Study On The Theory And Method Of Road Route Real-time 3D Visualization Design

Route design is a kind of synthetic planning and designing work, which involves in many specialities. Route designer must analyse the natural conditions such as topography, geology, hydrology etc, to design the road location which has to meet the requirements of politics, economy and technology. Because the decision of road location depends on designer' s analysis to the natural conditions, route design has more dependency on the natural environment than many other engineering designs. So, if designer can observe the road virtual 3D environment in real time and be immerged in it to conduct dynamical interaction during the design process, it is no doubt that will be great beneficial to optimize road location and to improve design quality.This thesis studies on the key theories and major technologies involved in the road real-time 3d visualization design, and presents a set of methods in modeling and algorithms. The chief research contents and achievements can be summarized as follows:1) Based on the Delaunay triangulation theory, the synthesis algorithm for integrally constructing 3D terrain model is put forward and realized. This algorithm takes the advantage of the incremental insertion algorithm and the divide-conquer algorithm, and has high efficiency and small space cost. It is proved that the time complexity of the algorithm is 0(AT) in general and O(NlogN) at worst cases. The test shows that the constructing speed reaches 70000 triangles per second on normal PIV computer. Furthermore, the paper presents a line oriented locating algorithm for fast locating triangles, which has the advantage of unique path and steady operation compared with other locating algorithms.2) Applying the theory of Constraint Delaunay Triangulation(CDT), the paper propounds the dynamical algorithm for constructing CDT, which insist that the constraint segments be inserted into the triangulation as soon as possible on the condition that they have been known already. Compared withthe traditional algorithm for constructing CDT, the dynamical algorithm exceeds the traditional algorithm in speed and dynamical expansion in data set. Furthermore, using the idea of the dynamical algorithm, the problem of eliminating the terrain points in road-design-face areas is masterly solved and the road integrated model is constructed.3) The 3D road model is so complicated that the calculation, the display and the storage of its scene would consume a large amount of time and space, which results in that the previous researches on 3D visual design of road is only confined to the description of the final design results and hard to merge into the design process. To solve this problem, the paper advances a dynamical view-dependent meshing method which can materialize dynamical view-dependent simplification and refinement of the integrate road model. The method can reduce the complexity of the model greatly on the condition that it ensures the realistic visual effect, and achieve the demand for real time visualization of the road 3D scene.4) Synthetically applying 3D special observation theory and realistic image drawing technology, the paper implements the dynamical exploring in the 3D realistic scenes based on the OpenGL technique. Moreover, based on the 3D observation theory, the paper develops a camera class which not only can give the 3D observation orders such as advancing, backing, turning to the left, turning to the right etc, but also obtain the view parameters such as the viewpoint location, the direction of view etc, which is important in view-dependent simplification of the integrated model.5) The paper discusses some crucial technologies for dynamical interaction in 3D scenes, and solves the problem of calculating the object space coordinate from the screen space coordinate, which lays down the foundation of real time spatial interaction. Based on OpenGL' s object selection technique, the real-time query of attribute information in 3D scenes is realized. Using 3D visualization and spatial query technologies, together combine...