Abstract: Because of the low relative altitude of UAV, ground fluctuation will have an adverse effect on the resolution, coverage and overlaps of UAV images when using UAV for aerial photography of surveying and mapping. There will be some defects in the aerial images, such as insufficient resolution, insufficient overlap, coverage loopholes and so on. In order to solve this problem, this paper proposes a method to calculate the coverage of each image accurately with the help of DEM by using digital differential correction, and uses FME to efficiently generate the coverage of all images. It is verified by some pracise project that the method can accurately predict the coverage and overlap of all images in the the designed air routes. So the design defects can be found and corrected in time. This method can effectively reduce the image coverage defects caused by terrain undulation, so as to avoid rework and improve the efficiency of aerial photography.

Key words: terrain fluctuation, UAV, aerial photography, image coverage analysis, FME