Spatial Filtering Requirements for Gradient-Based Optical Flow Measurement
نویسنده
چکیده
When using a gradient-based method to determine the optical flow field for an image sequence, it is generally appreciated that some spatial pre-filtering of the images is usually needed, particularly for large motion values. However the characteristics of the filter are not generally given. In this paper we analyse the motion measurement from the point of view of sampling theory. We show how an aliasing problem can arise due to undersampling in the temporal domain, and how this problem can be alleviated by appropriate post-sampling spatial filtering. We also demonstrate a connection between this filtering and the methods used to generate the spatial and temporal image intensity gradients.
منابع مشابه
Filtering requirements for gradient-based optical flow measurement
The accuracy of gradient-based optical flow algorithms depends on the ability to measure intensity gradients accurately. We show how the temporal gradient can be compromised by temporal aliasing arising from motion and how appropriate post-sampling spatial filtering improves the situation. We also demonstrate a benefit of using higher-order gradient estimators.
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