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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
1

Simulation of realistic leaf behavior and interaction with external forces for virtual reality landscapes

Wong, Jason January 2009 (has links)
[Truncated abstract] Currently, one of the active areas of research in computer graphics is related to creating realistic images and animations that mimic the world we see around us. There has been significant work in modeling and simulating natural phenomena such as fire, clouds, water, and vegetation. Some of these works are employed in the entertainment industry, especially as special effects in cinematic films. Of particular interest is the area of vegetation, given the possible structural complexity and variation in different types of plants. This provides a challenge to develop methods and techniques that effectively and realistically model the movement and behavior of plants. In response to this challenge, there has been significant work in the area of modeling plant structure, as well as modeling of the dynamics and wind interaction of tree branches. However, there is a distinct lack of approaches involved with modeling the dynamics and behavior of individual leaves. Most of the previous approaches focus on the modeling of the branches of a tree, and rarely consider the movement of the leaves in detail. This makes it particularly hard to model the interactions of plants with relatively large leaves, where the dynamics of the leaves are important. In other words, there is no method that could effectively simulate the lower canopy of a forest or jungle, where there are many ferns, saplings, and other broad-leafed plants. Therefore, I present in this thesis a leaf animation system that is designed specifically for simulating and animating plants with relatively large leaves with realistic dynamics in real-time. .... These interactions illustrate the flexibility and robustness of the leaf movement model. In particular, I present a novel approach in modeling volumetric wind through the wind cube that approximates wind behavior such as obstruction by leaves, and constructive and destructive interference. This unique approach is based on modeling wind as a spatial collection of wind vectors and the interaction of the vectors is governed by the rules of each cube-shaped cell of the wind cube. In the end, this wind cube allows for convincing behavior of wind and the subsequent interaction with the leaves of a plant. The leaf animation system is also suitable for simulating a number of plants in a landscape. This is possible through another novel method of reducing the rendering time to allow for more plants to be simulated. This method involves using an animated texture in place of plants that are far from the camera, when the difference visually is not blatantly noticeable. This is a form of the commonly used levels of detail to reduce the complexity of the landscape, but my method is novel in that it has not been implemented in a way where the texture itself is animated in place of the plant. I investigate the strengths and limitations of this approach in reducing rendering time for a landscape of plants. Thus, the leaf animation system is suitable for realistic and interactive virtual reality environments. These virtual environments feature heavily in current video games that involve realistic and believable worlds. In addition to the film and video game industry, these virtual environments are also integral in the application of virtual reality as psychological therapies.

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