USGS CoastCam at Waiakāne, Moloka'i, Hawai'i: 2018 Intrinsic and Extrinsic Calibration Data

The CoastCam was used to take IO photos. This involves slightly tilting a printed checkerboard with 30-millimeter (mm) squares in various parts of the cameras field of view. An example image can be found in MolokaiHI_c2_20180626_calibrationIOEO_exampleImagery.zip. There are a total of 72 IO images (MolokaiHI_c2_20180625_IO.zip) of which 62 were used for the intrinsic calibration. The 62 images were used in step A in the Camera Calibration procedures outlined in Bruder and Brodie (2020). The resultant parameters are stored in a YAML file located in MolokaiHI_c2_20180625_IO.zip. Image file naming format follows “MolokaiHI_c2_20180625_###”, 2018-06-25 is the date that the images were taken (YYYYMMDD format) and #### is the original unique ID from the camera.

Extrinsic orientation (EO) calibration ground control points (GCPs) were surveyed with a Trimble R7 survey-grade dual-frequency GNSS receiver set to record raw GNSS observables in Post-Processed Kinematic (PPK) mode. To place the photos taken by the CoastCam into real world coordinates and to rectify them into a planar view, objects within the field of view of the camera must be located. Multiple round targets painted white and black in opposite quadrants were put into the camera field of view to be visible by the CoastCam. One GNSS receiver was placed on a fixed-height survey rod and set to record observations for one minute at each ground control point at the center of each target (between black and white). A second GNSS receiver, serving as a base station, was placed on a fixed-height rod and placed on a temporary benchmark (MK02) approximately 1 kilometer from the survey area. The base receiver was programmed to record raw GNSS observations during survey operations. Reference coordinates for MK02 were established using the mean position derived from four static GNSS occupations with durations greater than 4 hours each submitted to the National Geodetic Survey Online Positioning User Service (NGS OPUS). These data were then used to post-process the GNSS measurements using the Trimble Business Center ver. 4.30 software package. The CoastCam took pictures of the position of each target within the camera view (raw JPEG image). The CSV file was used to hand label the raw images to generate annotated images so that the targets could be labeled correctly in Step B of the Camera Calibration steps in Bruder and Brodie (2020). The pixel coordinates of each GCP within the raw images, solved in Step B of Bruder and Brodie (2020), the GNSS positions from the CSV files, and the IO parameters in the IO YAML file were used in Step C of the Camera Calibration steps in Bruder and Brodie (2020) to solve for the EO parameters. The resultant parameters for the EO calibration are stored in a YAML file located in “MolokaiHI_c2_20180626_EO.zip”.

All intrinsic calibration images were given additional information required by the USGS to the exchangeable image file format (EXIF) and other imagery headers using PyExifTool Python library (https://pypi.org/project/PyExifTool/, version: 0.5.5). All intrinsic photos were given EXIF header information in the directory with all the photos by assigning all the tags in a Python dictionary object to each photo using PyExifTool. The following describes the Python dictionary object with each entry in the dictionary being a tag-value pair: tags = { 'Copyright': 'Public Domain', 'CopyrightNotice': 'Public Domain - please credit U.S. Geological Survey', 'Artist': 'USGS SPCMSC', 'Make': 'FLIR','Model': 'BFLY-PGE-50S5C-C','UserComment': ‘The following nested dictionary contains the cameras intrinsic and extrinsic calibration parameters. Intrinsic camera parameters use the Brown distortion model (Brown, D.C., 1971. "Close-Range Camera Calibration." Photogrammetric Engineering), using the Camera Calibration Toolbox for Matlab by Jean-Yves Bouguet (https://doi.org/10.22002/D1.20164). Extrinsic calibration parameters were computed using the CIRN Quantitative Coastal Imaging Toolbox (Bruder, B. L. and Brodie, K. L., 2020, "CIRN Quantitative Coastal Imaging Toolbox.", SoftwareX 12 (10052), https://doi.org/10.1016/j.softx.2020.100582.)’, 'GPSLatitude': '21.09305', 'GPSLongitude': '-157.15463', 'GPSMapDatum': 'EPSG:6321 (NAD83_National_Spatial_Reference_System_PA11)', 'GPSLatitudeRef': 'N', 'GPSLongitudeRef': 'W', 'GPSDateStamp': '2018-06-25', 'Credit': 'U.S. Geological Survey', 'Contact': 'gs-g-spcmsc_data_inquiries@usgs.gov', 'UsageTerms': "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 for other purposes, nor on all computer systems, nor shall the act of distribution constitute any such warranty", 'AttributionURL': 'https://doi.org/10.5066/P13XN6KM', 'ExternalMetadataLink': 'https://www1.usgs.gov/pir/api/identifiers/USGS:b3225ab5-26f8-4bf3-a14b-fa17e150914b', 'Contributor': 'Shawn R. Harrison, Mark L. Buckley, Joshua Logan, Andrew W.M. Pomeroy, Justin J. Birchler, Margaret L. Palmsten, Eric Swanson, Emily L. Johnson', 'XMP-photoshop:Credit': 'U.S. Geological Survey', 'iptcCore:CreatorWorkEmail': 'gs-g-spcmsc_data_inquiries@usgs.gov','Rights': 'Public Domain', 'Keywords' : "Waiakāne, Moloka'i, Hawai'i, CoastCam, USGS, intrinsic calibration, snapshot, remote sensing, ground control point", 'ImageDescription': 'This image was captured from a stationary mounted camera at Waiakāne, Moloka'i, Hawai'i. Field Activity Number: 2018-617-FA (https://cmgds.marine.usgs.gov/fan_info.php?fan=2018-617-FA)', 'Description': 'This image was captured from a stationary mounted camera at Waiakāne, Moloka'i, Hawai'i. Field Activity Number: 2018-617-FA (https://cmgds.marine.usgs.gov/fan_info.php?fan=2018-617-FA)'}. If there were errors generating keywords with the Python script, additional keywords were added to the imagery headers for all of the IO images using the following command: 'exiftool -sep ", " -iptc:keywords="Waiakāne, Moloka'i, Hawai'i, CoastCam, USGS, intrinsic calibration" *.jpg'. The UserComment EXIF metadata field was used to store the camera intrinsics and extrinsics in the image metadata. The UserComment has a nested dictionary structure. The highest-level dictionary contains two nested dictionaries as well as a note explaining the structure of the UserComment field. One nested dictionary contains the actual intrinsic and extrinsic data variables. The other nested dictionary contains text descriptions for each of the variables in the dictionary of data variables. To read out the imagery header information to a CSV file the command is: 'exiftool -csv *.jpg > allheaders.csv'. Specific tags may be specified with this command, if preferred.

All extrinsic calibration ground control point images were given additional information required by the USGS to the exchangeable image file format (EXIF) and other imagery headers using PyExifTool Python library (https://pypi.org/project/PyExifTool/, version: 0.5.5). All extrinsic photos were given EXIF header information in the directory with all the photos by assigning all the tags in a Python dictionary object to each photo using PyExifTool. The following describes the Python dictionary object with each entry in the dictionary being a tag-value pair: tags = { 'Copyright': 'Public Domain', 'CopyrightNotice': 'Public Domain - please credit U.S. Geological Survey', 'Artist': 'USGS SPCMSC', 'Make': 'FLIR','Model': 'BFLY-PGE-50S5C-C','UserComment': ‘The following nested dictionary contains the cameras intrinsic and extrinsic calibration parameters. Intrinsic camera parameters use the Brown distortion model (Brown, D.C., 1971. "Close-Range Camera Calibration." Photogrammetric Engineering), using the Camera Calibration Toolbox for Matlab by Jean-Yves Bouguet (https://doi.org/10.22002/D1.20164). Extrinsic calibration parameters were computed using the CIRN Quantitative Coastal Imaging Toolbox (Bruder, B. L. and Brodie, K. L., 2020, "CIRN Quantitative Coastal Imaging Toolbox.", SoftwareX 12 (10052), https://doi.org/10.1016/j.softx.2020.100582.)’, 'GPSLatitude': '21.09305', 'GPSLongitude': '-157.15463', 'GPSMapDatum': 'EPSG:6321 (NAD83_National_Spatial_Reference_System_PA11)', 'GPSLatitudeRef': 'N', 'GPSLongitudeRef': 'W', 'Credit': 'U.S. Geological Survey', 'Contact': 'gs-g-spcmsc_data_inquiries@usgs.gov', 'UsageTerms': "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 for other purposes, nor on all computer systems, nor shall the act of distribution constitute any such warranty", 'AttributionURL': 'https://doi.org/10.5066/P13XN6KM', 'ExternalMetadataLink':'https://www1.usgs.gov/pir/api/identifiers/USGS:b3225ab5-26f8-4bf3-a14b-fa17e150914b', 'Contributor': 'Shawn R. Harrison, Mark L. Buckley, Joshua Logan, Andrew W.M. Pomeroy, Justin J. Birchler, Margaret L. Palmsten, Eric Swanson, Emily L. Johnson', 'XMP-photoshop:Credit': 'U.S. Geological Survey', 'iptcCore:CreatorWorkEmail': 'gs-g-spcmsc_data_inquiries@usgs.gov','Rights': 'Public Domain', 'Keywords' : "Waiakāne, Moloka'i, Hawai'i, CoastCam, USGS, intrinsic calibration, snapshot, remote sensing, ground control point", 'ImageDescription': 'This image was captured from a stationary mounted camera at Waiakāne, Moloka'i, Hawai'i. Field Activity Number: 2018-617-FA (https://cmgds.marine.usgs.gov/fan_info.php?fan=2018-617-FA', 'Description': 'This image was captured from a stationary mounted camera at Waiakāne, Moloka'i, Hawai'i. Field Activity Number: 2018-617-FA (https://cmgds.marine.usgs.gov/fan_info.php?fan=2018-617-FA)'}. If there were errors generating keywords with the Python script, additional keywords were added to the imagery headers for all of the IO images using the following command: 'exiftool -sep ", " -iptc:keywords="Waiakāne, Moloka'i, Hawai'i, CoastCam, USGS, extrinsic calibration" *.jpg'. The only tag which can have a different value from image to image is GPSDateStamp. Depending on the date the photo was captured, the value in the GPSDatestamp tag changes. The UserComment EXIF metadata field was used to store the camera intrinsics and extrinsics in the image metadata. The UserComment has a nested dictionary structure. The highest-level dictionary contains two nested dictionaries as well as a note explaining the structure of the UserComment field. One nested dictionary contains the actual intrinsic and extrinsic data variables. The other nested dictionary contains text descriptions for each of the variables in the dictionary of data variables. To read out the imagery header information to a CSV file the command is: 'exiftool -csv *.jpg > allheaders.csv'. Specific tags may be specified with this command, if preferred.