Surface Area, Volume, and Projected Area of Japanese-Shorthorn Cattle Measured by Stereo Photogrammetry Using Non-metric Cameras.

Abstract

Three-dimensional measurement of five heads of Japanese-Shorthorn cattle was achieved using two non-metric cameras by stereo photogrammetry. The relationships between weight and surface area, volume, and projected area from side of the cattle were investigated. Surface area, volume, and projected area from side were exponentially related to weight. The exponential power was the greatest in volume. The ratio of surface area to projected area from side ranged from 3.1 at a weight of 600kg to 2.9 at 750kg. This means that surface area can be obtained by tripling the projected area from side using a single photograph. The exponential power of volume with weight was closer to that of a basal energy metabolic power of 0.75 than that of surface area with weight. This implies that basal energy metabolism is not proportional to surface area but to volume. The close relationship between projected area from side and weight can be applied to estimate the weight of cattle by image analysis.