Estimation and Post-Capture Compensation of Synchronization Error in Unsynchronized Multi-Camera Systems

• Multi-camera systems are used in entertainment production, computer vision, industry and surveillance. The benefit of using multi-camera systems is the ability to recover the 3D structure, or depth, of the recorded scene. However, various types of cameras, including depth cameras, can not be reliably synchronized during recording, which leads to errors in depth estimation and scene rendering. The aim of this work is to propose a method for compensating synchronization errors in already recorded sequences, without changing the format of the recorded sequences. We describe a depth uncertainty model for parametrizing the impact of synchronization errors in a multi-camera system, and propose a method for synchronization error estimation and compensation. The proposed method is based on interpolating an image at a desired timeframe based on adjacent non-synchronized images in a single camera's sequence, using an array of per-pixel distortion vectors. This array is generated by using the difference between adjacent images to locate and segment the recorded moving objects, and does not require any object texture or distinguishing features beyond the observed difference in adjacent images. The proposed compensation method is compared with optical-flow based interpolation and sparse correspondence based morphing, and the proposed synchronization error estimation is compared with a state-of-the-art video alignment method. The proposed method shows better synchronization error estimation accuracy and compensation ability, especially in cases of low-texture, low-feature images. The effect of using data with synchronization errors is also demonstrated, as is the improvement gained by using compensated data. The compensation of synchronization errors is useful in scenarios where the recorded data is expected to be used by other processes that expect a sub-frame synchronization accuracy, such as depth-image-based rendering.

Ämnesord

NATURVETENSKAP  -- Data- och informationsvetenskap (hsv//swe)

NATURAL SCIENCES  -- Computer and Information Sciences (hsv//eng)

Nyckelord

Multi-camera systems

Synchronization

Multiview

3D Acquisition

Video alignment

Depth uncertainty

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