter in 0.0263 mm bin. NaN=not a number, because image was not analyzed for grain size distribution. (Source: producer defined)

   Range of values
   Minimum:	0.00
   Maximum:	1.00
   Units:	fraction

   0.0312_mm

   Fraction of sample with grain diameter in 0.0312 mm bin. NaN=not a number, because image was not analyzed for grain size distribution. (Source: producer defined)

   Range of values
   Minimum:	0.00
   Maximum:	1.00
   Units:	fraction

   0.0372_mm

   Fraction of sample with grain diameter in 0.0372 mm bin. NaN=not a number, because image was not analyzed for grain size distribution. (Source: producer defined)

   Range of values
   Minimum:	0.00
   Maximum:	1.00
   Units:	fraction

   0.0442_mm

   Fraction of sample with grain diameter in 0.0442 mm bin. NaN=not a number, because image was not analyzed for grain size distribution. (Source: producer defined)

   Range of values
   Minimum:	0.00
   Maximum:	1.00
   Units:	fraction

   0.0526_mm

   Fraction of sample with grain diameter in 0.0526 mm bin. NaN=not a number, because image was not analyzed for grain size distribution. (Source: producer defined)

   Range of values
   Minimum:	0.00
   Maximum:	1.00
   Units:	fraction

   0.0625_mm

   Fraction of sample with grain diameter in 0.0625 mm bin. NaN=not a number, because image was not analyzed for grain size distribution. (Source: producer defined)

   Range of values
   Minimum:	0.00
   Maximum:	1.00
   Units:	fraction

   0.0743_mm

   Fraction of sample with grain diameter in 0.0743 mm bin. NaN=not a number, because image was not analyzed for grain size distribution. (Source: producer defined)

   Range of values
   Minimum:	0.00
   Maximum:	1.00
   Units:	fraction

   0.0884_mm

   Fraction of sample with grain diameter in 0.0884 mm bin. NaN=not a number, because image was not analyzed for grain size distribution. (Source: producer defined)

   Range of values
   Minimum:	0.00
   Maximum:	1.00
   Units:	fraction

   0.1051_mm

   Fraction of sample with grain diameter in 0.1051 mm bin. NaN=not a number, because image was not analyzed for grain size distribution. (Source: producer defined)

   Range of values
   Minimum:	0.00
   Maximum:	1.00
   Units:	fraction

   0.1250_mm

   Fraction of sample with grain diameter in 0.1250 mm bin. NaN=not a number, because image was not analyzed for grain size distribution. (Source: producer defined)

   Range of values
   Minimum:	0.00
   Maximum:	1.00
   Units:	fraction

   0.1487_mm

   Fraction of sample with grain diameter in 0.1487 mm bin. NaN=not a number, because image was not analyzed for grain size distribution. (Source: producer defined)

   Range of values
   Minimum:	0.00
   Maximum:	1.00
   Units:	fraction

   0.1768_mm

   Fraction of sample with grain diameter in 0.1768 mm bin. NaN=not a number, because image was not analyzed for grain size distribution. (Source: producer defined)

   Range of values
   Minimum:	0.00
   Maximum:	1.00
   Units:	fraction

   0.2102_mm

   Fraction of sample with grain diameter in 0.2102 mm bin. NaN=not a number, because image was not analyzed for grain size distribution. (Source: producer defined)

   Range of values
   Minimum:	0.00
   Maximum:	1.00
   Units:	fraction

   0.2500_mm

   Fraction of sample with grain diameter in 0.2500 mm bin. NaN=not a number, because image was not analyzed for grain size distribution. (Source: producer defined)

   Range of values
   Minimum:	0.00
   Maximum:	1.00
   Units:	fraction

   0.2973_mm

   Fraction of sample with grain diameter in 0.2973 mm bin. NaN=not a number, because image was not analyzed for grain size distribution. (Source: producer defined)

   Range of values
   Minimum:	0.00
   Maximum:	1.00
   Units:	fraction

   0.3536_mm

   Fraction of sample with grain diameter in 0.3536 mm bin. NaN=not a number, because image was not analyzed for grain size distribution. (Source: producer defined)

   Range of values
   Minimum:	0.00
   Maximum:	1.00
   Units:	fraction

   0.4204_mm

   Fraction of sample with grain diameter in 0.4204 mm bin. NaN=not a number, because image was not analyzed for grain size distribution. (Source: producer defined)

