In addition to continuous or interrupted bright lines indicating lateral lane boundaries, other bright marks are painted occasionally onto a lane, for example arrows indicating obligatory driving directions (straight ahead, compulsory right turn, etc.), signs indicating that stopping or parking is prohibited, special lanes for buses or bicyclist, etc. Although such symbols are normed, it has been observed that the actually painted road mark frequently does not (fully) conform to the norm. Recognition of such symbols within a DSS thus constitutes a problem which has rarely been addressed by CV in vehicles.
A multitude of shapes will have to be handled although it should be possible to adapt methods from workpiece recognition on conveyor belts for these recognition tasks. The problem is aggravated in heavy traffic if parts of a road marking are occluded by other vehicles such that a virtual image of a marking has to be built by concatenating successively visible parts.
Practically nothing has been published about the detection and tracking of lane marks constituted by rows of reflectors nor have difficulties been treated which arise when - possibly only temporarily - irrelevant lane markings have not been completely removed or are superseded by new ones in a different color (for example yellow instead of white).