Due to the complex working environment, limited vision, and complicated crane operations, the crane operator faces two major problems when constructing with a crane: safety and working efficiency. Every year, numerous accidents occur, the majority of which are the result of the crane operator's inability to acknowledge hidden hazards. Some of these accidents can be effectively avoided through a comprehensive and intuitive display of important visual information to the crane operator. In this research, one of the most important safety-related visual information, namely the working area limit line, is provided on the acquisition of a crane's 3D spatial map based on a top-view camera. The purpose is achieved firstly by a real-time scene reconstruction of a visual simultaneously location and mapping approach semi-direct visual odometry and regularized monocular depth estimation. Then the working area limit line is shown on the top-view image according to the reconstructed 3D spatial map. The working area limit line can be successfully and precisely shown in the top-view image in both simulation and field experiments. The augmented top-view image with a working area limit line can help the crane operator notice the hidden hazards of outreaching the crane's working limit and improve the operation efficiency. The hazard of crane overturn can be effectively avoided with the displayed result. Based on the proposed approach, much more safety and operation related visual information can be displayed according to the 3D spatial map and classified operation stages in our future work.

由于工作环境复杂，视野受限，起重机操作复杂，起重机操作人员在使用起重机施工时面临两大问题：安全性和工作效率。每年都会发生多起事故，其中大部分是起重机操作员无法识别隐患造成的。通过向起重机操作员全面直观地显示重要的视觉信息，可以有效避免其中一些事故。在这项研究中，在基于顶视摄像头获取起重机的 3D 空间地图时，提供了与安全相关的最重要的视觉信息之一，即工作区域限制线。该目的首先通过视觉同时定位和映射方法半直接视觉里程计和正则化单目深度估计的实时场景重建来实现。然后根据重建的3D空间图在顶视图图像上显示工作区域限制线。在模拟和现场实验中，工作区域限制线都可以成功且精确地显示在顶视图图像中。带有工作区域限制线的增强顶视图可以帮助起重机操作人员发现超出起重机工作范围的隐患，提高作业效率。显示结果可有效避免吊车倾覆的危险。根据建议的方法，