Digital photogrammetry and laser rangef inder techniques to measure African elephants

摘要

Photogrammetry can be used to measure the body dimensions of a variety of mammals. We developed a digital photogrammetry technique and used an infrared laser rangefinder to measure the shoulder heights of African elephants (Loxodonta africana). Measures of the height of objects of known size using digital photogrammetry were between 0.7% shorter to 0.6% taller than the real values. The rangefinder recorded values that ranged from 0.8% to 3.6% larger than the real height. When we applied digital photogrammetry to tame elephants, measured shoulder heights were 1.6% to 3.4% shorter than those recorded using a custom-made calliper. For these elephants, the rangefinder recorded shoulder heights that were 3.8 to 9.4% smaller than the real values. The digital photogrammetric technique described here is less time-consuming and as or more precise than other techniques used to measure African elephants.