Title
Joint segmentation of collectively moving objects using a bag-of-words model and level set evolution
Abstract
In scenes with collectively moving objects, to disregard the individual objects and take the entire group into consideration for motion characterization is a promising approach with wide application prospects. In contrast to studies on the segmentation of independently moving objects, our purpose is to construct a segmentation of these objects to characterize their motions at a macroscopic level. In general, the collectively moving objects in a group have very similar motion behavior with their neighbors and appear as a kind of global collective motion. This paper presents a joint segmentation approach for these collectively moving objects. In our model, we extract these macroscopic movement patterns based on optical flow field sequences. Specifically, a group of collectively moving objects correspond to a region where the optical flow field has high magnitude and high local direction coherence. As a result, our problem can be addressed by identifying these coherent optical flow field regions. The segmentation is performed through the minimization of a variational energy functional derived from the Bayes classification rule. Specifically, we use a bag-of-words model to generate a codebook as a collection of prototypical optical flow patterns, and the class-conditional probability density functions for different regions are determined based on these patterns. Finally, the minimization of our proposed energy functional results in the gradient descent evolution of segmentation boundaries which are implicitly represented through level sets. The application of our proposed approach is to segment and track multiple groups of collectively moving objects in a large variety of real-world scenes.
Year
DOI
Venue
2012
10.1016/j.patcog.2012.03.010
Pattern Recognition
Keywords
Field
DocType
global collective motion,optical flow field,motion characterization,entire group,coherent optical flow field,prototypical optical flow pattern,optical flow field sequence,joint segmentation approach,level set evolution,bag-of-words model,multiple group,segmentation boundary,segmentation,bag of words,level set
Bag-of-words model,Computer vision,Gradient descent,Scale-space segmentation,Pattern recognition,Segmentation,Level set,Coherence (physics),Artificial intelligence,Energy functional,Optical flow,Mathematics
Journal
Volume
Issue
ISSN
45
9
0031-3203
Citations 
PageRank 
References 
4
0.42
36
Authors
2
Name
Order
Citations
PageRank
Si Wu114816.73
Hau-San Wong2100886.89