Tang Liyu

Geometrical shapes and swaying movements of realistic tree: design and implementation

Trees and plants are important elements of outdoor scenes, therefore, it makes demands of research involved in computer graphics on methods to realize the natural-looking trees and plants in various environmental condition, such as windy or stormy weather, to contribute more facticity to the virtual reality. The paper starts from introducing the general background. Then, an approach adopting a series of statistical curves as inputted parameters of tree morphogenesis and motion depiction, which represent ramification modes, phyllotaxes or motion profiles of leaves and stems. Finally, some experimental models in virtual scene were showed. We focus on the faithful morphogenesis of tree, swaying motion in wind and the appropriate rendering speed. Aside, all the inputted statistical curves can be modified interactively to integrate the research work of botanists and other experts, which vary with species and districts. Within this methodology, various plant models can be created easily and rapidly without any botanic background, and faithful motion of tree in wind can be simulated easily with proper engineering accuracy and effective computation.Trees and plants are important elements of outdoor scenes, therefore, it makes demands of research involved in computer graphics on methods to realize the natural-looking trees and plants in various environmental condition, such as windy or stormy weather, to contribute more facticity to the virtual reality. The paper starts from introducing the general background. Then, an approach adopting a series of statistical curves as inputted parameters of tree morphogenesis and motion depiction, which represent ramification modes, phyllotaxes or motion profiles of leaves and stems. Finally, some experimental models in virtual scene were showed. We focus on the faithful morphogenesis of tree, swaying motion in wind and the appropriate rendering speed. Aside, all the inputted statistical curves can be modified interactively to integrate the research work of botanists and other experts, which vary with species and districts. Within this methodology, various plant models can be created easily and rapidly without any botanic background, and faithful motion of tree in wind can be simulated easily with proper engineering accuracy and effective computation.

Interactive Physical Based Animation of Tree Swaying in Wind

Lots of researches have been done on computer animation of tree swaying in wind. Some of them employed artificial simplification methods which could not achieve faithful swaying motion, others adopted complicated physical principles which would involve vast computation and fail to get an appropriate rendering speed. This paper presents a series of convenient interactive physical based methods for animation of trees swaying in wind. We focus on both the faithful swaying motion and the appropriate rendering speed. Therefore, a lot of statistical curves, representing wind profile loaded in tree or stem displacement profile and so on, are introduced for swaying motion calculation. All those curves can be modified interactively to get best match with the researches of botanists and other experts. These methods can be adjusted quickly and conveniently to simulate the animation of faithful tree swaying in wind with proper engineering accuracy and effective computation.

Terrain rendering technology based on vertex texture

According to the Vertex Texture Fetch technology in Shader Model 3.0, we designed a terrain rendering algorithm based on vertex texture. The algorithm storages the data of terrain as vertex texture, and get elevation value through the vertex shaders. During rendering phase a group of nested grids are built centeredly around current viewpoint. Elevation values are sampled from the vertex texture according to two-dimensional coordinates of the grids. Then the whole data are sent to GPU for rendering. The algorithm can reduce the CPU load and make full use of the powerful float computing and programmability feature.