   Range of values
   Minimum:	0.00
   Maximum:	1.00
   Units:	fraction

   0.5000_mm

   Fraction of sample with grain diameter in 0.5000 mm bin. NaN=not a number, because image was not analyzed for grain size distribution. (Source: producer defined)

   Range of values
   Minimum:	0.00
   Maximum:	1.00
   Units:	fraction

   0.5946_mm

   Fraction of sample with grain diameter in 0.5946 mm bin. NaN=not a number, because image was not analyzed for grain size distribution. (Source: producer defined)

   Range of values
   Minimum:	0.00
   Maximum:	1.00
   Units:	fraction

   0.7071_mm

   Fraction of sample with grain diameter in 0.7071 mm bin. NaN=not a number, because image was not analyzed for grain size distribution. (Source: producer defined)

   Range of values
   Minimum:	0.00
   Maximum:	1.00
   Units:	fraction

   0.8409_mm

   Fraction of sample with grain diameter in 0.8409 mm bin. NaN=not a number, because image was not analyzed for grain size distribution. (Source: producer defined)

   Range of values
   Minimum:	0.00
   Maximum:	1.00
   Units:	fraction

   1.0000_mm

   Fraction of sample with grain diameter in 1.0000 mm bin. NaN=not a number, because image was not analyzed for grain size distribution. (Source: producer defined)

   Range of values
   Minimum:	0.00
   Maximum:	1.00
   Units:	fraction

   1.1890_mm

   Fraction of sample with grain diameter in 1.1890 mm bin. NaN=not a number, because image was not analyzed for grain size distribution. (Source: producer defined)

   Range of values
   Minimum:	0.00
   Maximum:	1.00
   Units:	fraction

   1.4140_mm

   Fraction of sample with grain diameter in 1.4140 mm bin. NaN=not a number, because image was not analyzed for grain size distribution. (Source: producer defined)

   Range of values
   Minimum:	0.00
   Maximum:	1.00
   Units:	fraction

   1.6820_mm

   Fraction of sample with grain diameter in 1.6820 mm bin. NaN=not a number, because image was not analyzed for grain size distribution. (Source: producer defined)

   Range of values
   Minimum:	0.00
   Maximum:	1.00
   Units:	fraction

   2.0000_mm

   Fraction of sample with grain diameter in 2.0000 mm bin. NaN=not a number, because image was not analyzed for grain size distribution. (Source: producer defined)

   Range of values
   Minimum:	0.00
   Maximum:	1.00
   Units:	fraction

   2.3780_mm

   Fraction of sample with grain diameter in 2.3780 mm bin. NaN=not a number, because image was not analyzed for grain size distribution. (Source: producer defined)

   Range of values
   Minimum:	0.00
   Maximum:	1.00
   Units:	fraction

   2.8280_mm

   Fraction of sample with grain diameter in 2.8280 mm bin. NaN=not a number, because image was not analyzed for grain size distribution. (Source: producer defined)

   Range of values
   Minimum:	0.00
   Maximum:	1.00
   Units:	fraction

   3.3640_mm

   Fraction of sample with grain diameter in 3.3640 mm bin. NaN=not a number, because image was not analyzed for grain size distribution. (Source: producer defined)

   Range of values
   Minimum:	0.00
   Maximum:	1.00
   Units:	fraction

   4.0000_mm

   Fraction of sample with grain diameter in 4.0000 mm bin. NaN=not a number, because image was not analyzed for grain size distribution. (Source: producer defined)

   Range of values
   Minimum:	0.00
   Maximum:	1.00
   Units:	fraction

   4.7570_mm

   Fraction of sample with grain diameter in 4.7570 mm bin. NaN=not a number, because image was not analyzed for grain size distribution. (Source: producer defined)

   Range of values
   Minimum:	0.00
   Maximum:	1.00
   Units:	fraction

   5.6570_mm

   fraction of sample with grain diameter in 5.6570 mm bin. NaN=not a number, because image was not analyzed for grain size distribution. (Source: producer defined)

   Range of values
   Minimum:	0.00
   Maximum:	1.00
   Units:	fraction

   gs_mean

   Arithmetic measure of mean grain size. NaN=not a number, because image was not analyzed for grain size distribution. (Source: producer defined)

