Firstly, this paper compares and analyses the matching results of models I, Cr, and Cv. The similarity metrics shared by these three models are length, direction, and Hausdorff distance, and the differences are that the three models combine ISOD descriptors, pinch chain codes, and curvature variance, respectively. The output graph and data of the comprehensive measurement model combining four similarity measures are shown in Table 6, Table 7, and Fig. 6, and are compared and analyzed by comparing the distribution and evaluation metrics of mismatched roads and target roads.
Table 6
Evaluation results of Models I, Cr, and Cv in Experiments A
Matching Models
|
Precision(%)
|
Recall(%)
|
F-score值(%)
|
Models I
|
86.39
|
94.06
|
90.06
|
Models Cr
|
85.15
|
89.55
|
89.29
|
Models Cv
|
76.60
|
91.25
|
83.29
|
Table 7
Evaluation results of Models I, Cr, and Cv in ExperimentsB
Matching Models
|
Precision(%)
|
Recall(%)
|
F-score值(%)
|
Models I
|
94.75
|
93.34
|
94.04
|
Models Cr
|
95.20
|
92.98
|
94.08
|
Models Cv
|
86.48
|
86.46
|
86.47
|
In the matching experiments in Group A, all three models have higher check-full rates than check-accurate rates. With the three common indicators unchanged, model I combined with ISOD has the highest F-score value, i.e., the best matching effect. The scale of the reference roads in Group A is 1:250,000, and due to the small scale, most of the roads are main roads, and a very small portion of them are branch roads. As shown in the derived graphs, the mis-matching cases are mainly distributed in main roads, and the mis-matches are mainly distributed in branch roads. In the matching experiment of group B, the detection rate of all three models is higher than the detection rate. In the case that the three indicators remain unchanged, the model Cr combined with the angle chain code has the highest F-score value, i.e., the matching effect is the best. The scale of the reference road in Group B is 1:50,000 (a larger scale), the road display is more detailed, and the zoning of the trunk road and the reference road is significant. The mis-matching is mainly distributed in the branch road, and incorrect matching is mainly distributed in the trunk road. When matching between small-scale road datasets, we can consider combining spatial relationship indicators based on geometric similarity indicators, i.e., ISOD descriptors, to match road datasets, creating a better matching effect. When matching between large-scale road datasets, the geometric similarity index can be considered to be combined with the angle chain code, and the matching effect is better.
Subsequently, this paper outputs the output plots of the matching results of the integrated metric models—ICr, ICv and CrCv—which combine the five similarity metrics and data (shown in Table 8, Table 9 and Fig. 7), performing comparative analyses by comparing the distributions of the mis-matched roads among the target roads, as well as evaluating the metrics.
Table 8
Evaluation results models ICr, ICv and CrCv in Experiments A
Matching Models
|
Precision(%)
|
Recall(%)
|
F-score value(%)
|
Models ICr
|
76.81
|
87.35
|
81.74
|
Models ICv
|
81.96
|
93.06
|
87.16
|
Models CrCv
|
82.73
|
89.48
|
85.97
|
Table 9
Evaluation results models ICr, ICv and CrCv in gExperiments B
Matching Models
|
Precision(%)
|
Recall(%)
|
F-score value(%)
|
Models ICr
|
94.91
|
93.06
|
93.98
|
Models ICv
|
88.86
|
88.76
|
88.81
|
Models CrCv
|
90.81
|
90.01
|
90.41
|
In the road dataset matching experiments in Group A, the models—ICr, ICv, and CrCv—all have higher check-perfect rates than check-accurate rates. The model ICv combining ISOD descriptors and curvature variance has the highest F-score value, i.e., the best matching effect, when the three metrics in common are unchanged. Mis-matches are mainly distributed on trunk roads, while mis-matches are more evenly distributed on trunk and branch roads, but mis-matches are more concentrated in areas with dense branch roads. In the road dataset matching experiments in group B, the check accuracy rates of models—ICr, ICv, and CrCv—are all higher than the check accuracy rate and the model ICr, which combines the ISOD descriptor. The angle chain code has the highest F-score value, i.e., it has the best matching effect, while the three shared metrics remain unchanged. Mis-matches are distributed in both main roads and branch roads, while incorrect matches are mainly distributed in branch roads.
When performing the matching of small-scale road datasets while keeping length, distance, and direction constant, the combination of ISOD descriptor and curvature variance can be considered for matching since it has the best matching effect. When matching large-scale road datasets, the ISOD descriptor and the angle chain code has the best matching effect. Spatial relationships can used for the matching of both large-scale or small-scale road datasets since the matching effect is more accurate.
Table 10
Evaluation results of Model ICrCv in Experiments A
Matching Models
|
Precision(%)
|
Recall(%)
|
F-score value(%)
|
Models ICrCv
|
83.57
|
90.17
|
86.74
|
Table. 11 Evaluation results of Model ICrCv in Experiments B
Matching Models
|
Precision(%)
|
Recall(%)
|
F-score value(%)
|
Models ICrCv
|
91.01
|
90.54
|
90.27
|
Subsequently, the matching results of the model ICrCv in Groups A and B experiments are compared and analysed in this paper (as shown in Table 10, Table 11 and Fig. 8). With the increase of similarity index, the matching model is more constrained for road matching, and ISOD descriptors, pinch chain codes and curvature variance are added at the same time while keeping the distance, length and direction unchanged. By comparing the matching results, the model is more suitable for road matching between large-scale road datasets. In Group A experiments, mis-matching cases are distributed in the main roads and incorrect matching cases are mainly distributed in the branch roads. In Group B experiments, the mis-matches are mainly distributed in branch roads. Incorrect matches are distributed in both main roads and branch roads, and these matches are more concentrated in areas with dense branch roads.
Ultimately, this study compares the matching results of the seven models in the two groups of road datasets and analyses the matching results in terms of the precision, recall, and F-score values. The overall matching results for the road datasets in Groups A and B are shown in Tables 12 and 13.
Table 12
Matching results of Group A road dataset
Matching Models
|
FN
|
FP
|
TP
|
Precision(%)
|
Recall(%)
|
F-score(%)
|
Models I
|
69
|
172
|
1092
|
86.39
|
94.06
|
90.06
|
Models Cr
|
105
|
157
|
900
|
85.15
|
89.55
|
89.29
|
Models Cv
|
102
|
325
|
1064
|
76.60
|
91.25
|
83.29
|
Models ICr
|
129
|
269
|
891
|
76.81
|
87.35
|
81.74
|
Models ICv
|
83
|
245
|
1113
|
81.96
|
93.06
|
87.16
|
Models CrCv
|
107
|
190
|
910
|
82.73
|
89.48
|
85.97
|
Models ICrCv
|
102
|
184
|
936
|
83.57
|
90.17
|
86.74
|
Table 13
Matching results of Group B road dataset
Matching Models
|
FN
|
FP
|
TP
|
Precision(%)
|
Recall(%)
|
F-score(%)
|
Models I
|
582
|
452
|
8158
|
94.75
|
93.34
|
94.04
|
Models Cr
|
602
|
402
|
7971
|
95.20
|
92.98
|
94.08
|
Models Cv
|
1148
|
1146
|
7333
|
86.48
|
86.46
|
86.47
|
Models ICr
|
598
|
430
|
8021
|
94.91
|
93.06
|
93.98
|
Models ICv
|
965
|
955
|
7620
|
88.86
|
88.76
|
88.81
|
Models CrCv
|
843
|
769
|
7598
|
90.81
|
90.01
|
90.41
|
Models ICrCv
|
804
|
760
|
7695
|
91.01
|
90.54
|
90.27
|
As shown in Fig. 9, Group A matching experiments were conducted on road datasets with scales of 1:250,000 and 1:50,000, where Model I, Model Cr and Model ICrCv had higher checking accuracy rates of 86.39%, 85.15% and 83.57%, respectively, with Model 1 having the highest checking accuracy. Model I, Model Cv and Model ICv had higher check accuracy rates of 94.06%, 91.25% and 93.06%, respectively. Among these, Model I had the highest check accuracy rate. In Group A experiments, all seven groups of experimental results had lower check accuracy than check completeness. As a result, Model I has the best matching effect when performing matching between small-scale road datasets. In other words, the comprehensive similarity model consisting of four similarity indicators—distance, direction, length and ISOD descriptor—was applied to match roads between small scales, and its check-perfect rate was higher than the check-accurate rate, i.e., the cases of mis-matches were lower than the cases of incorrect matches.
