Improvements on Multiway ICP Registration for Reconstructing Individual
Plants from 3D Field Scans
Abstract
We present several methods for improving plant reconstruction from
multiple 3D observations. Producing 3D data useful for plant phenotyping
requires proximal sensing (e.g. line scanner, depth camera) at multiple
incident angles (φ) and often with multiple passes. These resulting
individual point clouds must then be assembled into a single point cloud
for analysis. Our interest in improving the registration of individual
plants is focused specifically on observations made within field
settings which present additional challenges over laboratory 3D scans,
where background, overlap and light conditions can be controlled. To
develop these methods, we use several season’s worth of data from the
University of Arizona’s Field Scanalyzer located in Maricopa, Arizona.
Our approach prioritizes: (1) plant completeness, (2) noise reduction,
(3) temporal similarity and (4) computational efficiency. The first
priority is accomplished simply by prioritizing individual point clouds
that contain the majority of the individual plant. 3D field scanning can
result in component point clouds that are from near-identical φ and
cover the same portions of the individual plant. This results in both
additional noise and uncertainties due to small georeferencing errors
and plant movement between scans. Thus, we remove the data that is
furthest in time with non-unique φ in order to achieve priorities 2 and
3. Our method results in small scene reconstruction which has low memory
and computational demands. In order to improve registration further, we
investigate iterative closest point (ICP) registration fitting using
weights defined by crop height distributions and semantic segmentation
point labeling.