   Range of values
   Minimum:	0.211
   Maximum:	1.663
   Units:	millimeters

   gs_sorting

   Arithmetic measure of grain size sorting. NaN=not a number, because image was not analyzed for grain size distribution. (Source: producer defined)

   Range of values
   Minimum:	0.092
   Maximum:	0.732
   Units:	millimeters

   gs_skewness

   Arithmetic measure of grain size skewness. NaN=not a number, because image was not analyzed for grain size distribution. (Source: producer defined)

   Range of values
   Minimum:	-0.145
   Maximum:	0.537
   Units:	millimeters

   gs_kurtosis

   Arithmetic measure of grain size kurtosis. NaN=not a number, because image was not analyzed for grain size distribution. (Source: producer defined)

   Range of values
   Minimum:	1.721
   Maximum:	2.362
   Units:	millimeters

   d5_mm

   Grain diameter whereby 5 percent of the cumulative percent of grains are finer than. NaN=not a number, because image was not analyzed for grain size distribution. (Source: producer defined)

   Range of values
   Minimum:	0.068
   Maximum:	0.501
   Units:	millimeters

   d10_mm

   Grain diameter whereby 10 percent of the cumulative percent of grains are finer than. NaN=not a number, because image was not analyzed for grain size distribution. (Source: producer defined)

   Range of values
   Minimum:	0.091
   Maximum:	0.675
   Units:	millimeters

   d16_mm

   Grain diameter whereby 16 percent of the cumulative percent of grains are finer than. NaN=not a number, because image was not analyzed for grain size distribution. (Source: producer defined)

   Range of values
   Minimum:	0.111
   Maximum:	0.842
   Units:	millimeters

   d25_mm

   Grain diameter whereby 25 percent of the cumulative percent of grains are finer than. NaN=not a number, because image was not analyzed for grain size distribution. (Source: producer defined)

   Range of values
   Minimum:	0.136
   Maximum:	1.046
   Units:	millimeters

   d30_mm

   Grain diameter whereby 30 percent of the cumulative percent of grains are finer than. NaN=not a number, because image was not analyzed for grain size distribution. (Source: producer defined)

   Range of values
   Minimum:	0.149
   Maximum:	1.156
   Units:	millimeters

   d50_mm

   Grain diameter whereby 50 percent of the cumulative percent of grains are finer than. NaN=not a number, because image was not analyzed for grain size distribution. (Source: producer defined)

   Range of values
   Minimum:	0.197
   Maximum:	1.669
   Units:	millimeters

   d75_mm

   Grain diameter whereby 75 percent of the cumulative percent of grains are finer than. NaN=not a number, because image was not analyzed for grain size distribution. (Source: producer defined)

   Range of values
   Minimum:	0.281
   Maximum:	2.328
   Units:	millimeters

   d84_mm

   Grain diameter whereby 84 percent of the cumulative percent of grains are finer than. NaN=not a number, because image was not analyzed for grain size distribution. (Source: producer defined)

   Range of values
   Minimum:	0.320
   Maximum:	2.513
   Units:	millimeters

   d90_mm

   Grain diameter whereby 90 percent of the cumulative percent of grains are finer than. NaN=not a number, because image was not analyzed for grain size distribution. (Source: producer defined)

   Range of values
   Minimum:	0.347
   Maximum:	2.631
   Units:	millimeters

   d95_mm

   Grain diameter whereby 95 percent of the cumulative percent of grains are finer than. NaN=not a number, because image was not analyzed for grain size distribution. (Source: producer defined)

   Range of values
   Minimum:	0.382
   Maximum:	2.730
   Units:	millimeters

   Entity_and_Attribute_Overview: The first line of the csv file is a header line.
   Entity_and_Attribute_Detail_Citation: U.S. Geological Survey
   

Who produced the data set?

1. Who are the originators of the data set? (may include formal authors, digital compilers, and editors)
   • Andrew W. Stevens
   • Jonathan A. Warrick
   • Gerald A. Hatcher
   • Peter Dal Ferro
   • Peter Dartnell
   • Nicholas Cohn
   • Hans R. Moritz
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?

