Abstract. We study the inverse problem of estimating n locations t 1 , t 2 , . . . , tn (up to global scale, translation and negation) in R d from noisy measurements of a subset of the (unsigned) pairwise lines that connect them, that is, from noisy measurements of ± t i −t j t i −t j 2 for some pairs (i, j) (where the signs are unknown). This problem is at the core of the structure from motion (SfM) problem in computer vision, where the t i 's represent camera locations in R 3 . The noiseless version of the problem, with exact line measurements, has been considered previously under the general title of parallel rigidity theory, mainly in order to characterize the conditions for unique realization of locations. For noisy pairwise line measurements, current methods tend to produce spurious solutions that are clustered around a few locations. This sensitivity of the location estimates is a well-known problem in SfM, especially for large, irregular collections of images.In this paper we introduce a semidefinite programming (SDP) formulation, specially tailored to overcome the clustering phenomenon. We further identify the implications of parallel rigidity theory for the location estimation problem to be well-posed, and prove exact (in the noiseless case) and stable location recovery results. We also formulate an alternating direction method to solve the resulting semidefinite program, and provide a distributed version of our formulation for large numbers of locations. Specifically for the camera location estimation problem, we formulate a pairwise line estimation method based on robust camera orientation and subspace estimation. Lastly, we demonstrate the utility of our algorithm through experiments on real images.Key words. Structure from motion, parallel rigidity, semidefinite programming, convex relaxation, alternating direction method of multipliers AMS subject classifications. 68T45, 52C25, 90C22, 90C251. Introduction. Global positioning of n objects from partial information about their relative locations is prevalent in many applications spanning fields such as sensor network localization [8,58,16,18], structural biology [31], and computer vision [27,9]. A well-known instance that attracted much attention from both the theoretical and algorithmic perspectives is that of estimating the locations t 1 , t 2 , . . . , t n ∈ R d from their pairwise Euclidean distances t i − t j 2 . In this case, the large body of literature in rigidity theory (cf. [4, 54]) provides conditions under which the localization is unique given a set of noiseless distance measurements. Also, much progress has been made with algorithms that estimate positions from noisy distances, starting with classical multidimensional scaling [48] to the more recent semidefinite programming (SDP) approaches (see, e.g., [8,7]).Here we consider a different global positioning problem, in which the locations t 1 , . . . , t n need to be estimated from a subset of (potentially noisy) measurements of the pairwise lines that connect them (see Figure 1.1 for a ...