使用雷射墨線儀來校正魚眼攝影機

Abstract

最近有許多應用使用到魚眼攝影機，例如車週影像系統、停車場停車導引系統。由於魚眼攝影機可以提供大約180度以上的視野範圍，所以它非常適用於上述大場域的應用。然而，魚眼攝影機所拍攝的影像具有嚴重的徑向失真。失真的影像對人類視覺而言很不自然。因此，消除魚眼影像的徑向失真是一個重要的課題。本論文提出了一種使用可以容易取得的雷射墨線儀來校正魚眼攝影機的方法，其中使用雷射墨線儀投射出的雷射線和攝影機的成像幾何估測出影像中心和量測用於校正徑向失真的資料。最後魚眼影像與透視投影之間的幾何關係即可被用來反扭曲魚眼影像。

Recently, fish-eye cameras are used in many applications such as around vehicle monitoring system and parking guidance. A fish-eye camera can support very large field of view, up to 180 degrees or more, and is very suitable for above applications for large areas. However, an image captured by fish-eye camera impaired with severe radial distortion. Distorted images are very unnatural for human to perceive. Therefore, it is an important issue to eliminate the radial distortion of a fish-eye image. In this thesis, a novel fish-eye camera calibration method based on an off-the-shelf laser level is proposed, which estimates the principal point and measures the data for correcting radial distortion by using the relationship between laser lines projected by a laser level and imaging geometry of a camera. Finally, the geometric relation between a fish-eye image and perspective projection can be applied to de-warp the fish-eye image.