34245222
Parametric tracking of human contour by exploiting intelligent edge
We adapt the idea of intelligent scissors for contour tracking in dynamic image sequence. Tracking contour of human can therefore be converted to tracking seed points in images by making use of the properties of the optimal path (intelligent edge). The main advantage of the approach is that it can handle correctly occlusions that occur frequently when human is moving. Non-uniform rational B-spline (NURBS) is used to represent parametrically the contour that we want to track. In order to track robustly the contour in images, similarity and compatibility measurements of the edge are computed as the weighting functions of optimal estimator. To reduce dramatically the computational load, an efficient method for extracting the region that we are interested in is proposed. Experiments show that our approach works robustly with sequences with frequent occlusions.
16243325
Parametric reconstruction of generalized cylinders from limb edges
The three-dimensional (3-D) reconstruction of generalized cylinders (GCs) is an important research field in computer vision. One of the main difficulties is that some contour features in images cannot be reconstructed by traditional stereovision because they do not correspond to reflectance discontinuities of surface in space. In this paper, we present a novel, parametric approach for the 3-D reconstruction of circular generalized cylinders (CGCs) only from the limb edges of CGCs in two images. Instead of exploiting the invariant and quasiinvariant properties of some specific subclasses of GCs in projections, our reconstruction is achieved by some general assumptions on GCs, and can, therefore, be applied to a broader subclass of GCs. In order to improve robustness, we perform the extraction and labeling of the limb edge interactively, and estimate the epipolar geometry between two images by an optimal algorithm. Then, for different types of GCs, three kinds of symmetries (parallel symmetry, skew symmetry, and local smooth symmetry) are employed to compute the symmetry of limb edges. The surface points corresponding to limb edges in images are reconstructed by integrating the recovered epipolar geometry and the properties induced from the assumptions that we make on the GCs. Finally, a homography-based method is exploited to further refine the 3-D description of the GC with a coplanar curved axis.
15257131
Incremental Maintenance of Discovered Mobile User Maximal Moving Sequential Patterns
In the context of mobile computing, a special sequential pattern, moving sequential pattern that reflects the moving behavior of mobile users attracted researchers' interests recently. While there have been a number of efficient moving sequential pattern mining algorithms reported, this paper concentrates on the maintenance of mined maximal moving sequential patterns. In particular, we developed an incremental approach, where maximal moving sequential patterns are stored in prefix trees, and new moving sequences can be easily combined with the existing patterns. A performance study indicated that the proposed approach performs significantly faster than straightforward approaches that mine from the whole updated database.
15769711
Combining Clustering with Moving Sequential Pattern Mining: A Novel and Efficient Technique
Sequential pattern mining is a well-studied problem. In the context of mobile computing, moving sequential patterns that reflects the moving behavior of mobile users attracted researchers’ interests recently. In this paper a novel and efficient technique is proposed to mine moving sequential patterns. Firstly the idea of clustering is introduced to process the original moving histories into moving sequences as a preprocessing step. Then an efficient algorithm called PrefixTree is presented to mine the moving sequences. Performance study shows that PrefixTree outperforms LM algorithm, which is revised to mine moving sequences, in mining large moving sequence databases.
32200257
Partial difference sets
A (?,k,?,β)-partial difference set in a finite group G of order ? is a subset D of G with k distinct elements such that expressions dnd?12 for d1 and d2 in D, represent each non-identity element not contained in D exactly ? times and each non-identity element contained in D exactly ?+β times. Such a set is closely related to association schemes of PBIB designs with two associate classes.
6066243
Extending Dependencies with Conditions
This paper introduces a class of conditional inclusion dependencies (CINDs), which extends traditional inclusion dependencies (INDs) by enforcing bindings of semantically related data values. We show that CINDs are useful not only in data cleaning, but are also in contextual schema matching [7]. To make effective use of CINDs in practice, it is often necessary to reason about them. The most important static analysis issue concerns consistency, to determine whether or not a given set of CINDs has conflicts. Another issue concerns implication, i.e., deciding whether a set of CINDs entails another CIND. We give a full treatment of the static analyses of CINDs, and show that CINDs retain most nice properties of traditional INDs: (a) CINDs are always consistent; (b) CINDs are finitely axiomatizable, i.e., there exists a sound and complete inference system for implication of CINDs; and (c) the implication problem for CINDs has the same complexity as its traditional counterpart, namely, PSPACE-complete, in the absence of attributes with a finite domain; but it is EXPTIME-complete in the general setting. In addition, we investigate the interaction between CINDs and conditional functional dependencies (CFDs), an extension of functional dependencies proposed in [9]. We show that the consistency problem for the combination of CINDs and CFDs becomes undecidable. In light of the undecidability, we provide heuristic algorithms for the consistency analysis of CFDs and CINDs, and experimentally verify the effectiveness and efficiency of our algorithms.
42785568
Abelian Difference Sets Without Self-conjugacy
We obtain some results that are useful to the study of abelian difference sets and relative difference sets in cases where the self-conjugacy assumption does not hold. As applications we investigate McFarland difference sets, which have parameters of the form v=qd+1( qd+ qd-1 +...+ q+2) ,k=qd( qd+qd-1+...+q+1) , λ = qd ( q(d-1)+q(d-2)+...+q+1), where q is a prime power andd a positive integer. Using our results, we characterize those abelian groups that admit a McFarland difference set of order k-λ = 81. We show that the Sylow 3-subgroup of the underlying abelian group must be elementary abelian. Our results fill two missing entries in Kopilovich's table with answer “no”.