How To Measure a Shark (Safely)
by brian lam
Measuring a shark. You could do it by catching one, and holding up a tape measure from its fin to its head, without harming it or yourself. Or you could use a camera rig.
This is what Dr Mark Meekan and Gabriel Vianna are doing in the shark sanctuary at Palau: Using two cameras and the geometry between them to measure the sharks. The technique, which has been described before in a 2009 paper entitled A Review of Underwater Stereo-Image Measurement For marine Biology and Ecology Applications, seems like the way to go.