CAJ | 학술논문

针对人为操作 L 系统进行植物形态建模时存在盲目性和低效性的问题,该文提出一种智能化的植物形态可视化建模方法.该方法利用基因表达式编程思想自动获取 L 系统产生式规则,进而模拟出特定的植物形态结构.在分析现有工作的基础上,提出限制性的初始种群设计策略和种群个体选择策略,以缩小算法的搜索范围;提出一种综合外围轮廓比较和 Hausdorff 距离计算的个体适应度评价函数,以自动筛选出每一代中的优良个体.该方法使用 OpenGL 在 NVIDIA GeForce3图形硬件上实现.试验结果表明,该方法不仅能逼真地模拟指定植物的三维形态,还可以仿真出形态各异的植物图形.该方法可为虚拟植物建模提供参考.
침대인위조작 L 계통진행식물형태건모시존재맹목성화저효성적문제,해문제출일충지능화적식물형태가시화건모방법.해방법이용기인표체식편정사상자동획취 L 계통산생식규칙,진이모의출특정적식물형태결구.재분석현유공작적기출상,제출한제성적초시충군설계책략화충군개체선택책략,이축소산법적수색범위;제출일충종합외위륜곽비교화 Hausdorff 거리계산적개체괄응도평개함수,이자동사선출매일대중적우량개체.해방법사용 OpenGL 재 NVIDIA GeForce3도형경건상실현.시험결과표명,해방법불부능핍진지모의지정식물적삼유형태,환가이방진출형태각이적식물도형.해방법가위허의식물건모제공삼고.
The plant simulation based on computer modeling and visualization has become an important topic in the scientific researches, such as the researches of computer graphics, agroforestry, and ecology. Due to the complexities of plant structure, especially in the modeling of large-scale scenes of natural environments, how to quickly and efficiently establish models of the scenes using computers has been a research focus in the area of plant modeling. It is a key step to select appropriate morphogenetic model to simulate morphology and architecture in plant modeling. However, it is needed to artificially extract the parameters of the model based on the priori knowledge of the plants in order to simulate the realistic plant morphology as required, no matter what kind of morphogenetic model is chosen. Larger number of parameters for the rules will be needed in the modeling of large-scale scenes. Extraction of the parameters for the rules based on the artificial method is time-consuming and laborious. Thus it is particularly important to develop a method for efficiently extracting the rule parameters in simulating different types of plants. In this study, an intelligent method for simulating and visualizing plant shape was proposed, aiming at solving the problems caused by blindness and low efficiency when only using L-systems to simulate plant shapes by manual way. The production rules and the initial axioms of the model with L-systems were obtained by this method. Then the spatial structure of specific plants based on the concepts of gene expression programming was simulated. We proposed a restrictive strategy to design the initial population with the control of the branch number and the morphology of individuals, which can be used to guide the evolution of simulated plants towards the target shape and reduce the searching scope with the algorithm. The method was developed based on the analysis of previous studies, the most of which were using traditional genetic algorithms to generate the initial population in a completely random way. Besides, we proposed a selecting strategy to automatically select the optimal individuals in each generation, and thus preserve better traits of the population, which can further improve the efficiency of the algorithm. Using the genetic manipulations to simulate the evolution processes, i.e. one point crossover, two point crossover, gene recombination, transposition, and mutation, the population with morphological diversity can be generated. We also proposed an individual fitness evaluation function which is integrated algorithm of plant outline comparison with Hausdorff distance calculation method. Combined the fitness evaluation function with the proposed evolutional algorithm, the optimal individuals in each generation can be selected, so that the evolution speed can be increased greatly. The method proposed in this study has been implemented with the graphics hardware, NVIDIA GeForce3, using OpenGL functions. The simulation results indicate that the proposed methods can not only simulate the special plant morphology, but also the normal plant morphology with various types. The method will promote the development of plant simulation models and also provide a reference in the exploring of new methods for virtual plant modeling.