## 4 Experiment Results and Discussion
The Epson and CPT sensors showed error magnitudes in the range of 0.48 m to 0.85 m. The InvenSense MEMS sensor produced a mean error of 1.13 m.  
It is evident that the slice size did not significantly impact the accuracy assessment mean values. A comparison of the results in Tables 3 and 4 reveals that the 5 and 10 s slice lengths provide very similar mean error values. The differences are on the order of a few centimeters, which are not significant in relation to the overall magnitude of the mean errors themselves. The differences in mean error values can be attributed to differences in the point cloud shapes for different slice sizes, which slightly impacts the quality of registration for each slice. For a better visualization of the accuracy assessment results, Figure 6 shows color maps of the error values for the six point clouds and 5 s slice size length. Both color and the size of the data markers indicate the error magnitude for each slice. The points are plotted at the centroid of each individual slice (c.f. Figure 5b). In general, the navigation  
Figure 7: Color maps of accuracy assessment for 10 s slice length (marker size and color indicate error magnitude): (**a**) InvenSense; (**b**) Epson_1; (**c**) Honeywell_1; (**d**) Epson_2; (**e**) Honeywell_2; (**f**) Epson_3. Note that the coordinates have been reduced to a local system for display clarity. accuracy of a mobile mapping system changes slowly at different points in time. Except for the InvenSense sensor, which is a lower grade of MEMS IMU, a smooth transition of error values from one slice to the next is generally evident, as can be seen in Figure 6. Similar observations are valid for experiments with slice size of 10 s (Figure 7). However, it was observed during testing that the smaller the slice size produced better the alignment following the registration. Accordingly, the accuracy assessment results from the 5 s slices are assumed as the more representative of the accuracy for the three sensors. Multiple datasets were captured on separate dates with both the Epson and Honeywell sensors. Inspection of the results in common areas of the test field (Figure 7) reveals overall consistency of the results for both. Some local differences in accuracy do exist, in the vicinity of x = 100 m and y = 0 m, for example. These can be attributed to different satellite visibility conditions, as can other localized accuracy differences that can be seen between different sensors. Comparison of Table 2 with the results in Tables 3 and 4 reveals that the MMS errors as determined by the proposed method are largely due to the low-cost IMUs rather than the Velodyne data. In fact, the new accuracy assessment methodology provides slightly more optimistic results than what is indicated by the trajectory difference statistics. Further demonstration of the performance of the proposed method is given in Figure 8. This figure shows an example of point cloud cross-sections before and after registration. As can be seen, the ICP method provided precise alignment between the kinematic and static point clouds following the registration, even for point clouds that were significantly (\(\sim\)1 m) separated in three dimensions. This provides high confidence in the results of the proposed accuracy assessment methodology. MMSs. Opportunumity also exists to extend the testing to other types of navigation sensors and laser scanners. Conceptualization, K.A.-D., D.D.L., E.K. and R.D. ; methodology, K.A.-D., D.D.L. and E.K. ; software, K.A.-D.; validation, K.A.-D.; formal analysis, K.A.-D. and D.D.L. ; investigation, K.A.-D. and D.D.L. ; resources, R.D. ; data curation, K.A.-D.; writing--original draft preparation, K.A.-D. and D.D.L. ; writing--review and editing, K.A.-D., D.D.L., E.K. and R.D. ; visualization, K.A.-D.; supervision, D.D.L. and R.D. ; project administration, D.D.L. ; funding acquisition, D.D.L. All authors have read and agreed to the published version of the manuscript. This research was funded by NovAtel. Not applicable.