Real-Time Rendering Of Dynamic Terrain By Wavelet Transform

Dynamic terrain multi-resolution modeling is one of kernel technologies in modeling under virtual environments, reflects the interaction between entities and the terrain , and faces a wide range of applications in such domains as military simulation, urban planning, etc. Two problems lie in real-time rendering of dynamic terrain: one is compressing terrain data, constructing multi-resolution models; the other is sustaining the multi-precision expanding of the data of deformed region, real-time rendering of the deformed region. Aim at this two problems, this dissertation was based on the analysis and researchment of terrain rendering technologies in existence and wavelet multiresolutional analysis. Taking the characteristics of dynamic terrain application into account, this paper carried out analysis and researchment centering on the multi-resolution denotation, reduction and frame-to-frame consistency and so on:1. According to the characteristic of the 3D terrain elevation data, choosing B-spline wavelet and Mallat arithmetic to dispose terrain elevation data. This method can overcome many problems, such as the hugeness of terrain data, the tardiness of the reducing velocity, bringing biggish error of the signal characteristic between original signal and after transformation and so on.2. View-dependently, distinctive multiresolution were applied to different terrain blocks in perspective. According to the view distance, this paper proposes a rule of wavelet reconstuct continuously of threshold thinning in same resolution. Terrain meshes with various details were dynamically reconstructed in a continuous way. Along with the change of view-point, smooth shift between multiresolutional terrains was realized. Additionally, we have a comparition and analysis for the constructed multiresolution models.3. According to local characteristices represented by constructing terrain models with wavelet and dynamic terrain have changes, Put forward inserting rules and active cell set methods to extend sampling precision of the deformed region. At the same time, the crack and frame-to-frame consistency problems were solved according to the special methods of constructing multiresolution models with wavelet transform.Finally, this method was verified through some experiments, comparing with the former methods for number of triangulations which was needed to come into being LOD and frames per second of terrain rendering. The result indicated that this method can achieve the representation effect of dynamic terrain continuous multiresolution betterly, and satisfy the request of real-time rendering.