Figure 3

Example of a complete canopy surface reconstruction. Illustration of a complete leaf surface modeling process using the example of a young sugar beet population: The modeling starts with the computation of calibrated stereo images taken with an ordinary stereo setup (top left). These images are used in depth estimation (disparity map - top middle) as well as in leaf segmentation (top right). Jet coloration in the disparity map encodes the distance from the camera with blue values being the farthest. The slight off-nadir position of the stereo rig is reflected in the smooth transition of ground values. The enlarged detail displays the image after post-processing, i.e. filtering of the background, occlusions and outliers. Identification of leaf-specific pixels is illustrated in the segmentation image (top right - color-indexed leaves). Results are used for leaf-specific surface modeling (bottom - in this example surfaces have been reconstructed with curvature flow smoothing). After correcting the off-nadir position all surfaces yield the complete 3-d canopy surface reconstruction.