engleski

Histogram-Based Description of Local Space-Time Appearance

We introduce a novel local spatio-temporal descriptor intended to model the spatio-temporal behavior of a tracked object of interest in a general manner. The basic idea of the descriptor is the accumulation of histograms of an image function value through time. The histograms are calculated over a regular grid of patches inside the bounding box of the object and normalized to represent empirical prob- ability distributions. The number of grid patches is fixed, so the descriptor is invariant to changes in spatial scale. Depending on the temporal complexity/details at hand, we introduce "first order STA descriptors" that describe the average distribution of a chosen image function over time, and "second order STA descriptors" that model the distribution of each histogram bin over time. We discuss entropy and 2 as well-suited similarity and saliency measures for our descriptors. Our experimental validation ranges from the patch- to the object-level. Our results show that STA, this simple, yet powerful novel description of local space-time appearance is well-suited to machine learning and will be useful in video- analysis, including potential applications of object detection, tracking, and background modeling.

computer vision; motion analysis; histogram based description

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