Improvement on the Process of Cadastral Map Resurveying Using UAS Photogrammetry

In many areas of Taiwan, there are still used graphically digitized cadastral maps. Due to poor precision and environmental changes, there are often inconsistencies in the application. There are two ways to update cadastral maps: cadastral map resurveying and cadastral rearranging. The purpose is to redraw the cadastral map and calculate the area so that the location, shape, place number, and area of each land are consistent with the contents of the register. Currently, the cadastral resurveying method is adopted. However, due to financial and manpower problems, there are still many areas where cadastral maps cannot be updated. In this study, the Miaoli county cadastral resurveying area was used as the experimental area. Using the UAS aerial survey to obtain the true orthophoto image overlay cadastral map, it was explored whether UAS aerial survey could improve the current cadastral map resurveying process. All experimental data in this study were compared with the data of the current cadastral retesting procedure, confirming that UAS aerial survey can improve the following, 1. Assist in cadastral surveys and results announcements to reduce public concerns about resurvey results. 2. Improve image efficiency and correctness by image-assisted area analysis. After comparing the image measurement area and the registered area of each piece of land, the maximum difference is 0.8276 square meters still within the regulation margin. 3. The ground measurement work can be replaced by the image point coordinate measurement. 4. The cadastral boundary line after the area analysis can be converted into a new cadastral map.