Improved Nearest Neighbor Distance Ratio for Matching Local Image Descriptors

We propose a novel local nearest neighbor distance (LNND) descriptor for anomaly detection in crowded scenes. Comparing with the commonly used low-level feature descriptors in previous works, LNND descriptor has two major advantages. First, LNND descriptor efficiently incorporates spatial and temporal contextual information around the video event that is important for detecting anomalous interaction among multiple events, while most existing feature descriptors only contain the information of single event. Second, LNND descriptor is a compact representation and its dimensionality is typically much lower than the low-level feature descriptor. Therefore, not only the computation time and storage requirement can be accordingly saved by using LNND descriptor for the anomaly detection method with offline training fashion, but also the negative aspects caused by using high-dimensional feature descriptor can be avoided. We validate the effectiveness of LNND descriptor by conducting extensive experiments on different benchmark datasets. Experimental results show the promising performance of LNND-based method against the state-of-the-art methods. It is worthwhile to notice that the LNND-based approach requires less intermediate processing steps without any subsequent processing such as smoothing but achieves comparable event better performance.

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Peer Review #1 of "Exotic lagomorph may influence eagle abundances and breeding spatial aggregations: a field study and meta-analysis on the nearest neighbor distance (v0.1)"

10.7287/peerj.4746v0.1/reviews/1 ◽

2018 ◽

Author(s):

R Figueroa

Keyword(s):

Field Study ◽

Peer Review ◽

Nearest Neighbor ◽

Meta Analysis ◽

Neighbor Distance ◽

Nearest Neighbor Distance

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The spatial pattern of a Juniperus communis var. depressa population on a continental dune in subarctic Québec, Canada

Canadian Journal of Forest Research ◽

10.1139/x99-018 ◽

1999 ◽

Vol 29 (4) ◽

pp. 446-450 ◽

Cited By ~ 7

Author(s):

Gilles Houle ◽

Mario Duchesne

Keyword(s):

Sex Ratio ◽

Nearest Neighbor ◽

Dispersion Pattern ◽

Neighbor Distance ◽

Juniperus Communis ◽

Biased Sex Ratio ◽

Males And Females ◽

Nearest Neighbor Distance ◽

Population Dispersion ◽

Crown Size

We performed a nearest-neighbor analysis to determine the population dispersion pattern and the association between males and females in a Juniperus communis L. var. depressa Pursh population occupying a continental dune in subarctic Quebec, Canada. The overall dispersion pattern was contagious, and males (or females) were proportionately as likely to have a male as they were to have a female nearest neighbor. Crown size was positively related to nearest-neighbor distance for the male-male comparison only, suggesting a somewhat stronger intrasex competition between males. Nearest-neighbor distance increased with crown size (significantly related to age) suggesting a change in the intensity of aggregation with age possibly related to self-thinning. Higher mortality as a result of stronger male-male competition could explain the female-biased sex ratio and the absence of spatial segregation between sexes. The overall contagious dispersion pattern in the population may be related to the fact that most seed cones fall directly underneath the mother plant. Birds can eat the cones of J. communis and thus disperse seeds. However, these seeds are deposited in clumps, a process that may also explain contagion within the population.

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