A minimal solution using two affine correspondences is presented to estimate the common focal length and the fundamental matrix between two semi-calibrated cameras - known intrinsic parameters except a common focal length. To the best of our knowledge, this problem is unsolved. The proposed approach extends point correspondence-based techniques with linear constraints derived from local affine transformations. The obtained multivariate polynomial system is efficiently solved by the hidden-variable technique. Observing the geometry of local affinities, we introduce novel conditions eliminating invalid roots. To select the best one out of the remaining candidates, a root selection technique is proposed outperforming the recent ones especially in case of high-level noise. The proposed 2-point algorithm is validated on both synthetic data and 104 publicly available real image pairs. A Matlab implementation of the proposed solution is included in the paper.

本文提出了一种仅使用两个仿射对应来估计两个半标定相机之间的公共焦距和基本矩阵的最小解法。其利用局部仿射变换导出的线性约束扩展了点对应技术，并通过隐变量技术高效地求解多元多项式系统。同时，为了选择出最优解，引入了新颖的条件和根选择技术，在高噪声情况下表现优异。该算法在合成数据和104对公开的实际图像上得到验证，论文中还包括了MATLAB实现。

使用两个仿射对应进行两视图焦距估计的最小解决方案