<title>Real-time road detection in infrared imagery</title>

Abstract

Automatic road detection is an important part in many scene recognition applications. The extraction of roads provides a means of navigation and position update for remotely piloted vehicles or autonomous vehicles. Roads supply strong contextual information which can be used to improve the performance of automatic target recognition (ATh) systems by directing the search for targets and adjusting target classification confidences. This paper will describe algorithmic techniques for labeling roads in high-resolution infrared imagery. In addition, realtime implementation of this structural approach using a processor array based on the Martin Marietta Geometric Arithmetic Parallel Processor (GAPPTh) chip will be addressed.The algorithm described is based on the hypothesis that a road consists of pairs of line segments separated by a distance "d" with opposite gradient directions (antiparallel). The general nature of the algorithm, in addition to its parallel implementation in a single instruction, multiple data (SIMD) machine, are improvements to existing work.The algorithm seeks to identify line segments meeting the road hypothesis in a manner that performs well, even when the side of the road is fragmented due to occlusion or intersections.The use of geometrical relationships between line segments is a powerful yet flexible method of road classification which is independent of orientation. In addition, this approach can be used to nominate other types of objects with minor parametric changes. INTRODUCTIONTo begin nomination of potential road areas, an edge operator is used to extract the edges1'2'3. The edges are then partitioned into line segments and attributes such as length, midpoint coordinates, direction4, and slope are calculated. That information is then arranged in an adjacency matrix5 type of format. The relationships between line segments such as the distance between midpoints, the difference in slope, etc., can then be evaluated. A set oftwo line segments are part of a potential road if they meet the following criteria: