Abstract:

On the basis of geometric modeling techniques of the virtual plant and virtual organ, a modeling method of virtual fruit was proposed. Its key techniques adopted for fruit simulation are a three-dimensional free-form axis of curve and a figure control curve, both of them using Bezier curves. The fruit model is determined by fruit shape, thus three-dimensional models for different fruits are achieved by different curves with separate parameters. Simultaneously, multiple realistic technologies are imposed on the model to get a more realistic appearance, such as the bump mapping, hidden technology, light treatment, etc. Taken longan as an example to simulate solitary fruit, various growth stages of longan fruit are simulated according to the biological characteristics of longan fruit growth and development. The model, which has clear botany meaningful parameters, is not only easy to understand, convenient for computer implement, but also having better controllability, high accuracy and versatility. It is suitable for geometric modeling of all kinds of fruit, and is of certain significance for virtual fruit modeling and growth simulation research. It has provided an assistant tool for controlling longan fruit growth and managing an invented orchard.

Key words: fruit modeling, ventral axis modeling, Bezier curve, normal mapping, growth and development process, longan

摘要：

通过对虚拟植物植株和器官两级几何建模,提出一种以Bezier曲线为核心、结合三维自由曲线轴和果实外形控制曲线的植物果实建模新技术。根据果实的不同品种,分别确定轴曲线和半径控制曲线,以实现外形各异的果实三维模型。同时,运用消隐处理、光照处理、凹凸纹理映射等多种技术对生成的果实模型进行真实感处理,以提高模型的逼真程度。基于所设计的建模方法,以龙眼果实为例,进行单果建模与仿真,并依据龙眼果实生长发育的生物学特性,结合果园实地考察与观测,对其生长发育过程进行模拟,生成不同生长阶段的虚拟龙眼果实。该果实模型构建方法,模型参数的植物学意义明确、易于理解、便于计算机实现,构建的模型具有可控性好、精确度高、通用性强等优点,适合于多种类果实的几何建模,对于果实三维几何模型的构建和生长过程模拟研究具有一定的借鉴意义,为龙眼果实的生长调控和虚拟果园的经营管理提供一种辅助工具。

关键词: 果实模型;中心轴模型;Bezier曲线;凹凸纹理;生长发育过程;龙眼