Deep ATRIS - An Auto-adjusting, Towed, Digital Imaging System

Configuration of Deep ATRIS

Maps of coral ecosystems are needed to support many conservation and management objectives, as well as research activities. Examples include ground-truthing aerial and satellite imagery, characterizing essential habitat, assessing changes, and monitoring the progress of restoration efforts. To address some of these needs, the U.S. Geological Survey developed the Along-Track Reef-Imaging System (ATRIS), a boat-based sensor package for mapping shallow-water benthic environments.

Deep ATRIS extends this functionality to depths of 27 m. The system is based on The Sea Sciences, Inc. Acrobat™ LTV-50, a light-weight, computer-controlled, towed vehicle that is capable of following a programmed diving profile. The vehicle is 81 cm long with a 63-cm wing span and can carry a wide variety of research instruments, including CTDs, fluorometers, transmissometers, and cameras. Deep ATRIS is currently equipped with a high-speed (20 frames/s) digital camera, custom-built light-emitting-diode lights, a compass, a 3-axis orientation sensor, and a nadir-looking altimeter.

Current configuration of Deep ATRIS. [Enlargement]

Specifications: Dimensions (LxWxH) 0.81 x 0.25 x 0.63 m      Wing span 1.2 m Weight (in air) 45 kg Operating Depth Range:        3 – 27 (m) Image size: 1,360 x 1,024 pixels Image capture: 1 - 20 images/s

The vehicle dynamically adjusts its altitude to maintain a fixed height above the seafloor. The camera has a 29° x 22° field-of-view and captures color images that are 1360 x 1024 pixels in size. GPS coordinates are recorded for each image. A gigabit ethernet connection enables the images to be displayed and archived in real time on the surface computer. Deep ATRIS has a maximum tow speed of 2.6 m/s.

Deployment of Deep ATRIS

Only a modest amount of support equipment is needed to deploy Deep ATRIS. Typically, we use a 25' Oceans Formula boat with a tow bar to keep the cable away from the outboard motor and a standard sailboat winch to aid cable retrieval. A portable Honda generator powers the system and the computers. [Enlargement]

Movies of Deep ATRIS

View: Cartoon Movie of Deep ATRIS in action. (File size: 2.3 MB, Duration 33 seconds)		View: Deep ATRIS Acquisition Movie (File Size: 42 MB, duration 34 seconds)
(Download latest version of FREE Apple QuickTime player)

Deep ATRIS: Example Image Mosaics

Spatial resolutions of better than 3 mm/pixel are common. In most instances, taxonomic identification is possible at least to the genus level. Given this degree of detail, coupled with the coincident bathymetric and location data, Deep ATRIS imagery is more than adequate for ground-truthing acoustic and lidar data, as well as classifying habitats. It can be used to estimate a number of ecological parameters, such as percent cover, organism abundance, and species richness.

A 4-image mosaic of barrell sponges and octocorals, covering a region approximately 2.4 m x 4.6 m in size. Water depth was 8.6 m and Deep ATRIS was 4.7 m. above the bottom. [Enlargement]

A 6-image mosaic of an area dominated by various octocorals, sponges, and the zoanthid Palythoa caribaeorum. A midnight parrotfish (Scarus coelestinus) is visible in the central portion of the mosaic. The areal coverage is approximately 5 m x 13 m. Water depth at the base of the ledge was 10.4 m and Deep ATRIS was 9.7 m above the bottom. [Enlargement]

Deep ATRIS: Animal Image Sequences

Given that fish and sea turtles are seemingly unfazed by its presence, there are likely fisheries applications for Deep ATRIS.

Grey Angelfish (Ponacanthus arcualus). Water depth was 8.8 m, and Deep ATRIS was 2.4 m above the bottom. Image resolution is 0.9 mm/pixel. [Enlargement]

Spadefish (Chaetodipterus faber) are in the foreground with several grunts (Haemulon sp.) hovering above a brain coral head (Diploria sp.) in the background. Water depth was 9.2 m, and Deep ATRIS was 2.35 m above the bottom. Image resolution is 0.9 mm/pixel. [Enlargement]

A Hawksbill turtle (Eretmochelys imbricata) resting on the sea-floor. Water depth was 9.2 m, and Deep ATRIS was 2.93 m above the bottom. Image resolution is 1.1 mm/pixel. [Enlargement]

Deep ATRIS: Contact Information

Dr. Dave Zawada - U.S. Geological Survey
600 4th Street South, St. Petersburg, Florida 33701
Phone: 727-803-8747 x3132
Email: (dzawada@usgs.gov)