Corners are popular features for relative pose computation with 2D-2D point correspondences. Stable corners may be formed by two 3D rays sharing a common starting point. We call such elements ray-point-ray (RPR) structures. Besides a local invariant keypoint given by the lines’ intersection, their reprojection also defines a corner orientation and an inscribed angle in the image plane. The present paper investigates such RPR features, and aims at answering the fundamental question of what additional constraints can be formed from correspondences between RPR features in two views. In particular, we show that knowing the value of the inscribed angle between the two 3D rays poses additional constraints on the relative orientation. Using the latter enables the solution of the relative pose problem with as few as 3 correspondences across the two images. We provide a detailed analysis of all minimal cases distinguishing between 90-degree RPR-structures and structures with an arbitrary, known inscribed angle. We furthermore investigate the special cases of a known directional correspondence and planar motion, the latter being solvable with only a single RPR correspondence. We complete the exposition by outlining an image processing technique for robust RPR-feature extraction. Our results suggest high practicality in man-made environments, where 90-degree RPR-structures naturally occur.

中文翻译：

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使用射线点射线特征的最小案例相对姿势计算

角点是用于2D-2D点对应关系的相对姿势计算的常用功能。稳定的角可以由共享同一起点的两条3D射线形成。我们称此类元素为射线点射线（RPR）结构。除了由线的交点指定的局部不变关键点外，它们的重投影还定义了图像平面中的角方向和内切角。本文研究了此类RPR功能，旨在回答以下基本问题：可以从两种视图中的RPR功能之间的对应关系形成哪些附加约束。尤其是，我们表明，知道两条3D射线之间的内接角的值会对相对方向造成其他限制。使用后者可以解决相对姿势问题，在两个图像上只有3个对应关系。我们对所有最小情况进行详细分析，以区分90度RPR结构和具有任意已知内接角的结构。我们进一步研究了已知的方向对应和平面运动的特殊情况，后者仅通过单个RPR对应就可以解决。我们通过概述用于鲁棒RPR特征提取的图像处理技术来完成本次博览会。我们的结果表明，在人造环境中具有很高的实用性，在人造环境中自然会出现90度RPR结构。后者仅需一个RPR即可解决。我们通过概述用于鲁棒RPR特征提取的图像处理技术来完成本次博览会。我们的结果表明，在人造环境中具有很高的实用性，在人造环境中自然会出现90度RPR结构。后者仅需一个RPR即可解决。我们通过概述用于鲁棒RPR特征提取的图像处理技术来完成本次博览会。我们的结果表明，在人造环境中具有很高的实用性，在人造环境中自然会出现90度RPR结构。