相机检校的迭代处理方法

The Iterative Method of Camera Calibration

对相机光学畸变精确检校是提高摄影测量精度的手段之一。常规的相机检校方法一般是利用检校场,对相机检校模型的畸变系数进行估算进而校正相机畸变误差。由于引起各类相机畸变的原因千差万别,目前尚无法找到能对各类相机都适用的理想模型。为此,本文在对现有相机检校模型进行分析的基础上,提出了一种相机检校迭代处理的思路。首先,利用现有条件快速建立简易的室外检校场。其次,利用现有相机检校模型按照迭代处理的思路通过多次应用检校模型进行迭代检校来消除影像畸变。最后,在无控制点情况下,结合自由网平差理论进行无控制点的相机迭代检校处理。本文通过对两种非量测相机进行检校试验,比较分析了常规检校方法和迭代检校方法。试验结果表明,本文提出的相机检校迭代处理的思路能在常规检校方法的基础上进一步提高非量测相机检校的精度。

Accurate camera calibration is important for photogrammetric measurement.Traditional camera calibration methods are using the indoor/outdoor control fields and the effective camera calibration models to estimate the distortion coefficients.The various cameras have different distortions, so multi-camera calibration models are selected for calibration applications.It＇s desirable to find an ideal model that can be applied to most of cameras. Based on the analysis of the existing camera calibration models and methods, in this paper, a new camera calibration approach, named the iterative calibration method,is proposed.Firstly, a simple outdoor control field is established using the existing objects.Secondly,an iterative calibration method is described which applies the same or different models multiple times until the most distortions have been eliminated.Finally, combining the free network adjustment and the iterative method, camera calibration tests are carried out while no ground control points are available. Two non-metric cameras are tested and the results obtained using the traditional calibration method and iterative calibration method are analyzed. The experimental results show that the proposed camera iterative calibration method can further improve the camera calibration accuracy comparing to the traditional calibration method.