Fast Construction Algorithm Of The Three-dimensional Road Network

As an indispensable part of the traffic network in the virtual 3D digital city,roads,interchanges,buildings and urban underpass tunnels are of great significance for the 3D simulation of the traffic,the optimization of road,vehicle tracking,traffic statistics and emergency treatment.This paper aims at establishing the 3D intelligent traffic simulation platform in digital city;combined with the physical structure and engineering characteristics of urban roads,overpasses,buildings and underpass tunnels,we use the two-dimensional grid maps of different levels to extract and construct the road,overpass and large-scale building groups,and urban underpass tunnels is constructed with the interactive parameterization method.(1)For the traditional and complex three-dimensional modeling,combined with the physical structure and engineering design characteristics of urban buildings and roads,select the two-dimensional grid maps of different levels as input data,automatically identify and extract the road centerline and building contours respectively,and further generate three-dimensional road,intersection and large-scale buildings.Overlapped three-dimensional totals are reconstructed by acquiring and detecting the overlapped of the edge lines of 3D road and building contours.(2)Aiming at the complicated spatial structure and modeling difficulties of the urban underpass tunnels,combined with the physical structure and engineering design characteristics of the tunnels,based on a set of control vertices,obtain the B-spline curves by interpolation to generate the urban underpass tunnel centerline,and then achieve the urban underpass tunnel centerline segmentation modeling,including the hole and hole body modeling.(3)Aiming at the problems of the complex modeling,large amount and variety of data in the 3D modeling of viaduct in digital city,first the centerlines of roads,the intersections and layers of the three-dimensional overpass are automatically extracted from the two dimensional grid map of local road network.Then the rapid three-dimensional solid modeling of the viaduct could be realized through the parametric modeling and texture mapping.The experimental results show that the parametric modeling method of roads,overpasses,large-scale buildings and urban underpass tunnels under the three-dimensional road network can greatly reduce the modeling time,and improve the design efficiency with better flexibility and interactivity.