Visual simultaneous localization and mapping (V-SLAM) has attracted a lot of attention lately from the robotics communities due to its vast applications and importance. This paper addresses the problem of V-SLAM with points and lines in particular scenes where there are many lines on an approximately planar ground. All the lines in these particular scenes are treated as 3D lines with four degree-of-freedom (DoF) in most V-SLAM systems with lines. However, lines on ground only have two DoF. The redundant parameters will increase the estimation uncertainty of lines on ground. In order to restrict the lines on ground to the correct solution space, we propose two parameterization methods for it. The first method still treats lines on ground as 3D lines, and then we propose a planar constraint for the representation of 3D lines to loosely constrain the lines to the ground plane. Further, to strictly constrain the lines on ground to the ground plane, the second method treats these lines as 2D lines in a plane, and then we propose the corresponding parameterization method and geometric computation method from initialization to bundle adjustment. After that, to better exploit lines on ground during localization and mapping by using the proposed parameterization methods, we propose the graph optimization-based monocular V-SLAM system with points and lines to deal with lines on ground differently from general 3D lines. Assisted by wheel encoders, the proposed system generates a structural map. We perform experiments on both simulated data and real-world data to demonstrate that the proposed two parameterization methods can better exploit lines on ground than 3D line parameterization method that is used to represent the lines on ground in the state-of-the-art V-SLAM works with lines.

视觉同时定位和制图（V-SLAM）由于其广泛的应用和重要性，最近引起了机器人界的广泛关注。本文解决了V-SLAM在特定场景中的点和线的问题，在这些场景中，大致平坦的地面上有多条线。在大多数带有线的V-SLAM系统中，这些特定场景中的所有线都被视为具有四个自由度（DoF）的3D线。但是，地面上的线路只有两个自由度。冗余参数将增加地面上线路的估计不确定性。为了将地面上的线限制在正确的解空间内，我们提出了两种参数化方法。第一种方法仍然将地面上的线视为3D线，然后为3D线的表示提出平面约束，以将线宽松地约束到地平面。此外，为了将地面上的线严格约束到地平面，第二种方法将这些线视为平面中的2D线，然后提出从初始化到束调整的相应参数化方法和几何计算方法。此后，为了通过使用建议的参数化方法更好地利用本地化和制图过程中的地面线，我们提出了一种基于图优化的单目V-SLAM系统，该系统具有点和线，以与一般3D线不同的方式处理地面线。在车轮编码器的协助下，拟议的系统生成了结构图。