Shallow Along Track Reef Imaging System (sATRIS) Images – Dry Tortugas, Florida, 2011

High-resolution, geo-located images of the seafloor were captured July 13 to July 17, 2001 to characterize the seafloor and ground truth benthic habitat mapping efforts. The sATRIS was deployed from the USGS research vessel (R/V) Halimeda, running at a nominal speed of 2 knots and following pre-determined survey tracklines. GPS data were simultaneously collected at a fixed land-based location (24 37 46.70015 N, 82 52 22.29828 W) and on the R/V Halimeda during image and bathymetry acquisition using Ashtech Z-Xtreme GPS receivers. In this study, sATRIS images were collected at a rate of 3 hertz (Hz) along all tracks except track3, track13, and track 14 which were collected at a rate of 2 hertz (Hz), the single-beam depth soundings at 10 Hz, and the GPS data at 1 Hz. The GPS data were differentially corrected using GrafNav Version 8.40.5121, converted to the North American Datum of 1983 (2011) and the North American Vertical Datum of 1988 (using the GEOID12A model), and have sub-decimeter accuracy. Please note that these data are not suitable for navigational use, nor for determining absolute elevation measurements.

Water depths were computed for each sATRIS image with valid, differentially-corrected GPS and depth-sounder data using USGS-developed software. Not all images have valid GPS and/or sounder data. These images could not be differentially-corrected, and no water depths were computed for them, so they were excluded from this data release. All the data collected during this survey are stored on hard drives and archived at the U.S. Geological Survey office in St. Petersburg, Florida.

Raw sATRIS images exhibit barrel distortion due to the wide-angle camera lens. The images in this data release were corrected using an in-house image de-warping algorithm (Zawada, 2003).

Additional EXIF header information was added to the images using ExifTool by Phil Harvey (https://www.sno.phy.queensu.ca/~phil/exiftool/). A Java program was developed by USGS staff to make the EXIF header editing process faster and more automated. The tags populated in the headers are: Caption, Artist, Credit, Copyright, CopyrightNotice, Comment, Keywords, Contact, Caption-Abstract, GPSLatitude, GPSLatitudeRef, GPSLongitude, GPSLongitudeRef, GPSAltitude, GPSAltitudeRef, SubjectDistance, GPSTimeStamp, GPSDateStamp.

A Java program was developed to extract only the images that were both used for the habitat classification, and contained valid GPS and depth data. This subset of images is all that is available in this data release.

Added keywords section with USGS persistent identifier as theme keyword.