Whale spotting via IR

Whales are difficult to spot because they spend most of their life under water. And even when they surface to breathe, spouting a column of air and water vapor that rises from 1 to 10 m, only a portion of their body can be seen.

Now, a specially designed thermal imaging camera from Rheinmetall Defence Electronics GmbH of Bremen is using the heat generated by the spout to “see” the whale. The system is being tested on the research vessel Polarstern by Oceanic Acoustics, a research group at Alfred Wegener Institute that initiated the Marine Mammal Perimeter Surveillance project in early 2009.

Two humpback whales visit the Polarstern during one of its recent expeditions. Courtesy of Alfred Wegener Institute.

Dubbed First Navy, the camera overcomes the challenge of obtaining 360° visibility and compensates for the ship’s constant movement. And because the spout is visible for only a few seconds – and potentially from a great distance – high-resolution lenses similar to those used in animal photography are employed.

Installed in the ship’s crow’s nest at a height of approximately 28 m, the system sits on a stabilized platform so that the upper edge of the image is always aligned with the horizon, and the surrounding water surface is always in view. It generates five thermographic all-round images per second with a resolution of 7200 × 563 pixels of approximately 4 megapixels each, producing about 1 TB of data each day.

The hardware, however, is only half the story.

Dr. Olaf Boebel, head of the project, said that the group is developing software to search “the stream of pictures for whale spout in real time.” Its aim is to generate information about the direction and distance of a whale sighting together with video sequences so that a ship’s command can view it in real time.

Once tests are completed, the camera could help ships avoid collisions with whales and help users of hydroacoustic instruments take evasive action to avoid interference with marine mammals or interrupt seismic measurements. It also could directly support projects studying whale populations and migratory patterns in the scarcely researched Antarctic regions.

A thermal imager installed on the Polarstern’s crow’s nest at a height of approximately 28 m scans the ocean for surfacing whales. The sensor head (green) sits on a highly stabilized platform (white basis) and rotates at 5 rps. Courtesy of Lars Kindermann, Alfred Wegener Institute.

Other applications for the thermographic imager are ship security, including avoiding collisions with small icebergs – or growlers – and sea ice research. Being able to measure ice coverage at small scales is of interest to researchers, especially to those studying that of the diminishing Arctic, which often is seen as an indicator of the degree of climate change.