Variables effecting photomosaic reconstruction and ortho-rectification from aerial survey datasets

Unmanned aerial vehicles now make it possible to obtain high quality aerial imagery at a low cost, but processing those images into a single useful document is not a seamless proces. Specifically, there are factors that must... [ view full abstract ]

Unmanned aerial vehicles now make it possible to obtain high quality aerial imagery at a low cost, but processing those images into a single useful document is not a seamless proces. Specifically, there are factors that must be taken into consideration when attempting to merge multiple images into a single coherent one. While ortho-rectification can be done, it tends to be expensive and time consuming. Image stitching offers a more economical, low-tech approach. However direct application tends to fail for low-elevation imagery due to one or more factors including insufficient lack of keypoints, parallax issues, and uniformity of the surveyed area. This paper discusses the problems and possible solutions when using techniques such as image stitching and structure from motion (SFM) for generating orthorectified imagery. These are discussed in terms of actual Irish projects including the Boland's Mills building in Dublin’s city centre, the Kilmoon cross farm survey, and the Richview buildings on the UCD campus. Implications for various Irish industries is explained in terms of both urban and rural projects.