Abstract
Physiological dynamics at plant level are essential but also challenging
for precision agriculture applications linked to plant phenotyping. In
this study, we explore not only the spatial dynamics of corn in field
conditions but also their temporal analysis via skeleton reconstruction
of individual plants as a shape descriptor. For this purpose, an
optimized approach for high-throughput was developed by point cloud data
derived from UAS imagery. The curve-skeleton extraction is calculated
based on a constrained Laplacian smoothing algorithm. The experimental
setup was performed at the Indiana Corn and Soybean Innovation Center at
the Agronomy Center for Research and Education (ACRE) in West Lafayette,
Indiana, USA. On July 27th and August 3rd of 2021, two flights were
performed over a trial with more than 200 maize plants using a custom
designed UAS platform with a Sony Alpha ILCE-7R photogrammetric sensor.
RGB images were processed by a standard photogrammetric pipeline by
Structure from Motion (SfM) to get a scaled 3D point cloud of the
individual corn. Filtering techniques and labeling algorithms were
joined together to reconstruct a robust and accurate skeleton of
individual maize. Therefore, significant traits such as number, length,
growth angle and elongation rate of leaves and stem can be easily
extracted. Height variations computed from the skeleton at the two dates
show a coefficient of correlation with on-field measurements better than
92%. Our experimental outcomes demonstrate the UAS-data’s ability to
provide practical information to efficiently select phenotypes in plant
breeding programs.