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Over the last few decades, the methods of global image orientation, which is also called global SfM, have attracted a lot of attention from researchers, mainly thanks to its advantage of time efficiency. Based on the input of relative orientation results, most conventional global SfM methods employ a two-step strategy consisting of global rotation estimation and global translation estimation. This paper, on the contrary, introduces a hybrid global approach that intends to solve global rotations and translations synchronously, but hierarchically. To improve the robustness and time efficiency, we first propose a novel efficient method that is much faster than the previous approaches for extracting an optimal minimum cover of a connected image triplet set (OMCTS). The OMCTS makes all the available images contained in a minimum number of connected image triplets, as well as all of those selected triplets, satisfy the constraint that the three corresponding relative orientations are as compatible as possible to each other. In order to solve non-collinear triplets in the OMCTS, some fundamental characterizations of essential matrices in the multiple-image setting are used, and image pose parameters are then estimated via averaging the constrained essential matrices. For the collinear triplets, the above approach is invalid and the image pose parameters are then alternatively determined from the relative orientations using the depth of tie points from each individual local spatial intersection. Finally, all image orientations are moved to a common coordinate system by traversing the solved connected triplets using similarity transformations. Compared to the state-of-the-art global SfM methods, the performance and capability of the proposed hybrid approach are thoroughly demonstrated on various public datasets (mainly including ordered and unordered internet images, oblique aerial images, hard and complex datasets, etc.). [ABSTRACT FROM AUTHOR]