Abstract :
[en] Multimodal images fusion has the potential to enrich the information gathered by multisensor
plant phenotyping platforms. Fusion of images from multiple sources is, however, hampered
by the technical lock of image registration. The aim of this paper is to provide a solution to the
registration and fusion of multimodal wheat images in field conditions and at close range. Eight registration
methods were tested on nadir wheat images acquired by a pair of red, green and blue (RGB)
cameras, a thermal camera and a multispectral camera array. The most accurate method, relying on
a local transformation, aligned the images with an average error of 2 mm but was not reliable for
thermal images. More generally, the suggested registration method and the preprocesses necessary
before fusion (plant mask erosion, pixel intensity averaging) would depend on the application. As a
consequence, the main output of this study was to identify four registration-fusion strategies: (i) the
REAL-TIME strategy solely based on the cameras’ positions, (ii) the FAST strategy suitable for all
types of images tested, (iii) and (iv) the ACCURATE and HIGHLY ACCURATE strategies handling
local distortion but unable to deal with images of very different natures. These suggestions are,
however, limited to the methods compared in this study. Further research should investigate how
recent cutting-edge registration methods would perform on the specific case of wheat canopy.
Name of the research project :
Natural Resources and Environment Research Direction of the Public Service of Wallonia (Belgium): project D31-1385 PHENWHEAT
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