小麦地上部器官几何造型与可视化研究

Geometry Modeling and Visualization of Above-ground Organs of Wheat

为了精确重构小麦三维空间形态,增强几何模型与品种特性及作物模型间的衔接,通过对小麦植株拓扑结构和形态结构的观测分析,对叶片、穗、茎秆等地上部器官几何造型算法进行了研究。结果表明,小麦叶脉曲线可用比叶重、叶倾角和叶长3个参数确定,进一步与叶形和叶片边缘几何造型模型整合,能够对小麦叶片生长、卷曲以及扭曲等进行精确描述。在麦穗几何造型中,使用偏圆柱体重构穗轴节片,以二次曲面代表颖片、稃片,可以实现麦穗的参数化建模。通过定量化小麦植株拓扑结构和器官的形态特征参数,采用结构化建模途径,在VC++6.0集成开发环境和OpenGL图形平台上驱动器官几何模型,可以快速精确重构出不同生育时期的小麦三维形态,并实现可视化显示,重构出的小麦植株具有较强的真实感。因此,基于形态特征参数的小麦地上部器官几何造型算法能够较好地实现器官及植株的精确重构,且易于交互、可控性强。

In order to reconstruct the 3-dimentional structure of wheat plant precisely, to enhance the connections between geometry models and variety traits or crop models, the study on the algorithm for parameter based geometry modeling of above-ground organs was made by the way of observation and analysis of topological and morphological structure of wheat plant. The result showed that the leaf curve model based on the equation of slanting parabolic motion was controlled by specific leaf weight, leaf angle and leaf length. These parameters have definite agronomic meanings and could be easily integrated with variety traits and crop models, and easy to collect. Combined with leaf shape and leaf edge parameters, it is possible to describe the curvature and twist of leaf blade precisely. Rhaehis and rachilla were constructed by connected proglottids which represented by slant cylinders; glume and palea were reassembled by quadratic surface. Rhachis, rachilla, glume and palea were used to build the entire spike model. Finally, via the functions, such as rotation and translation provided by OpenGL, the leaf model, spike model and stem model were reconstructed respectively, and then, according to topological structure and quantified morphological structure parameters, these organ models were precisely organized together to rebuild the whole 3-dimentional wheat plants in different growing stages. The geometry model visualization was realized in use of Microsoft Visual C＋＋ 6.0 integrate develop environment and OpenGL platform, and the reconstructed wheat plant in computer is authentic. The result demonstrated that the algorithm proposed in this article is useful in the precise reconstruction of 3-dimentional wheat plant, and the morphological parameter based geometry models shows high controllability and are easy to interact with users.