Abstract
For field workers around the world, wheat trials are often synonymous
with wheat heads counting: a tedious but important task to measure this
important yield component. Deep Learning has been a promising solution
to automate the acquisition of wheat head density from a high-throughput
phenotyping system, but it has been shown to be sensitive to changing
acquisition conditions, also known as “domain change.” In response, an
international collaboration built the “Global Wheat Head Dataset” in
2020 and 2021, a collection of 6515 images acquired during 47 different
acquisition sessions in 12 countries. In addition to these datasets, two
data competitions were held in 2020 (Kaggle, over 2,200 competitors) and
2021 (AIcrowd, over 400 competitors). The winning solutions are expected
to be usable in plant phenotyping pipelines to robustly assess wheat
spike density. We tested this hypothesis by evaluating the 2021 winning
solution on an independent dataset consisting of images measured both in
the field and in the image by a human, taken with the same acquisition
protocol. We use triple collocation analysis to demonstrate that the
predicted density appears to be more reliable than the human density
measured in the field and in the image. Furthermore, we demonstrate that
Global Wheat Head Dataset can be used to estimate wheat ear density from
a drone.