NON-DESTRUCTIVE GROWTH MEASUREMENT OF SELECTED VEGETABLE SEEDLINGS USING ORTHOGONAL IMAGES

Abstract

A non-destructive measurement method of plant features using image processing technique provides a means toanalyze the continuous growth process of a plant. In a previous study, we developed a non-destructive measurement methodby using elliptical Hough transform to search for seedling leaves from a top-view image. To improve the accuracy of the leafnumber estimation and leaf area measurement, this study further incorporates two side-view images with a top-view imageto extract and reconstruct the three-dimensional structure of selected vegetable seedlings, and thus to measure the featuresrelated to plant growth. By registering correspondences between the three orthogonal images, the position, orientation, anddimensions of leaves in a seedling can be more exactly derived than from a single top-view image alone. The leaf skeletonstraced in the side-view images can be used to correct the projected leaf area in the top-view image for better estimation ofleaf area. Experiments were performed to test the performance of the measurement system by comparing the non-destructivelyestimated leaf area and the actual leaf area of selected vegetable seedlings. The average relative errors of total leaf estimationfor cabbage and broccoli seedlings were 14.5% and 13.1%, respectively, using a single top-view image. By incorporatingorthogonal images, the relative errors were significantly reduced to 1.6% and 4.9%, respectively. Using this non-destructivemeasurement system, the continuous growth of vegetable seedlings can be effectively measured.