IN THIS ISSUE

NOTICE BOARD

Whale Shark Sightings 
 Jan - Mar 2008

In-water Sightings
5 Reported sighting
2 in-water encounter
0 shark identified
0 shark sexed
Note: this is not whale shark season and no monitoring trips were run

Whale Shark Internships 

There are still two whale shark internships available for the coming season (see Sagren 5.4), interested parties should us.

 SPOT! A 3-Dimensional Whale Shark Image Tool

EcOcean have just announced the launch of a new image manipulation tool aimed at assisting with matching whale shark photo-ID images. The pattern recognition programs used in whale shark image matching are based on mathematical algorithms (Modified Groth and I³S) and assume a flat, two-dimensional surface when analyzing the relationships between spots, while whale sharks are in fact quite cylindrical. 

Screen grab from the SPOT! program showing a skewed image aligned onto the 3D reference form. Image courtesy MCSS

Both of the algorithms have some tolerance for images taken at an angle from the perpendicular and will cope with these; however, both programs quickly degrade in their ability to match identical patterns as the angles between them gets larger. 

Spot! allows the user to map a skewed 2D image to a 3D whale shark model and obtain a properly oriented left- or right-side pattern for use with the Modified Groth and I³S algorithms. This should allow a number of oblique images to be used in the matching programs.

An example of an oblique whale shark photo and the image turned and corrected with SPOT! and then run through the EcOcean recognition programme. Images courtesy EcOcean

The SPOT! perspective correction has been used in the ECOCEAN Library to match images taken from very extreme angles to previously tagged whale sharks and is likely to become another useful tool for whale shark research. The program is available for free download from the EcOcean web site.