Overlapping lakebed images and associated GNSS locations acquired near Dollar Point, Lake Tahoe, CA, March 2021

Underwater images were collected using a recently developed towed-surface vehicle with multiple downward-looking underwater cameras. The system is named the Structure-from-Motion (SfM) Quantitative Underwater Imaging Device with Five Cameras (SQUID-5). However, there were only 4 cameras operational for this collection due to a cable failure. Images were collected March 10th and 11th of 2021 by towing the SQUID-5 at a speed of approximately 3.0 knots along a series of adjacent survey lines in 2 to 4 meters of water in Lake Tahoe, CA. The survey location is approximately 650 meters south of Dollar Point in an area locally referred to as "Tahoe Reef" where the lakebed consists of interbedded lacustrine clay, silt, and sand that has a highly complex eroded surface. The cameras were synchronized with each other and with a survey-grade Global Navigation Satellite System (GNSS). Images were collected with nearly complete overlapping coverage of an area approximately 250 meters x 250 meters. The SQUID-5 system records images as TIFF (.tif) format to maintain the highest resolution and bit depth. The images are organized in zipped files grouped by survey line. 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. A separate text file is included which provides the GNSS antenna location at the time of each image capture with greater precision than is stored in the EXIF header due to decimal place limitations of the EXIF format. The images were collected to assess the accuracy, precision, and effectiveness of the new SQUID-5 camera platform to collect imagery for use in Structure-from-Motion (SfM) data processing of an area similar in size to an individual coral reef.