As still and video cameras can be mounted to tow bodies in a variety of ways (Figure 7.1, Table 7.1), this field manual does not mandate specific gear types. Rather, it provides recommendations for future updates or replacement of existing platforms. It targets the suite of towed camera platforms currently being used to acquire quantitative imagery of benthic habitats in Australian waters, and seeks to standardise monitoring efforts by recommending standard operating procedures (SOPs) for survey planning, field acquisition and post-survey data processing, description, and storage for public accessibility (Figure 7.2).
The primary aim of this field manual is to establish a consistent approach to marine benthic sampling using towed camera systems that will facilitate statistically sound compilation between studies. Note that hybrid towed systems and other video-based monitoring platforms (e.g. dropped video cameras, or video and still cameras mounted on sleds or trawls) that are commonly used to gather qualitative sample data (e.g. general animal behaviour) fall outside the scope of this manual.
Figure 7.1: Types of towed camera systems deployed in Australian waters. a) MNFs Deep Towed Camera platform; b) and c) AIMS towed camera platform being deployed off RV Solander; d) towed camera platform being trialled by Geoscience Australia off RV Southern Surveyor; e) and f) Deakin University towed video system.
Table 7.1: Types of towed camera systems deployed in Australian waters and their main characteristics. Note this list is not comprehensive. See reviews on towed cameras and perspectives in visual imagining for information about gear deployed elsewhere in the world (Durden et al. 2016a).
| Towed Platform | AIMS Towvid | CSIRO - MNF Deep Towed Camera | CSIRO – MRITCO&A Deep Towed Camera | NSW DCCEEW | Deakin |
|---|---|---|---|---|---|
| Dimensions (W x H x L mm) |
500 x 500 x 600 | 1200 x 1300 x 2000 | 1200 x 1300 x 1700 | 1100 x 900 x 500 | 400 x 600 x 300 |
| Weight (kg) | 30 | 490 | 340 | 15 | 20 |
| Max depth (m) | 250 | 2500 | 2500 | 200 | 120 |
| Camera system (video) & orientation | Blue Robotics HD USB video forward facing camera Additional forward facing GoPro (optional) |
Canon C300 high definition video camera with a Canon EFS 10-18mm f4.5-5.6 lense at 45 deg. Hitachi – HV-D30P forward facing camera |
Canon ME20F-SH high definition video camera with a Zeiss Distagon 18mm f3.5 lense at 45 deg. | Forward looking GBO Technology 1080 IP video camera in central pressure housing (CSIRO) camera at 30 degrees through Fibre Optic Cable | SD video oblique facing Additional oblique facing STEREO HD GoPro with 400mm base bar |
| Camera system (stills) & orientation | 17MP downward stills | Canon 1DX stills camera with a Zeiss Distagon 18mm f3.5 lens set at 45 deg. | 2 x Canon 1DX MKII stereoscopic stills cameras with Zeiss Distagon 18mm f2.8 lens set at 45 deg. | Downward looking stills Canon EOS450D | 12MP downward stills with strobe |
| Illumination | Blue Robotics 1500 lumen subsea lights Kraken KR05 strobe synced to camera by LED trigger and optic slave cable |
4 x Deep Sea Power and Light – 3150 Sea Light Sphere | 4 x Deep Sea Power and Light – LSL-2000 LED Sealite for video 2 x Customized Quantum Qflash Trio for stills |
2 Keldan LUNA 8 CRI lamps | Video ray lights for oblique view and strobe for down facing imagery |
| Laser(s) | Downward stills x 3 | 2 x Laserex 10 mW (red) 16-laser array unit for stereo video calibration A pair of lasers with a known separation distance (10cm) is used as a reference for scaling objects and aligning video and stills in time. |
2 x Teledyne Bowtech Ocealaser-D-5 at 300mm spacing | A pair of 5mw green-light laser pointers (100 mm separation) for downward looking camera | |
| Sensors | Applied Acoustics Nexus Eastrak USBL | Pressure: Druck PMP 5074 IMU (pitch, roll and yaw) : Lord – 3DM-GX3-25 Altimeter : Kongsberg Mesotech – 1007D CTD : Seabird SBE 37 Position: Sonardyne USBL WMT |
Pressure: Digiquartz 9000-10K-10 IMU (pitch, roll and yaw) : Lord – 3DM-GX5-25 Altimeter : Datasonics PS900 CTD : Seabird SBE 37 Position: Sonardyne USBL WMT |
Pressure, Camera Temperature, Applanix POS MV providing 100 Hz Roll/Pitch/Yaw and positioning (G2 GNSS), sounder depth, camera angle from horizontal, USBL 1500 EvoLogics (tow fish) |
HOBO Pendant temperature/light data loggers (UA-002-08) recorded mean light (lum/ft²) and temperature (˚C) at ten-second intervals for the duration of each deployment |
| Suitable terrain | All, but steep inclines are best surveyed downslope; rugged terrain in low visibility is also risky. | The Deep Towed Camera can only be deployed on a downhill/flat gradient and travelling towards deeper/open water to mitigate against winch failures | The Deep Towed Camera can only be deployed on a downhill/flat gradient and travelling towards deeper/open water to mitigate against winch failures | All but relatively steep terrain – always planned downslope; usually <100m water depth, turbidity, wind waves and strong currents in nearshore limiting factor – small vessel ops | |
| Example Reference | (Nichol et al. 2013) | (Sherlock et al. 2016) | (Marouchos et al. 2017) | (Ingleton et al. 2018) | (Logan et al. 2017) |
Figure 7.2: Workflow for towed camera image acquisition and processing. Purple represents onboard methods, while blue represents post-survey methods.