Research On Real-time Rendering Technology For Complex Forest Scene

Modeling and visualization of forest landscape dominated three-dimensionalscene is a hot issue in forestry science research field, which provides a new techniquesfor forest informatization，and plays an important role for promoting the developmentof digital forestry. However, the popularization application of the visualization offorest landscape has been trapped in the real-time rendering technology. Becauseforest itself is a complex system, in which plant species are numerous and different inshape and form. The forest scene is rich in content, including sky, land, water andthose landscapes fixed on the land. Thus, the real-time rendering of such complexforest scene is also a challenging subject.In this paper, the forest trees, berbs, water and common environment factors areresearch object, and the study on object modeling and scene real-time rendering iscarried out. The scene takes real-time as premise and realistic is also considered at thesame time. The main work and achievements are given as follows:(1) Tree morphology structure modeling. Based on Tree architecture, theparameterized tree modeling method is presented according to treemorphology structure characteristic. Parameterized generalized cylinder is used toexpress stem, branch and organ, such as leaf, flower; fruit is expressed by billboard ororgan model. To meet complex forest scene real-time rendering, the tree LODsimplifying method is presented according to branch affiliation.(2) Large-scale trees accelerative rendering. To deal with the problem ofrendering the forest scene, which contains numerous trees, complex models, severalaccelerative rendering strategies are presented in this thesis, such as view-dependentLOD technology to reduce the total triangular surface, template instancing technologyto decrease memory usage, uniform render state managements to slow down theusage of texture change.(3) Understory herbs real-time rendering. Herb unit is built by billboard andhardware instancing technology is used for rendering massive herbs. Animation ofherbs in wind is simulated based on GPU-Accelerated technology.(4) Realistic water rendering. As a major component of the forest scene, watercan increase the scene reality largely. In this paper, perlin noise, vertex displacement and GPU-Accelerated technology are used for the water grid building, water wave andoptical Simulation.(5) Common environment factors simulation. Rain，snow and fog are commonenvironment factors, which can give variety to the forest scene and increase the scenereality largely. In this paper，the rain and snow is simulated by particle system andcolor fusion method for fog.(6) Implementation on forest visualization prototype system. Designing&realizing the forest visualization prototype system, and carrying out forestenvironment simulation application. Consequently, the validity and applicability ofproposed a variety of techniques were proved by those simulation results.