Research On Rapid Geometric Processing Of UAV Images Of Island And Reef

The island and reef mapping is the cornerstone and gaurantee of national marine sovereignty, national security, and the implementation of marine development. This paper focuses on the application demand of island and reef mapping, utilizing the UAV remote sensing that has flexible, efficient and other technical advantages, combining with the characteristics of the island and reef, to research on UAV photography, image control point layout, extraction of Island and reef, aerial triangulation, DEM acquisition, ortho-rectification, image mosaic and other supplementary points. The main work and innovation points are as follows:1. The research background and significance, the current mainstream status and development trend of UAV remote sensing as well as the island and reef mapping are summarized. UAV photography and image control point layout plans suiting for the island and reef positioning are analyzed and designed.2. Upon analyzing the advantages and disadvantages of quadtrees, geodesic active contour model and Canny edge detector method used in the island coastal image segmentation, a new method by combining three of them is proposed.The experimental results show that the method proposed in this paper has the advantages of high speed, precision, reliability and automation etc., which can achieve automatic and precise extraction of results for weak edge which the boundary of water and land is not clear and the edge of severe depression.3. Considered the characteristics of UAV image of island and reef, an instant join points image matching method based on geometric constraint and spatial consistency is proposed. The method combines the advantages of SURF image matching of anti rotation,high speed and gray matching of high stability of the connection on multi-point extraction, to realize tie point image matching quickly and accurately, which lay the foundation for triangulation of UAV images of island and reef. Bundle triangulation method of UAV images under the waterline equal altitude constraint is proposed to improve the geometric positioning accuracy in island areas.4. The rapid geometric processing flow of UAV image for island and reef, and the corresponding system software are designed, and it is applied to practice in Huiyu Island, Fujian Province, which get superior results.