Vanishing Points

Sets of parallel lines in 3-D space are projected into a 2-D image to a set of concurrent lines. The meeting point of these lines in the image plane is called a vanishing point. It can belong to the line at infinity of the image when the 3-D lines are parallel to the image plane. Even though concurrence in the image plane does not necessarily imply parallelism in 3-D, the counterexamples for this implication are rare in real images. Thus, the problem of grouping sets of parallel lines in 3-D is reduced to finding significant sets of concurrent lines in the image plane.

In this chapter we will explain how vanishing points can be reliably and automatically detected with a low number of false alarms (NFA) and a high precision level without using any a priori information on the image or calibration parameters and without any parameter tuning. On the contrary, a vanishing point detector can be used to determine some calibration parameters of the camera or for other applications such as single-view metrology.