1. A system for extracting a road in an image, comprising: a first software module for extracting a plurality of line segments in said image; a second software module for determining orientations of said line segments; a third software module for pairing selected line segments based on said orientations, each line segment pair forming a candidate road segment; and a fourth software module for selecting some of said candidate road segments to connect together to form a road; a memory for storing said software modules; and a processor for executing said software modules.