Optical validation data were collected using the Tethered Optical Assessment Device (TOAD), a sled equipped with underwater video and still camera and lights. These data are used to provide ground-truth validation for benthic habitat maps based on multibeam echosounder surveys. Camera sled deployments were conducted during the day. The duration of each tow varied but averaged about 20 minutes of bottom time at a given location. The camera sled was deployed from a pot-hauler, mounted on the starboard aft of the vessel. The camera sled was lowered slowly to the seafloor by paying out cable, and once close to the seafloor, an altitude of 1-2 m was maintained by making adjustments on the length of cable out, using a remote pot-hauler switch, which allowed the operator to monitor a live video feed of the seafloor during operations. A second operator monitored the live video feed, and recorded real-time scientific observations, as well as any comments upon the operation, on a paper logsheet.
Equipment Description: The TOAD sled consisted of a modified Phantom ROV body with a tail piece added for stability. It was equipped with a Deep Sea Power and Light Multi SeaCam 2060 color video camera, oriented approximately 45 degrees to the seafloor to provide a view of the seafloor as well as some view of upcoming obstacles. The sled was also fitted with a downward facing digital still camera (Ocean Imaging System DSC12000, consisting of Nikon D90 dSLR with Nikkor 20mm F/2.8 lens), and two 50 W DeepSea Power and Light LED lights (one to illuminate the video and one the still camera). Scaling of the digital still photographs was provided by a pair of Deep Sea Power and Light SeaLaster 100 parallel lasers, mounted 10 cm apart. The sled was also fitted with a Tritech PA200 altimeter, and an electronics bottle containing a compass, and depth sensor. Power to the sled, and video and data feed from the sled was conducted via a 16mm, 150 m long coaxial cable, connected to a topside control unit. An on-screen display unit was used to overlay time, date, depth and altitude onto the video footage.
Name & address of person collecting data: John Rooney NOAA IRC NMFS/PIFSC/CRED 1845 WASP Blvd., Building 176 Honolulu, HI 96818
Data Files: Video data were recorded to miniDV tapes, and then backed up to DVD. Still images were saved to the camera's SD card and then backed up to external hard drive. Hypack 2012 hydrographic software was used to record time, vessel GPS position, camera sled altitude and depth, and length of cable out (entered manually). During deployments instantaneous layback calculations were performed by Hypack, using these data, and including the measured xyz offset between the vessel GPS antenna and the pot-hauler.
File naming convention: Each tow is given a name consisting of a three-letter designator for the island area, followed by a two-digit year and a three-digit tow number, which increments by one for each new tow around that island. For example, during SB1216 (the 16th cruise in the calendar year 2012) the first tow was called TAU12001. For subsequent cruises in the same year, the tow numbers will increment by 100, so the first tow on the next cruise to Ta'u in 2012 will be tow number TAU12100. Video tape labels and paper log forms are also annotated with the tow name; if more than one tape is required for a tow, consecutive letters are added to the end of the tow number (TAU12100a, TAU12100b, TAU12100c...). Navigation files generated by Hypack Max follow the Hypack CHS filename format consisting of the year, the first two letters of the platform name, the Julian date, and the hour and minute in which the file was started, followed by the extension .raw. For example, a file begun at 1935 on Dec. 10, 2004 (Julian date 345) aboard the Carolinian would be 2004CA3451935.raw.
Time Correlation: All clocks were synchronized to UTC at the beginning of each day's operations. Two clocks were manually synchronized to GPS-derived times: the acquisition computer clock and the internal clock of the OSD-79 on-screen display unit.
Resource Description: Digital video and still imagery that is geo-referenced to navigation files.