Sub-shape Theory And The Skeleton Model In The Soil And Root Visualization Applications

The combination of computer graphics technology and agricultural knowledge has stimulated the researches of plants and their interactions with vegetal environment have to the digital and visual phase. It is possible to analyze, research and design modal structure, vegetal environment, growth process with three-dimensional and visual mode on computer. Basing on the fact that soil is the most fundamental survival environment for plant and root system is the interactional ligament for plant and soil, it is very important to carry out visual study on soil and root system. It not only can impulse and facilitate the research of digital plants effectively, but also has the affirmative function for applications and extension in related computer technology domain.In this paper, the edaphic holes structure, three-dimensional visual technique of soil and three-dimensional visual interactive modeling of corn root system were studied using computer graphics knowledge and techniques. Results are listed as follows:Firstly, the three-dimensional visual structure of edaphic holes is modeled by using Koch curve. The traditional Koch curve was extended from two dimensional to three dimensional spaces based on generalized energy minimum theory. The relationship between soil holes aperture and depth was established and special distribution of each holes channels was determined. The soil hole was rendered with layer by layer paintingtechnique. This model was validated through "virtual soil"experimentation finally. The result demonstrated that soil holes rebuilt in computer could well represent structural character of given soil holes with realistic effects.Secondly, soil structure and granule visual modeling is achieved with particle system. Soil particle system modeling framework was built and nine basic soil particles were defined. In this framework, afterinitiating the state of the particle system, soil particle system'smovement variety was analysed and determined. The visual soil was gained via particle movement. This model was validated by computing holes density of three different soils. The result and trend of soil movement corresponded well with reality.Thirdly, method for enhancing real time performance of particle system was analyzed. The speed of simulation is increased to some extent.Fourthly, the visual walkthrough of inner structure in virtual soil is implemented by using viewpoint controlling technique and octree collision detection method.In the end, three-dimensional interactive design for corn root system is implemented. Corn root system topology structure was determined with interactive sketch model and density function was designed to ascertain quantity and distribution of its ramus. The similar parts were derived from template and the first-degree side root and fibril were generated with parametric random L-System. The whole corn root system was integrated finally.