Natural pattern analysis :

The pictures of wild individuals are analysed the same way as captive ones using the open access software I3S and Image J. The first step of image processing is to transform the back picture into a binary (black and white) result. This process is done through the use of  "ImageJ", we created a semi-automatic protocol which can be repeated by different analysts, keeping consistency in the treatment of each image. Once the black and white images are ready, we can use a photo-identification software, in this case I3S pattern+, to identify the individual and try to match it with other sighting in our database.

data analysis


Use of laser photogrammetry for indirect measurements:

Indirect measurements are made using the software ImageJ. The first step is to scale the pictures thanks to the known distance between our two laser dots. Once the pictures are scaled we can easily extract different measurements (total length, discal length...). Thanks to the discal length we know if the individual is mature (>90 cm) or not. Some sexual dimorphisms, visible from a back picture can allow us to determine the sex of the individual, like the spine length or the presence of horns (see pictures below). Indeed, for two individuals of the same total length (TL) but different sexes, the spine of the female will be around two times longer than the male.


croquis bull ray3