| This thesis studies the large-scale terrain modeling, road modeling, the fusion of terrain modeling and railway modeling, organization and management of the road 3D scene, interaction of 3D scene and other key technical problems, applied synthetically computer graphics, scientific computation visualization, human-computer interaction, data paging and dynamic scheduling technology, a three-dimensional real-time interactive visualization platform of the railway has been developed based on the 3D rendering engine OpenSceneGraph. The chief research contents and achievements could be summarized as follows:(1) Applied synthetically those methods of OpenSceneGraph geometric primitives modeling, pre-defined shape modeling and import models created by 3ds Max into scene achieved 3D models of the constructions of road, based on the idea of dividing and conquer.(2) Applied Virtual Planet Builder to build Multi-resolution paged terrain database based on QuadTree and pyramid model, dynamic scheduling terrain data to achieve smooth roaming in large-scale terrain scene.(3) The algorithm for the fusion of terrain modeling and railway modeling is put forward and realized. Search paged terrain database and restructure Constraint Delaunay Triangulation by terrain files which has overlap with the roadbed, and remove triangles in the overlay areas.(4) As a visual expression of 3D scene information, a hierarchical tree data structure was used to organize road 3D scene data, which accelerates the culling and collision detection and improve rendering efficiency.(5) In the light of those theories and algorithms stated in this thesis, a 3D real-time interactive visualization platform of the road has been developed based on the OpenSceneGraph. The platform with interactive roaming, scene editing and information query enables large-scale 3D scene of road rapid construction has been successfully applied in fields of project review and Comprehensive Information Management of engineering etc. |
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