Improving the automatic measurement of plant root growth

The measurement of plant root growth is important in gauging the effect of experimental changes (nutrients, illumination, orientation, etc) made to plants. The most commonly used software is a combination of the common optical flow measurement method of Horn and Shunk with a ruggedized backward forward block matching method. The best results for this method show a low reliability for the optic flow measurement (less than 5%) and mostly rely on the ruggedized backwards forwards block matching. The current paper demonstrates that by correct tuning of the aperture a scale space based optical flow measurement can produce a higher reliability than the former tensor method. In addition, when the output of the scale space optical flow measurements are used to constrain the search space of the block matching method a still higher reliability is achievable. Systematic errors introduced by the forward backward matching with a non-optimally constrained search space are also eliminated.