Animal Science Abstract
Shape measurements of live pigs using 3-D image capture
N. J. B. McFarlane1,A, J. Wu1, R. D. Tillett1, C. P. Schofield1, J. P. Siebert2 and X. Ju2
AE-mail: nigel.mcfarlane@SilsoeResearch.org.uk
11BBSRC Silsoe Research Institute, Wrest Park, Silsoe, Bedford MK45 4HS, UK
2Department of Computer Science, Boyd Orr Building, University of Glasgow, University Avenue, Glasgow G12 8QQ, UK
Abstract
A photogrammetric stereo imaging system was used to capture 3-D models of live pigs, and quantitative shape measurements were extracted from cross sections of the models. Stereo images were captured of 32 pigs, divided into high-lysine and low-lysine diet groups, and 3-D models were built from the images. Each pig was imaged once per week for 14 weeks. After slaughter, 10 of the pigs were dissected for muscle and fat measurements. A sequence of algorithms was applied to the 3-D models : differential geometry to reveal surface curvature features and detect the spine; manual landmark placement; fitting a curve to the spine; determining the vertical axis of the body; placing a slice plane across the abdomen close to the P2 position; extracting a cross section; and fitting a shape model to the cross section. Differential geometry revealed many qualitative features of the musculature. The spine was a line of minimum curvature along the back. The high-lysine pigs had higher height-to-width ratios and flatter backs than the low-lysine pigs. The dissected total muscle mass had a –0·66 correlation with the flatness-of-back shape parameter, and a 0·64 correlation with weight.
Keywords: imagery, models, pigs, shape.
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