Visualization Of Wheat Growth Before Overwintering

Virtual plant, which is one of emerging fields synthesizing computer graphics, mathematics, agronomy, ecology, botany and so on, plays an important role in studying of digital agriculture. Virtual wheat is one branch of virtual plant, and fast rendering of wheat growth from CG (Computer Graphics) point of view and botanically faithful description of wheat morphogenetic and eco-physiological structure are challenging problems. Many studies have been made on wheat mechanistic models but only a few studies have been reported on incorporating the growth mechanistic model and visualization model. Even though a mechanistic-based model has been constructed, it's a real problem rendering a 3D wheat growing process from CG which emphasizes on real-time performance and reality. When rendering the wheat laminae or its changing effects of texture, shadow and lights, it's CPU and GPU time-consuming without considering CG optimizing strategy. Meanwhile, simulation of wheat growth without considering its physical functioning and environment is also useless. Thus, a new method taking into account both the growth mechanistic features and visualization model of wheat was put forward, and especially the problem of real-time rendering of wheat growth was studied.The main contributions in this dissertation are the followings:1. An experiment was organized with winter wheat focusing on characterizing development and organ extension before overwintering. From measuring data and former relative models, ecophysiological-based models of a particular wheat were constructed by using the thermal time (oC.d) as independent variable.2. A new image-based 3D reconstruction method, which concentrated on laminae edges, growing curves and the phenomena of laminae twisting and wrapping effect, was put forward. This method was implemented by employing contour tracking method to extract wheat laminae edge data and mapping the 2D edge data to 3D space according to a wheat curve function. Furthermore, an unrestricted laminae model and a restricted laminae twisting and wrapping models were constructed based on the method. The results shown that this new method was convenient for keeping the natural shape of laminae and worked well on simulating twisting and wrapping effect of wheat laminae.3. A new method based on tree structure for accessing and storing geometrical organs of wheat was put forward. By employing Child-Siblings structure, it's convenient for displaying and controlling hierarchy between stems and tillers, and worked better than L-system in this respect.4. A real-time texture-mixing method restricted by growth-period was put forward for describing color-changing phenomena of laminae surface efficiently. The...