两步投影法校正图像采集中的梯形畸变

图像采集中的梯形畸变是工程中最常见的畸变之一,但少有文献对此进行论述,为此文章提出一种简便的校正方法,在已知摄像机的镜头焦距和CCD大小的情况下,仅需要知道摄像机中轴线与地面(或被拍摄平面)的倾角一个参数,不需要控制点,就可以恢复原始图像.基本方法是利用小孔成像原理,先将CCD上的点投影到地面上,同时假设平行于地面一定高度有一虚拟CCD平面,再将地面上相应的点投影到虚拟CCD上,当所有点都遍历后,虚拟CCD平面上获得的图像就是梯形校正后的图像.实验证明,这种方法简洁有效,适应性强,效果理想,在工程上具有较高的应用价值.

A Rectification Method of Two-Step Projection for Trapezoidal Distortion on Image-Collecting

The trapezoidal distortion is one of the most common distortions on image collecting,but there are few literatures,which discussed it.Then,we present a rectification method for it.In the case of knowing the focal distance and the size of CCD,the only parameter needed to know to restore the image is the angle of the camera axis with the ground.And the algorithm needs no control point.First,a point on a real CCD is projected to the ground based on the pinhole model;second,in the same way,the point on ground is projected to a hypothetical CCD.When all the points are ergodic,the image on the hypothetical CCD is the restored image.Experimental results indicate that the algorithm proposed in this paper is strongly adaptable,effective and terse.It is comparatively valuable on engineering.