## 4 Comprehensive Performance Evaluation
### Indoor Environment
#### 4.1.2 Mapping  
1. LiDAR SLAM mapping analysis  
The robot trajectory is illustrated by the colored line is shown in Figure 6, which presented from a top-view perspective of the LiDAR SLAM mapping result, the yellow point cloud denotes the lowest elevation corresponding to the floor, while the red point cloud represents the highest elevation corresponding to the ceiling. The central point cloud in the map captures reflections from exterior high-rise objects encountered when traversing corridor windows. After completing a circuit around the building, it is observed that the 3D reconstructed map of LiDAR SLAM presents the architectural structure of the indoor environment in a comprehensive geometrically precise manner. However, when viewed locally, the map exhibits sparser details and there is a lack of discernibility on planar features. Figure 5: I3 RPE with regard to the translation part (m) for delta = 1 (frames) using consecutive pairs (with SE(3) Umeyama alignment, while processing panning rotation and scale): (**a**) ORB-SLAM3 with loop closure; (**b**) SC-LeGO-LOAM with loop closure; (**c**) ORB-SLAM3 without loop closure; and (**d**) SC-LeGO-LOAM without loop closure. Visual SLAM based on two mapping methods  
Figure 7 depicts local reconstructed maps based on the ground truth or ORB-SLAM3 within a depth range of 7 m, with the reconstruction areas and perspectives corresponding to the white field of view (FOV) trapezoids and arrows labeled (1) and (2) in Figure 6.  
Figure 6: A top-view perspective of the LiDAR SLAM mapping result. The colored point clouds depict the robot’s poses. The white boxes represent specific scenarios: (1.) Multiple corners. (2.) Extended corridor. Figure 7: Local reconstructed indoor maps within a depth range of 7 m. (**a**) The first perspective (1) based on ground truth; (**b**) The first perspective (1) based on ORB-SLAM3; (**c**) The second perspective (2) based on ground truth; (**d**) The second perspective (2) based on ORB-SLAM3. Firstly, a comparison of the 3D reconstruction effects between the two Visual SLAM mapping approaches is performed. In the first perspective, Figure 7a,b, the reconstruction from ORB-SLAM3, exhibits multiple image overlap phenomena on the fire hydrant on the wall, the door in the background, and the window frame on the right wall. This results in distorted and shifted object shapes. In contrast, the reconstruction based on the ground truth appears more detailed, continuous, and visually superior, closely aligning with the actual scene. Moving to the second perspective within the indoor environment, Figure 7c,d, the fire extinguisher on the wall and its signage similarly appear more blurred in the reconstruction from ORB-SLAM3, consistent with the issues observed in the previous location. This problem arises from the differences in data sources and algorithms between the ORB-SLAM3 and Cartographer models. ORB-SLAM3 calculates camera poses based on feature point matching for each image, leading to cumulative errors in the \(z\)-axis direction due to robot vibrations during movement. This results in discontinuous height differences in the overlay of each frame during mapping. In contrast, the Cartographer model utilizes 3D LiDAR data with wheel odometry for calculation, imposing fixed constraints on the pose in the \(z\)-axis direction. This ensures consistency in height along the \(z\)-axis in the ground truth, resulting in a smoother overlay of each frame during mapping. 3. Comparison between LiDAR SLAM and Visual SLAM  
In this section, we compare Visual SLAM and LiDAR SLAM mapping based on three aspects. The first aspect to be discussed is the ability to identify items. In Figure 7, the map constructed by Visual SLAM displays more detailed and rich surface features. For example, the fire hydrant on the wall surface and the colors of surrounding objects are reconstructed, enhancing map identifiability and closely resembling the real scene. In contrast, the LiDAR SLAM reconstruction only outlines the structural aspects of the environmental architecture.