3-d field phenotyping of crops using laser scanning and photogrammetric approaches

Several approaches are currently established in the German Plant Phenotyping Network (DPPN) to measure shoot properties of barley, sugar beet and rapeseed plants in the field under natural conditions. The portfolio of methods aims at covering plant geometries and developmental stages characterized by different architectures (branching, leaf orientation, level of occlusions). Imaging methods will be integrated into three field platforms: a cherrypicker (FieldLift), an in/outdoor XYZ-positioning system (miniplot-facility at Campus Klein-Altendorf), and an automated vehicle with XZ-positioning system (FieldCop). Platforms are featured by different payloads, measurement heights, flexibility in the field and sensor movement capabilities and are primarily designed for a nadir positioning of the sensor above the canopy. The portfolio of field methods has been set up to cover various measurement areas and includes a high-precision methods (light sectioning with a depth resolution < 0.2 mm), mid-scale methods (RGB-cameras) and large-scale methods (3-d laser scanner up to a range of 130 m). There is a variety of shoot traits, which can be estimated from the resulting 3-d point clouds and surface reconstructions. Traits of interest are plant height, leaf area, leaf angles, leaf surface properties and the respective distribution of these parameters across the field. So far, photogrammetric approaches have been used to analyze the leaf angle distribution of sugar beet plants in the stand. For this purpose an image processing pipeline has been implemented to calculate the leaf angle distribution from segmented leaves and the resulting leaf-specific 3-d point clouds