# Semi-Automatic Method of Extracting Road Networks from High-Resolution Remote-Sensing Images
## 2 Materials and Methods
### Methodology
#### 2.2.1 Interactive Single-Road Extraction
Among these algorithms, the implementation of new algorithms such as endpoint modifications, road connections, and road network generation algorithms was crucial for establishing the whole road-extraction workflow. Four high-resolution images

Figure 18: Comparison of intersections with auxiliary roads: (**a**) original image; (**b**) extraction result; (**c**) ground truth. with different terrains and resolutions are used to validate the proposed framework, and the results show that the strategy greatly improves the road network extraction effect. It has good accuracy and universality and can be used to perform road extraction and road network update with high-resolution remote-sensing images. The evaluations of the extraction results of the four images show that the road precision and IoU both reach a high level. At the same time, the developed method has better precision and faster speed than the semi-automatic method. Additionally, because of the wide universality, the proposed method has great potential in data labeling. Lastly, experiments also show that this strategy does not consider some special road types and may miss extraction of shorter roads, which deserve more attention in future work. Conceptualization, W.C. and K.Y. ; methodology, K.Y. and W.C.; software, K.Y. and S.S.; investigation, K.Y., Y.L. ([PERSON]) and Y.L. ([PERSON]); writing, K.Y. and W.C.; writing--review and editing, W.C., K.Y. and M.G. ; funding acquisition, W.C. All authors have read and agreed to the published version of the manuscript. Not applicable. The aerial image data used to support the findings of this study were supplied by the High-Resolution Comprehensive Traffic Remote-Sensing Application program under grant No. 07-Y30B10-9001-14/16, thus cannot be made freely available. Similarly, the GF-2 satellite image data used to support the findings of this study were provided by the Innovation Fund Project of CETC key laboratory of aerospace information applications under grant No. SXX19629X060, and so cannot be made freely available. The authors are grateful to [PERSON], [PERSON], [PERSON] and [PERSON], who provided assistance and advice during various stages of this work. The authors declare no conflict of interest. ## References

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