Component-Based Visualization Technology Of Wheat Growth

Virtual crop is to simulate crop morphological architecture and growth processes in3D space visually on computer, at the levels of organ, individual and population which are taken as the objective of this study. Visual crop is development of crop growth simulation system, and has wide application prospects in agronomic reseach, teaching and crop management. The primary objectives of this study were to adopt the multidisciplinary theories and technologies from crop science, computer graphics and virtual reality, develop the key techniques for wheat morphological models, realistic rendering,3D reconstruction and real-time rendering of wheat population based on the existing morphological models, and then establish wheat growth visualization components and system based on Microsoft.Net platform. The results would lay a technical foundation for plant type design and production management and regulation.Based on observation and analysis on morphological structure of wheat organs and individual,architectural parameter-based geometrical models for wheat leaf and spike were developed by using3D geometric modeling technology. The NURBS surface was used to simulate leaf geometrical deformation, and wheat spike geometrical model was developed by assembling single organs:the ear axis proglottids were simulated by slant cylinder; triangular faces were used to simulate the awn and outer bran based on their curves; the anther was simulated with NURBS surface; and the spike shape was controlled by using a hierarchical model. According to the topological structure, the organ submodels were organized together to rebuild the whole3D geometrical model of wheat spike. Based on the wheat topological structure, a geometrical model of wheat individual aboveground organs and root coupled was developed by integrating the existing research results of our laboratory. Finally, the geometrical models of wheat organs and individual were developed based on organ morphological characteristic parameters and individual topological structure which were output of wheat morphological model.Based on the geometrical models of wheat organs and individual, realistic rendering technologies such as color rendering, texture mapping, lighting and shadow rendering were proposed. Realistic organs and individual were realized on computer based on OpenGL graphic library. Color rendering combined with color submodel of wheat morphological model can accurately reflect the color dynamic change process during whole wheat growth period. Integrated factors of variety, weather, water, nitrogen and other environments, organ texture mapping databse was constructed, and expression of organ surface details were achieved. The sunlight simulation at different times of a day was achieved based on the lighting model in OpenGL. The shadow rendering of wheat organs and individual were realized simply and efficiently by using planar shadow algorithm. Experimental results showed that the proposesed realistic rendering algorithms are efficient and easy to implement, the wheat organs and individual showed high realistic.A method integrated multi-technology for real-time rendering of wheat population growth was proposed. Firstly, on the basis of wheat population morphogenesis, the differences among the single plants were analyzed. The sample number was determined and encapsulated for tree-structured display lists. Then, wheat individual model with different levels of details were constructed according to the method of constructing organ geometrical models; based on the viewpoint, visual angle and sight line to guide the frustum culling, space division and level of details selection. Finally, real-time rendering of wheat population was realized based on the visualization of individual plant growth. The experiment results showed that the method for visualizing wheat population could correctly describe the characteristic architecture of wheat population.Finally, driven by weather, soil, variety and management databases and integrating wheat morphological model and visualization model, the compnents of wheat organs, individual and pupulation and visualization system were established by using component-based programming technology. The system was programmed with Microsoft.Net platform and OpenGL graphics library. The implemented system could be used for predicting wheat growth processes and visualizing morphological architecture of wheat under various growing environments and management strategies. The system for visualization of wheat3D morphology at organ, individual and population levels would be useful for improving the level of digital and visual crop growth system and further developing virtual farming technology.