由于航拍图像的拍摄高度远低于卫星图像拍摄高度，因此每个拍摄地点的建筑投影差大小和方向都不相同，图片畸变严重。此外，考虑到图像边缘区域的畸变程度远大于图像中心区域的畸变程度，本文提出了一种基于极坐标的Lagrange插值的逐点畸变校正方法。利用该方法在极坐标系内对单个像素点进行插值，然后根据插值结果对像素点进行校正，再将其坐标从极坐标系变换回直角坐标系，最后采用此方法在整个航拍图像内逐点进行畸变校正。实验结果表明，校正后的航拍图像畸变程度不超过3%，证明该方法不但能有效地校正畸变图像，且与传统的利用DLT线性求解畸变校正矩阵等校正方法相比具有更为广泛的适用性。

Since the height of aerial image shot is much lower than the height of satellite image shot, this may lead to the differences of the projection sizes and directions between every shooting location, which will result in serious picture distortion in most cases. In addition, the degree of distortion of the image edge region is much more serious than that in the center region, a distortion correction method based on Lagrange interpolation of polar coordinates has been proposed by this paper. We use this method to interpolate the single pixel in polar coordinates system. The pixel coordinate expression will be reconverted from polar coordinates to Cartesian coordinates after we corrected the pixel according the consequence of interpolation. And finally this method will be used to correct distortion pixel-by-pixel throughout the aerial image. The experiment results show that the corrected aerial image distortion does not exceed 3%, which proves that this algorithm can not only correct distortion image effectively, but also has a wide applicability compared with the traditional distortion correction methods, such as making use of the Direct Linear Transformation to obtain the distortion matrix.