改进区域增长算法的植株多视图几何重建

Multi-View Geometric Reconstruction of Plant Based on Improved Region-Growing Algorithm

【目的】通过研究3种不同复杂程度植株冠层的三维重建,为更加精准获取植株冠层表型参数提供新方法。【方法】本文首先用单反相机获取3种不同复杂程度植株冠层图片序列,通过三维重建得到各植株稠密点云;随后还原植株点云原始尺度,过滤稠密点云中的噪声,再使用改进区域增长算法分割植株点云冠层;之后借助激光扫描仪,利用手动测量和激光扫描方法分别从二维和三维两个方面对多视图几何重建的叶片进行精度评价,二维精度评价为叶片长宽的实际测量值分别与激光扫描仪获取的叶片的长宽值和多视图几何重建叶片的长宽值进行统计分析,三维精度评价使用传统的网格对比方法豪斯多夫距离与更加精准的工业级网格3D精度对比检测软件Geomagic Qualify。【结果】多视图几何重建的植株叶片表型信息与手动测量值间的判定系数(R2)均高于0.96,激光扫描方法获取的植株叶片表型信息与手动测量值间的判定系数(R2)均高0.99;多视图几何重建的叶片与激光扫描得到的叶片在0-±1mm偏差范围内的比例大部分达到97%以上;以激光扫描的叶片网格为参考,多视图几何重建的叶片网格的豪斯多夫距离90%以上分布在0-2 mm。本研究的多视图几何重建方法与改进区域增长算法相结合能对不同复杂程度的植株取得比较理想的重建结果。【结论】本文提出的多视图几何方法与改进区域增长算法相结合的重建方法可以弥补区域增长算法的不足,对表面不平滑的植株冠层具有更好的分割效果,适合不同复杂程度植株三维重建,为育种研究获取植株表型提供一定的参考。

【Objective】 Three-dimensional reconstruction of three kinds of plants canopy with different levels of complexity was studied to provide a new method for more accurate acquisition of plants canopy phenotypic characteristics.【Method】 In this paper, a sequence of pictures of three kinds of plant canopy with different levels of complexity were gotten by using a SLR camera,and dense point clouds of plants were gotten by using three-dimensional reconstruction method. Then, the original scale of dense point clouds of plants was restored, and noisy point of dense point clouds and segmenting plants canopy were filtered by using improved region-growing algorithm with the help of laser scanner, then the accuracy of leaves reconstructed from multi-view geometry method was evaluated from two-dimensional and three-dimensional aspects by manual measurement and laser scanning.Two-dimensional accuracy evaluation was carried out by statistical analysis of actual measured values of leaves length and width and comparing with leaves length and width reconstructed by multi-view geometry method and leaves length and width obtained by laser scanner, respectively. Three-dimensional accuracy was evaluated by using the traditional mesh comparison method Hausdorff distance and Geomagic Qualify software, which was a better accurate 3 D accuracy comparison software in industrial meshes comparing.【Result】 The results showed that the judgment coefficients(R2) between the phenotypic information of plants leaves and manual measurements were higher than 0.96. The judgment coefficients(R2) between the phenotypic information of plant leaves obtained by laser scanning and manual measurements were higher than 0.99. The proportion of leaves obtained by multi-view geometric reconstruction and laser scanning was more than 97% in the deviation range of 0-±1 mm. Taking the leaves mesh scanned by laser as a reference, more than 90% of the Hausdorff distance of the leaves mesh reconstructed by multi-view geometry was between 0-2 mm. It was proved that the combination of the multi-view geometric reconstruction method with the improved region-growing algorithm could achieve ideal reconstruction results for plants with different complexity.【Conclusion】The reconstruction method combining multi-view geometry method with the improved region-growing algorithm proposed in this paper could make up for the shortcomings of region-growing algorithm. It had better segmentation effect on the surface of uneven plants canopy, and was suitable for three-dimensional reconstruction of plants with different complexity. It could provide some reference for breeding research to obtain plant phenotypes.