Overlapping lakebed images collected near Dollar Point, Lake Tahoe, CA, March 10 and 11, 2021

Metadata also available as - [Outline] - [Parseable text] - [XML]

Frequently anticipated questions:

What does this data set describe?

Title:
Overlapping lakebed images collected near Dollar Point, Lake Tahoe, CA, March 10 and 11, 2021
Abstract:
Underwater images were collected near Dollar Point, Lake Tahoe, CA, using a recently developed towed-surface vehicle with multiple downward-looking underwater cameras. The images are organized in zipped files grouped by survey line. The SQUID-5 system records images as TIFF (.tif) format to maintain the highest resolution and bit depth. Each image includes EXIF metadata, containing GNSS date, time, and latitude and longitude of the GNSS antenna mounted on the towed surface vehicle, copyright, keywords, and other fields.
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=2021-607-FA Any use of trade, product, or firm names is for descriptive purposes only and does not imply endorsement by the U.S. Government.
  1. How might this data set be cited?
    Hatcher, Gerald A., Warrick, Jonathan A., Kranenburg, Christine J., and Ferro, Peter Dal, 20210930, Overlapping lakebed images collected near Dollar Point, Lake Tahoe, CA, March 10 and 11, 2021: data release DOI:10.5066/P9V44ZYS, U.S. Geological Survey - Pacific Coastal and Marine Science Center, Santa Cruz, California.

    Online Links:

    This is part of the following larger work.

    Hatcher, Gerald A., Warrick, Jonathan A., Kranenburg, Christine J., and Ferro, Peter Dal, 2021, Overlapping lakebed images and associated GNSS locations acquired near Dollar Point, Lake Tahoe, CA, March 2021: data release DOI:10.5066/P9V44ZYS, U.S. Geological Survey - Pacific Coastal and Marine Science Center, Santa Cruz, California.

    Online Links:

  2. What geographic area does the data set cover?
    West_Bounding_Coordinate: -120.10407
    East_Bounding_Coordinate: -120.09931
    North_Bounding_Coordinate: 39.18048
    South_Bounding_Coordinate: 39.17705
  3. What does it look like?
    CAM13-20210310203823_000-1.jpg (JPG)
    Example of underwater photo from one of the cameras.
  4. Does the data set describe conditions during a particular time period?
    Beginning_Date: 10-Mar-2021
    Ending_Date: 11-Mar-2021
    Currentness_Reference:
    ground condition
  5. What is the general form of this data set?
    Geospatial_Data_Presentation_Form: TIFF
  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?
      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 North American Datum of 1983 (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 1/298.257223563.
  7. How does the data set describe geographic features?
    Entity_and_Attribute_Overview:
    SQUID-5 Imagery (Line##.zip) - Individual images are available in TIFF format and are contained within zip files and organized by survey lines (##) See Process_Step/IMAGE ACQUISITION for naming convention of individual images.
    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)
    • Gerald A. Hatcher
    • Jonathan A. Warrick
    • Christine J. Kranenburg
    • Peter Dal Ferro
  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

    831-460-4747 (voice)
    pcmsc_data@usgs.gov

Why was the data set created?

The imagery and associated location data were collected to assess the accuracy, precision, and effectiveness of the new SQUID-5 camera platform to collect contiguous imagery for use in Structure-from-Motion (SfM) data processing of an area similar in size to an individual coral reef.

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: 11-Mar-2021 (process 1 of 4)
    IMAGE ACQUISITION Images were collected in tiff (.tif) format in synchronized quartets by the SQUID-5 system while towed at a speed of approximately 3 knots behind the UC Davis R/V John LaConte during USGS field activity 2021-607-FA. Image collection frequency was 1 Hz, and a GNSS position was recorded for each collection instant. Image gain settings were adjusted as needed depending on water depth and lighting conditions. Aperture and shutter speed were consistent for each group of images at a study site. Image files were named programmatically with the last two digits of the camera's serial number, a 14-digit UTC datetime value formatted as yyyymmddhhmmss, thousandths of seconds, and the sequential image number for that camera. For example, 'CAM13-20210310203823_000-1.tif' indicates camera 13, March 10, 2021, 20:38:23.000 (UTC), collection event number 1 of the survey line. Person who carried out this activity:
    U.S. Geological Survey
    Attn: Gerald Hatcher
    Ocean Engineer
    2831 Mission Street
    Santa Cruz, CA

