| CCD camera, has another name called digital camera. It is a new generation camera with the development of digital imaging technology. In recent years, CCD camera applies to close range photogrammetry and low altitude photogrammetry progressively. Whether the precision of photogrammetric results could meet the project request, depending on the technical parameter of the camera and data processing technical methods. So calibration of camera parameter is a key problem to guarantee result quality.According to the calibration of the ordinary non-metric digital camera, one commonly used method is the Direct Linear Transformation (DLT). Its basic thought is that establishing enough control points in 3D space, determining the space coordinates for each control point beforehand, taking the photography of the control point with the camera, and then leading the picture coordinates and the spatial coordinates into the DLT conformation equation, calculating inner and external elements of this camera. When considering lens distortion error, the system error must be added. Thus realizing the calibration correction of the camera host , the coordinates of the principal point as well as the system error because of the lens distortion . After many years'research analysis by many experts, the DLT calibration law already developed maturely, and the position precision of calibration results is already achieving 0.35 pixels. But this method needs to establish the high accuracy controlling field, bringing great inconvenience to the photographic field operation.Based on this reason, this article proposed one new camera calibration method without the object control,namely successive stereopairs relative orientation based on coplane condition, realizing the camera calibration to various parameters, and through the DLT model to examine the reliability of the camera calibration results. The experimental result indicated that, calibration method based on the coplane condition is reliable.
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