This study also evaluates and analyses the matching results of Group B road datasets. As shown in Fig. 10, in performing the matching of Group B with scales of 1:50,000 and 1:10,000, Model I, Model Cr and Model ICr had higher checking accuracy rates of 94.75%, 95.20% and 94.91%, respectively, with Model Cr having the highest checking accuracy. Model I, Model Cr and Model ICr had higher detection rates of 93.34%, 92.98% and 93.06%, respectively, with Model I having the highest detection rate. Since the highest checking accuracy and the highest checking completeness are not from the same matching model, they need to be combined with the F-score value for further quality evaluation. In the Group B experiment, all seven groups of matches passed through the check accuracy rate higher than the check completeness rate.
As shown in Fig. 11, among the seven sets of experiments in Group A, Model I had the highest F-score value of 90.06%, and Model Cr had the next highest F-score value of 89.29%. Among the seven sets of experiments in Group B, Model Cr had the highest F-score value of 94.08%, and Model I had the second highest F-score value of 94.04%. In summary, when matching between road datasets, a comprehensive similarity metric model that combines length, Hausdorff distance, direction and ISOD descriptors can be used for matching, and its comprehensive matching effect is the best. Overall, the matching effect of all seven matching models in large-scale road datasets is better than that of small-scale road datasets. Therefore, the larger the scale of the road dataset, the better the effect of matching using the comprehensive similarity model.
With the rapid development of society and the economy, various fields are implementing increasingly higher requirements for the quality and availability of road data. As an important part of geospatial information, the accuracy and real-time performance of road data are crucial for urban planning, traffic management, disaster emergency response, and other fields. In this experiment, based on three geometric similarity indicators—length, Hausdorff distance and direction—ISOD descriptor, angle chain code, and curvature variance are combined to construct a comprehensive similarity metric model for multi-scale road matching experiments at scales of 1:10,000 and 1:50,000, as well as 1:50,000 and 1:250,000. By comparing the results of the experiments, it is found that the matching effect on the large-scale road network is better than that of the small-scale road network matching as a whole, which is because the large-scale road network has more detailed and precise road information and provides more road matching points. In the same set of experiments, with the change in the number of model indicators, the overall matching effect will also change since the model needs to consider changes in information complexity. The experiments found that the comprehensive similarity metric model constructed through multiple indicators can more accurately reflect the actual characteristics of the road to improve matching accuracy. Due to the complexity and diversity of road data sources, the use of integrated evaluation models reduces the reliance on a single indicator, improves robustness, and is more adaptable to different environments.
This experiment is based on three geometric metrics, and innovatively integrates three metrics—ISOD descriptor, angle chain code and curvature variance—to construct a fusion model with several different metrics, enriching the comprehensive similarity metric modelling approach in the field of multi-scale road matching. However, there are also shortcomings in this experiment. Although two new metrics are introduced, the complexity of the matching process increases along with the increase in the number of model metrics, which reduces the efficiency of matching. In addition to this, the selection of metrics for evaluating the model is a challenge. How to effectively fuse the information of different metrics and the different matching methods may have a significant impact on the results.