    831-460-7524 (voice)
    831-421-9209 (FAX)
    ghatcher@usgs.gov
    Date: 04-Aug-2021 (process 2 of 4)
    SQUID-5 NAVIGATION PROCESSING Raw GNSS data received by the antenna mounted atop the SQUID-5 were recorded at 10 Hz by a dual-frequency survey-grade GNSS receiver, which was post-processed and differentially corrected against the Kings Beach, CA, (P150) continuously operating reference station (CORS) in Novatel's GrafNav software (v. 8.80.2720; https://novatel.com/products/waypoint-post-processing-software/grafnav) to produce 1-Hz SQUID-5 trajectories. The SQUID-5 trajectories, in combination with precisely recorded image capture event times, are used to generate SQUID-5 GNSS antenna positions at the moment of each image capture in the accompanying navigation file (2021_607_FA_Image_Locations.txt). The positions in the SQUID-5 navigation file represent the position of the SQUID-5 GNSS antenna reference point (ARP), not the position of the cameras or features photographed. To determine actual image positions, photogrammetric software such as Agisoft Metashape can be used to apply the lever arm offsets (in the camera frame of reference) from the GNSS antenna reference point to the camera lens. Using this method the following values for each camera were calculated for x,y,z in units of meters. Camera 13, 0.03536 m(x), -0.00407 m(y), 0.84721 m(z); Camera 30, -0.29259 m(x), -0.07655 m(y), 0.93223 m(z); Camera 39, 0.27623 m(x), -0.01498 m(y), 0.93657 m(z); Camera 82, -0.01679 m(x), -0.60744 m(y), 0.75020 m(z). Person who carried out this activity:
    Christine J. Kranenburg
    U.S. Geological Survey, St. Petersburg Coastal and Marine Science Center
    Cartographer
    600 4th Street South
    St. Petersburg, FL
    USA

    727-502-8000 (voice)
    ckranenburg@usgs.gov
    Date: 26-Aug-2021 (process 3 of 4)
    IMAGE EXIF cSORTING Georeferencing, copyright, and other relevant information was added to the EXIF header of each photo using Phil Harvey's ExifTool (v. 11.88; https://exiftool.org/). To extract the information from the image headers using ExifTool, the following command can be used (tested with ExifTool version 11.88): exiftool -csv -f -filename -GPSDateStamp -GPSTimeStamp -GPSLongitude -GPSLatitude -n -Artist -Credit -comment -keywords -Caption -Copyright -CopyrightNotice -Caption-Abstract -ImageDescription directoryname/*.tif > out.csv The -csv flag writes the information out in a comma-delimited format. The -n option formats the latitude and longitude as signed decimal degrees. Images are sorted by survey line number and stored within zip files to limit the file sizes. Person who carried out this activity:
    U.S. Geological Survey
    Attn: Gerald Hatcher
    Ocean Engineer
    2831 Mission Street
    Santa Cruz, CA

    831-460-7524 (voice)
    831-421-9209 (FAX)
    ghatcher@usgs.gov
    Date: 13-Oct-2021 (process 4 of 4)
    Performed minor edits to the metadata to correct typos. No data were changed Person who carried out this activity:
    U.S. Geological Survey
    Attn: Susan A. Cochran
    Geologist
    2885 Mission Street
    Santa Cruz, CA

    831-460-7545 (voice)
    scochran@usgs.gov
  3. What similar or related data should the user be aware of?
    Hatcher, Gerald A., Warrick, Jonathan A., Ritchie, Andrew C., Dailey, Evan T., Zawada, David G., Kranenburg, Christine, and Yates, Kimberly K., 2020, Accurate bathymetric maps from underwater digital imagery without ground control: Frontiers in Marine Science vol. 7.

    Online Links:

    Other_Citation_Details: article 525

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

  1. How well have the observations been checked?
    The accuracy of the position data is based on the accuracy of the post-processed GNSS navigation data, which produced a 1-Hz vehicle trajectory with an estimated 2-sigma accuracy of 10 cm horizontal and 15 cm vertical. Note that the positions in the image EXIF headers are GNSS antenna positions and are limited to six decimal places, whereas the positions in the accompanying navigation file (2021-607-FA_Image_Locations.txt) are accurate to ten decimal places and are therefore highly recommended for use in SfM processing to produce the highest quality derived products.
  2. How accurate are the geographic locations?
    Positions provided in the accompanying navigation file (2021-607-FA_Image_Locations.txt) have an estimated 2-sigma horizontal accuracy of 10 cm. The accuracy of the positions in the image EXIF headers are reduced due to field size limitations for storing latitude/longitude.
  3. How accurate are the heights or depths?
    Positions provided in the accompanying navigation file (2021-607-FA_Image_Locations.txt) have an estimated 2-sigma vertical accuracy of 15 cm.
  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?
    All data fall within expected ranges.

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:
USGS-authored or produced data and information are in the public domain from the U.S. Government and are freely redistributable with proper metadata and source attribution. Please recognize and acknowledge the U.S. Geological Survey as the originator of the dataset and in products derived from these data. This information is not intended for navigation purposes.
  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 TIFF format contained in zip files organized by survey line. The image files are named with the following convention: camera serial number, 14-digit UTC datetime value, thousandths of seconds, and sequential image number for specified camera. The TIFF image files contain EXIF metadata, including GNSS time and position data, and are included as an open-source format for preservation purposes.
  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: The .zip files contains images in tagged image file format (.tif) in format TIFF
      Network links: https://doi.org/10.5066/P9V44ZYS
    • Cost to order the data: none

Who wrote the metadata?

Dates:
Last modified: 13-Oct-2021
Metadata author:
U.S. Geological Survey, Pacific Coastal and Marine Science Center
Attn: PCMSC Science Data Coordinator
2885 Mission Street
Santa Cruz, CA

831-460-4747 (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/CMGDS_DR_tool/DR_P9V44ZYS/2021-607-FA_Raw_Imagery_metadata.faq.html>
Generated by mp version 2.9.50 on Thu Oct 14 14:47:20 2021