Vision-based Localization from Three-Line Structures （TLS）

This paper presents a novel vision based localization algorithm from three-line structure (TLS). Two types of TLS are investigated: 1) three parallel lines (Structure I); 2) two parallel lines and one orthogonal line (Structure II). From single image of either structure, the camera pose can be uniquely computed for vision localization. Contributions of this paper are as follows: 1) both TLS structures can be used as simple and practical landmarks, which are widely available in daily life; 2) the proposed algorithm complements existing localization methods, which usually use complex landmarks, especially in the partial blockage conditions; 3) compared with the general Perspective-3-Lines (P3L) problem, camera pose can be uniquely computed from either structure. The proposed algorithm has been tested with both simulation and real image data. For a typical simulated indoor condition (75 cm-size landmark, less than 7.0 m landmark-to-camera distance, and 0.5-pixel image noises), the means of localization errors from Structure I and Structure II are less than 3.0 cm. And the standard deviations are less than 3.0 cm and 1.5 cm, respectively. The algorithm is further validated with two actual image experiments. Within a 7.5 m×7.5 m indoor situation, the overall relative localization errors from Structure I and Structure II are less than 2.2％ and 2.3％, respectively, with about 6.0 m distance. The results demonstrate that the algorithm works well for practical vision localization.

Vision-based Localization from Three-Line Structures (TLS)