Urban street grid description and verification

While two-dimensional maps exist for most urban areas, the descriptions may be incomplete or out of date, or of insufficient resolution for the given application and features such a roads are not described as 3-D objects. Most of the past work on road detection has concentrated on either low resolution, primarily rural roads (usually producing "spaghetti" roads with no notion of intersections), high resolution road following without the topological information of the intersections or pixel classification where there is no sense of the road as an object. This paper address the problem of extracting a street grid in an urban environment while maintaining the topological information of the intersections. Starting from an initial seed intersection, which gives the size and orientation of the expected grid this system uses a feature-based hypothesis and verify paradigm to extract a 3-D description of the street grid. The verification uses the context provided by an intersection model and by an extended street model and other available sensors.