3D phenotypic measurement of bitter gourd seedlings based on monocular structured light

Abstract

Accurate 3D morphological characterization is critical for precision breeding. However, traditional phenotypingmethods suffer from inherent limitations such as low efficiency and loss of dimensional information. To overcome theselimitations, this study proposes a robust three-dimensional phenotypic analysis framework based on the monocular FringeProjection Profilometry (FPP) method. This method is specifically optimized for the high-precision measurement of youngplant leaf features. The framework employs a hybrid decoding strategy combining 12-step phase shifting with complementarygray codes to resolve phase ambiguity and reconstruct dense point clouds at sub-millimeter resolution. It addresses theproblems of leaf occlusion and adhesion using the section segmentation method. Based on the Oriented Bounding Box (OBB)method of principal component analysis (PCA) and Delaunay triangulation technology, it achieves precise quantification of keyphenotypic parameters such as leaf length, width, inclination angle, and area. Systematic verification using 72 bitter gourdseedlings as samples indicates that this method has an extremely high consistency with manual measurement results: thedetermination coefficients (R2) for leaf length, leaf width, and leaf inclination angle reach 0.9992, 0.9991, and 0.9933respectively, with corresponding root mean square errors (RMSE) as low as 0.68 mm, 0.54 mm, and 0.92°, and the R2 for leafarea reaches 0.9996. This system achieves the complete process from raw scanning to parameter extraction in a low-cost, non-contact, and semi-automated manner, providing reliable data support for the digital perception and intelligent gradingstandardization of seedling growth dynamics in precision breeding. Keywords: fringe projection, phase unwrapping, 3D reconstruction, leaf phenotyping DOI: 10.25165/j.ijabe.20261904.10643 Citation: Li B, Duan W W, Li Y B, Liu Y D, Chen G, Ouyang S T, et al. 3D phenotypic measurement of bitter gourd seedlings based on monocular structured light. Int J Agric & Biol Eng, 2026; 19(4): 191–202.

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