3D Alignment Design System for Urban Rail Transit Base on Virtual City and BIM.

The essential requirement of alignment design system includes integration of massive geographic information, various modes of interactive operation, multiple expression and observation manners for alignment scheme. This paper sets up a 3D virtual city through an open source toolkit named osgEarth; integrates various GIS data affecting route scheme inside a 3D virtual scene after process; proposes a dynamic modeling method for objects in virtual city scene; supplies approaches to edit horizontal and vertical alignments through interaction interface of the scene and QT view framework. Based on stretch method from cross section of structures, the proposed technique could create simplified BIM models of subgrade, bridge, and tunnel to express the design idea of alignment engineer. Benefit of the compatibility of 3D modeling files, the complicated station models could be rendered. The scene efficiency is improved by LOD technique. The research results show that the proposed 3D alignment design system could make sure the rendering fluency after multi-source data integration in the scene, and could realize synchronous 3D design for many projects and schemes. [ABSTRACT FROM AUTHOR]