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: 08-Jun-2021 (process 1 of 5)

   High resolution spatial surveys were performed between June 5 and 8, 2021 to quantify surface sediment grain size distributions of mobile subaqueous dunes at four sites in the lower Columbia River, Washington and Oregon. At each site, digital images of the sediment surface were collected with an underwater camera system that was repeatedly lowered to the seabed along a series of 1 km-long transects oriented along the main navigation channel and spaced about 60 m apart. The camera consisted of a FLIR Blackfly BFS-PGE-50S5 camera and 50 mm lens in a waterproof housing that resulted in a field of view of approximately 17 mm and a resolution of 0.00657 mm per pixel when the housing window was flush with the sediment surface. An ethernet cable between the survey vessel and camera provided power to the camera and allowed for real-time viewing of the seafloor imagery on a computer during acquisition. The locations of each seafloor image collected were determined using an Applanix POSMV Wavemaster global navigation satellite system receiver operating in DGNSS mode.

   Date: 13-Dec-2022 (process 2 of 5)

   Imagery were inspected to remove images that were not suitable for analysis, including blurry images and replicate images. Clear images of the seabed were subjectively classified into three groups including those that were suitable for automated grain size analysis, those that were too coarse (too few grains in the image), and those that were too fine (individual grains not visible) for analysis. The images that were too coarse or too fine for detailed quantitative analysis were retained for the qualitative information contained.

   Date: 20-Apr-2023 (process 3 of 5)

   The sediment grain size distributions of each image that were classified as suitable for image analysis were estimated using a combination of established automated image processing techniques (Buscombe, 2013, Rubin, 2004). Initial tests of the wavelet-based technique described in Buscombe (2013) suggested that the user-specified maximum scale, or maximum grain size that is considered in the analysis, was dependent on the size of grains in the images. An automated technique to specify an appropriate maximum scale for input in the wavelet analysis was established in the following manner. First, the grain size distributions of 15 calibration images were established by manually measuring the long and short axis of 100 grains in the images following methods described in Warrick and others (2009). Second, the wavelet analysis was applied using a range of maximum scale values for each calibration image and the optimal maximum scales were defined based on the RMS error between the measured and estimated quantiles describing the grain size distributions. Third, the autocorrelation coefficients of each image were computed according to Rubin (2004). The optimal maximum scale established for each calibration image was related to the lag distance corresponding to an autocorrelation coefficient of 0.65 using an exponential fit. Finally, the maximum scales of objective images were specified for the wavelet analysis based on the exponential curve.

   Date: 22-Apr-2023 (process 4 of 5)

   The grain size distributions estimated from automated image processing techniques (Buscombe, 2013, Rubin, 2004) were tested for a set of 16 validation images (separate from the calibration images used to establish the autocorrelation-maximum scale relationship) with observed grain size distributions. The observed grain size distribution data was generated for each image by manually measuring the long and short axis of 100 grains in the images following methods described in Warrick and others (2009). Grain size statistics were calculated based on the average distribution of long and short axis grain size measurements. Root-mean-square error between estimated and measured quantiles of the cumulative size distributions (using a percent finer convention; d16, d25, d50, d75, d84, and d90) varied between 5 and 12 mm or between 6 and 23 percent when normalized by the mean measured quantile. Agreement between estimated and measured cumulative size distribution was poorest for the smallest size fractions, with estimated quantiles biased too low. Good agreement was achieved for the median estimated grain size (d50), with a total root-mean-square error of 0.04 mm (6 percent) for images with median measured diameters between 0.29 and 1.07 mm.

   Date: 03-May-2023 (process 5 of 5)

   The grain size distributions of all suitable images collected in the lower Columbia River were computed using automated image processing techniques (Buscombe, 2013, Rubin, 2004). The results of the image analysis for the calibration and validation images and each site sampled were compiled into a comma-separated text files for distribution.

3. What similar or related data should the user be aware of?
   Buscombe, Daniel, 2013, Transferable wavelet method for grain-size distribution from images of sediment surfaces and thin sections, and other natural granular patterns.

   Online Links:

   • https://doi.org/10.1111/sed.12049

   Other_Citation_Details:

   Buscombe, D., 2013, Transferable wavelet method for grain-size distribution from images of sediment surfaces and thin sections, and other natural granular patterns, Sedimentology, v. 160, pp. 1709-1732.

   Rubin, David M., 2004, A simple autocorrelation algorithm for determining grain size from digital images of sediment.

   Online Links:

   • https://doi.org/10.1306/052203740160

   Other_Citation_Details:

   Rubin, D.M., 2004, A simple autocorrelation algorithm for determining grain size from digital images of sediment, Journal of Sedimentary Research, v. 74, pp. 160-165.

