Through-the-Lens Synchronisation for Heterogeneous Camera Networks
Evren İmre, Adrian Hilton · 2012
Camera synchronisation involves the temporal alignment of a set of video sequences, independently acquired by two or more cameras. Accurate synchronisation is crucial for a wide variety of applications requiring multi-camera setups, ranging from 3D modelling of dynamic scenes (e.g., featuring a performance, or a sports event) to video surveillance and superresolution. Conventional synchronisation methods, which typically rely on hardware or audio signals, have practical limitations, imposing constraints on the size and the span of the network [2][1]. Through-the-lens synchronisation offers a robust and flexible way to synchronise a camera network from the content it generates. In this paper, we propose a bottom-up synchronisation algorithm to estimate a frame rate and an offset for each member of a network composed of 2 or more cameras. Our approach involves the computation of a relative synchronisation estimate between each camera pair, from which the absolute synchronisation parameters of the individual cameras are calculated (Figure 1). The algorithm can handle hybrid networks of static and moving cameras with different resolutions and frame rates, and does not require rigid objects, long trajectories or overlapping fields-of-view beyond 2 cameras. It needs a set of image features on the dynamic scene elements, and the geometric relation between the images (which can be obtained from the static background features). Relative Synchronisation: The frame indices of the jth camera (t j) with respect to those of ith (ti) is defined by the line