Plant growth measurement techniques using near-infrared imagery

We examine the usefulness of various imaging techniques, including optical How, for measuring plant growth for corn seedlings and caster oil bean leaves. A near-infrared camera, which allows one to measure optical flow in the light and in the dark, is used. For corn seedlings we have already used optical flow to obtain 3D image velocity as a measure of growth performance. We propose two new growth metrics for measuring growth, one based on elongation of the stem/leaf and the other based on the area change of the stem/leaf. These metrics are examined by measuring the corn seedling growth under various combinations of root temperatures (warm or cold) and under various lighting conditions (light to dark). For caster oil bean leaves we use Horn and Schunck's optical flow algorithm to compute the globally consistent flow field for a moving, growing leaf. We use first order divergence of the flow to hypothesize where growth might be taking place.