Generalized camera calibration including fish-eye lenses
Generalized camera calibration including fish-eye lenses
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DOI：
10.1007/s11263-006-5168-1
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发表时间：
2006-07-01
影响因子：
19.5
通讯作者：
Gennery, Donald B.
中科院分区：
文献类型：
--
作者：
Gennery, Donald B.
描述了一种用于通过使用已知点（诸如从校准夹具测量的那些点）来精确校准包括径向透镜畸变的相机的方法。在单个最小二乘调整中校准内在参数和外在参数两者，但是规定在调整中包括内在参数的旧值。失真项是相对于光轴的，光轴被包括在模型中，使得它不必与图像传感器平面正交。这些失真项表示对基本透镜模型的校正，基本透镜模型是包括透视投影和理想鱼眼透镜作为特殊情况的概括。入射光瞳点的位置作为离轴角的函数也包括在模型中。(The包括所有这些效果的完整相机模型通常被称为CAHVORE。还描述了一种增加偏心失真的方法。先验标准偏差可以用于对失真项、光轴与传感器平面的垂线之间的差以及表示入射光瞳的移动的项的给定初始近似（其可以是零）应用权重，使得当校准数据中的信息不足时，很好地确定这些项的解。对于其他参数，非线性最小二乘平差所需的初始近似值以简单的方式从校准数据和其他已知信息中获得。（如果需要，也可以赋予这些权重。）通过基于残差分析的自动编辑，去除与其他数据过度不一致的校准点中的离群值。还描述了相机模型的使用，包括用于从对象空间传播到图像空间以及从图像空间传播到对象空间的偏导数。这些方法被用来校准火星探测漫游者上的相机。
A method is described for accurately calibrating cameras including radial lens distortion, by using known points such as those measured from a calibration fixture. Both the intrinsic and extrinsic parameters are calibrated in a single least-squares adjustment, but provision is made for including old values of the intrinsic parameters in the adjustment. The distortion terms are relative to the optical axis, which is included in the model so that it does not have to be orthogonal to the image sensor plane. These distortion terms represent corrections to the basic lens model, which is a generalization that includes the perspective projection and the ideal fish-eye lens as special cases. The position of the entrance pupil point as a function of off-axis angle also is included in the model. (The complete camera model including all of these effects often is called CAHVORE.) A way of adding decentering distortion also is described. A priori standard deviations can be used to apply weight to given initial approximations (which can be zero) for the distortion terms, for the difference between the optical axis and the perpendicular to the sensor plane, and for the terms representing movement of the entrance pupil, so that the solution for these is well determined when there is insufficient information in the calibration data. For the other parameters, initial approximations needed for the nonlinear least-squares adjustment are obtained in a simple manner from the calibration data and other known information. (Weight can be given to these also, if desired.) Outliers among the calibration points that disagree excessively with the other data are removed by means of automatic editing based on analysis of the residuals. The use of the camera model also is described, including partial derivatives for propagating both from object space to image space and vice versa. These methods were used to calibrate the cameras on the Mars Exploration Rovers.