  How to automatically generate a realistic large-scale 3D road network is a
key point for immersive and credible traffic simulations. Existing methods
cannot automatically generate various kinds of intersections in 3D space based
on GIS data. In this paper, we propose a method to generate complex and
large-scale 3D road networks automatically with the open source GIS data,
including satellite imagery, elevation data and two-dimensional(2D) road center
axis data, as input. We first introduce a semantic structure of road network to
obtain high-detailed and well-formed networks in a 3D scene. We then generate
2D shapes and topological data of the road network according to the semantic
structure and 2D road center axis data. At last, we segment the elevation data
and generate the surface of the 3D road network according to the 2D semantic
data and satellite imagery data. Results show that our method does well in the
generation of various types of intersections and the high-detailed features of
roads. The traffic semantic structure, which must be provided in traffic
simulation, can also be generated automatically according to our method.
