# Progressive Dynamic Registration Method for Tile Maps Based on Optimum Multi-Features
## 4 Experimental Results and Applications
### Method Accuracy Verification and Comparison  
Taking the Amap as the map to be registered and the Tianditu as the target map, register the different areas of the remote sensing maps and the vector maps, and calculate the root mean square error (RMSE) of the results. RMSE is defined as follows:  
\[\text{RMSE}=\sqrt{\frac{\sum_{i=1}^{n}\left(\left(x_{i}-x_{i}^{\prime}\right) ^{2}+\left(y_{i}-y_{i}^{\prime}\right)^{2}\right)}{n}} \tag{4}\]  
In the above formula, n represents the number of corresponding points, \((x_{i},y_{i})\) represents the pixel coordinates of the ith corresponding point in the target image, \((x_{i}^{\prime},y_{i}^{\prime})\) represents the pixel coordinates of the ith corresponding point in the image to be registered. Map features are important factors affecting the registration accuracy. To test the registration accuracy of PDR in different regions, three different types of regions were selected as the study objects, with Beijing city as a representative of large cities, Ganzhou city as a representative of small and medium-sized cities, and Shaxi Town as a representative  
Figure 6: Results after feature surfaces matching filtering. of rural areas. Beijing City is the capital of China, with a regular and complex urban road network. The coordinates of the center of Beijing are [116.39, 39.92]. Ganzhou City is a prefecture-level city in Jiangxi Province. Zhangshui river passes through the center of the city. The features of the image are obvious. The geographical coordinates of the city's center are [114.94, 25.83]. Shaxi Town is located in Yongfeng County, Ji'an City, Jiangxi Province. It belongs to a semi-mountainous and semi-hilly area. Most of the images are forests. The vector map is mainly road lines, and the geographical coordinates are [115.59, 26.88]. In urban areas, the maximum zoom level of remote sensing images of the Amap and Tianditu can reach 18 levels. In nonurban areas, the highest map scale of Amap is level 16, and the highest map scale of Tianditu is up to level 18. Taking Tianditu scale 12 as an example, Figure 7 shows the remote sensing images and vector map images of the two regions. For the multiscale maps of the two regions, we compare the RMSE of the PDR method, the SURF+RANSAC method, and the coordinate system conversion method. Tables 1-6 show the RMSE and the calculated offset values when using the three methods for registration at multiple scales. \"/\" means there are no data in this scale, and \"\(\times\)\" means the registration method fails in this scale. Table 7 shows the average RMSE of the three methods on remote sensing maps of Beijing City, remote sensing maps of Ganzhou City, remote sensing maps of Shaxi Town, vector maps of Beijing City, vector maps of Ganzhou City, and vector maps of Shaxi Town. The average RMSE of the PDR method is less than 2.5 in all three areas of remote sensing maps and vector maps, which have good stability and accuracy that can meet the needs of actual use. Figure 7: Cont. Figure 7: Remote sensing maps and vector maps of Tanditu Beijing, Ganzhou and Shaxi. **(a)** Remote sensing map of Beijing. **(b)** Remote sensing map of Ganzhou. **(c)** Remote sensing map of Shaxi. **(d)** Vector map of Beijing. **(e)** Vector map of Ganzhou. **(f)** Vector map of Shaxi.