By St\u00e9phanie Tremblay<\/p>\n
When we see a whale from shore, or even from a boat, it looks quite small. Even if it does not appear so big, a beluga can nevertheless measure up to 4.5 metres long! How can we go about calculating this length without touching the animal?<\/p>\n
By photogrammetry! A seemingly complicated word for a technique that at first glance is rather simple. First, scientists simultaneously place two lasers (observable 100 metres away in daylight) on their camera. The important thing is that the beams are sharp enough to be visible. They must also be green (not red, as we are accustomed to), for the simple reason that the human eye sees green better.<\/p>\n
With tools and a little dexterity, the photographer positions the lasers at a distance of 10\u00a0cm on a sort of L-shaped metal bracket. A bolt attached to the camera is used to change the vertical axis in order to take better aim. After a few adjustments, researchers are able to measure moving cetaceans.<\/p>\n
By knowing the distance between the points created by the lasers and by relying on various reference points (blowhole, dorsal fin, peduncle, etc.), researchers can ascertain the total length of the specimen or a part of its body (such as its dorsal fin, for example), even if they see only a small fraction of the animal’s body.<\/p>\n","protected":false},"excerpt":{"rendered":"
By St\u00e9phanie Tremblay When we see a whale from shore, or even from a boat, it looks quite small. Even if it does not appear so big, a beluga can nevertheless measure up to 4.5 metres long! How can we go about calculating this length without touching the animal? By photogrammetry! A seemingly complicated word […]<\/p>\n","protected":false},"author":15,"featured_media":39620,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"_acf_changed":false,"_monsterinsights_skip_tracking":false,"footnotes":""},"categories":[29],"tags":[413,1455,451,1456],"class_list":["post-49833","post","type-post","status-publish","format-standard","has-post-thumbnail","hentry","category-whale-qa","tag-echouage-en","tag-mesure-en","tag-photogrammetrie-en","tag-technique-scientifique-en"],"acf":[],"yoast_head":"\n