   Warrick, Jonathan A., Rubin, David M., Ruggiero, Peter, Harney, Jodi N., Draut, Amy E., and Buscombe, Daniel, 2009, Cobble cam: grain-size measurements of sand to boulder from digital photographs and autocorrelation analyses.

   Online Links:

   • https://doi.org/10.1002/esp.1877

   Other_Citation_Details:

   Warrick, J.A., Rubin, D.M., Ruggier, P., Harney, J.N., Draut, A.E., and Buscombe, D., 2009, Cobble cam: grain-size measurements of sand to boulder from digital photographs and autocorrelation analyses, Earth Surface Processes and Landforms, v. 34, pp. 1811-1821.

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

1. How well have the observations been checked?
   The grain size distributions estimated from automated image processing techniques (Buscombe, 2013, Rubin, 2004) were tested for a set of 16 images with observed grain size distributions. The observed grain size distribution data was generated for each image by manually measuring the long and short axis of 100 grains in the images following methods described in Warrick and others (2009). Grain size statistics were calculated based on the average distribution of long and short axis grain size measurements. Root-mean-square error between estimated and measured quantiles of the cumulative size distributions (using a percent finer convention; d16, d25, d50, d75, d84, and d90) varied between 5 and 12 mm or between 6 and 23 percent when normalized by the mean measured quantile. Agreement between estimated and measured cumulative size distribution was poorest for the smallest size fractions, with estimated quantiles biased too low. Good agreement was achieved for the median estimated grain size (d50), with a total root-mean-square error of 0.04 mm (6 percent) for images with median measured diameters between 0.29 and 1.07 mm.
2. How accurate are the geographic locations?
   The locations of each seafloor image collected were determined using an Applanix POSMV Wavemaster operating in DGNSS mode. Manufacturer reported accuracy of the horizontal positions while operating in DGNSS mode is between 0.5 and 2 m depending on the quality of the DGNSS corrections received (https://www.applanix.com/downloads/products/specs/posmv/POS-MV-WaveMaster-II.pdf). Additional uncertainty in the horizontal positions of the images due to instrument layback, or non-vertical wire angle between surface vessel and camera at the seafloor, is unknown but assumed to be minimal because of the weight of the camera and slow speed of the vessel relative to the ambient currents during image acquisition.
3. How accurate are the heights or depths?
   
4. Where are the gaps in the data? What is missing?
   Dataset is considered complete for the information presented, as described in the abstract. 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?
   No formal logical accuracy tests were conducted.

How can someone get a copy of the data set?

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

   2885 Mission Street

   Santa Cruz, CA
   

   1-831-427-4747 (voice)

   pcmsc_data@usgs.gov
2. What's the catalog number I need to order this data set? These data are available in csv format accompanied by CSDGM FGDC-compliant metadata.
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.
4. How can I download or order the data?
   • Availability in digital form:

     Data format:	csv table containing grain size distributions of images collected for calibration and validation of the image processing technique. in format comma-delimited text (version MATLAB Version: 9.13.0.2080170 (R2022b)) Size: 0.013
     Network links:	https://doi.org/10.5066/P92U1KPY

     Data format:	csv table containing grain size distributions of images collected from the Lower Dobelbower (ldb) site. in format comma-delimited text (version MATLAB Version: 9.13.0.2080170 (R2022b)) Size: 0.126
     Network links:	https://doi.org/10.5066/P92U1KPY

     Data format:	csv table containing grain size distributions of images collected from the Skamokawa (skm) site. in format comma-delimited text (version MATLAB Version: 9.13.0.2080170 (R2022b)) Size: 0.131
     Network links:	https://doi.org/10.5066/P92U1KPY

     Data format:	csv table containing grain size distributions of images collected from the Slaughters Bar (slg) site. in format comma-delimited text (version MATLAB Version: 9.13.0.2080170 (R2022b)) Size: 0.093
     Network links:	https://doi.org/10.5066/P92U1KPY

     Data format:	csv table containing grain size distributions of images collected from the Willow Bar (wlw) site. in format comma-delimited text (version MATLAB Version: 9.13.0.2080170 (R2022b)) Size: 0.157
     Network links:	https://doi.org/10.5066/P92U1KPY

   • Cost to order the data: None.

Who wrote the metadata?

Dates:

Last modified: 08-Aug-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)