Time-recursive velocity-adapted spatio-temporal scale-space filters

Tony Lindeberg

Technical report CVAP258, ISRN KTH NA/P--01/23--SE. Department of Numerical Analysis and Computer Science, KTH (Royal Institute of Technology), S-100 44 Stockholm, Sweden.

Shortened version in Proc. ECCV'02, Copenhagen, Denmark, May 2002. Springer Lecture Notes in Computer Science, vol 2350, pages I:52--67.

Abstract

This paper presents a framework for constructing and computing velocity-adapted scale-space filters for spatio-temporal image data. Starting from basic criteria in terms of time-causality, time-recursivity, locality and adaptivity with respect to motion estimates, a family of spatio-temporal recursive filters is proposed and analysed. An important property of the proposed family of smoothing kernels is that the spatio-temporal covariance matrices of the discrete kernels obey similar transformation properties under Galilean transformations as for continuous smoothing kernels on continuous domains. Moreover, the proposed framework provides an efficient way to compute and generate non-separable scale-space representations without need for explicit external warping mechanisms or keeping extended temporal buffers of the past. The approach can thus be seen as a natural extension of recursive scale-space filters from pure temporal data to spatio-temporal domains.

Receptive field profiles generated by the proposed theory show high qualitative similarities to receptive field profiles recorded from biological vision.

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Related publications: (Application of velocity adapted filtering to recognition of activities) (Linear spatio-temporal scale-space) (Separable scale-space with causal time direction) (Automatic selection of temporal scales in time-causal scale-space) (Discrete scale-space theory on a spatial domain based on non-creation of local extrema) (Discrete scale-space theory on a spatial domain based on non-enhancement of local extrema) (Monograph on scale-space theory)