Computer Simulation Of Typical Fruit Diseases

Fruit disease is a common phenomenon during the growth of fruit, which seriously affects the production and value of fruits. Using computer simulation method, the above process can be modeled and reproduced quantitatively, which can replace the time-consuming, laborious and expensive fruit disease experiments. In addition, visualization of the changes in the three-dimensional fruit can increase the realism of the model, with wide applications in film and television making, computer games, etc. Although the simulation of many kinds of natural phenomena has been studied in the field of computer simulation and graphics, the reproduction of natural decay processes has not received much attention. Visual simulation methods not only focus on the changes of the external surface of fruits, but also account for the biological principles of fruit deterioration, making the simulation more accurate. Our research mainly focuses on visualization of fungal diseases and physiological diseases. Fruit ring rot is the representative of fungal diseases, and sunscald is the representative of physiological diseases. We mainly study the disease process simulation method, and design the method combining the macroscopic and microscopic simulation method based on physiological characteristics.This thesis proposes a new method to simulate ring rot which is the representative of fungal disease. The most obvious external symptoms of ring rot are the typical shades of white on the fruit surface. By simulating the propagation and growth of bacteria microcosmically, we obtain the colony morphology which is the final appearance of fruit symptom. In order to simulate the process of fruit ring rot, an improved reaction diffusion model was adopted to model the colony formation. This model can simulate the growth and movement of fruit ring rot accurately. The initial nutrient parameters can be friendly designed according to ring rot characteristics. The software of Maya is used for fruit modeling and disease area rendering.Besides, this thesis proposes a computer simulation method for sunscald which is the representative of physiological disease. We mainly focus the morphology change of fruit appearance affected by sunseald disease under the condition of water loss. An improved mass spring model is proposed, by combining cell turgor pressure with mass spring. We adopt this physical deformation model for dynamic simulation of fruit sunscald disease. We use the software of Maya to get the geometric model of fruit first. Then, we get the physical model based on our improved model, using the spherical cell mechanics model filling with liquid. Next, we generate the local grid of pathological area. According to water metabolism equation, we calculate cell turgor pressure variation due to water loss. We thereby get displacement changing of every mass particle in our simulation system. Finally, using Maya to render the deform model to get the simulation result.