WSCG '2012: Poster Paper Proceedings
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Item Robust Affinity Propagation using Preference Estimation(Václav Skala - UNION Agency, 2012) Yang, Kai-Chao; Yu, Chang-Hsin; Wang, Jia-Shung; Skala, VáclavAffinity propagation is a novel unsupervised learning algorithm for exemplar-based clustering without the priori knowledge of the number of clusters (NC). In this article, the influence of the “preference” on the accuracy of AP output is addressed. We present a robust AP clustering method, which estimates what preference value could possibly yield an optimal clustering result. To demonstrate the performance promotion, we apply the robust AP on picture clustering, using local SIFT, global MPEG-7 CLD, and the proposed preference as the input of AP. The experimental results show that over 40% enhancement of ARI accuracy for several image datasets.
Item Self-speed and headway measurement in highway traffic from onboard video footage(Václav Skala - UNION Agency, 2012) Vergeest, Joris S. M.; Skala, VáclavWe present a method to automatically collect data about distance and speed of vehicles ahead of a car participating in highway traffic. The method should support the registration of traffic in front of a driving car over long periods of time in order to be able to detect over-persistent congestion (OPC) situations. The method requires no specialized devices; it is based on a simple video stream from any (low-cost) camera mounted near the front window of a car. The data is used to fine-tune traffic flow models in order to determine the conditions for the emergence and the dissipation of traffic jams more accurately. The paper deals with the performance of the vehicle tracking method itself and presents a criterion for over-persistent traffic jams applied to the data. The outlook towards a driver’s advisory system to reduce traffic congestion (and thus time loss and environmental load) is discussed as well.Item Use the palmprint for identification and authentication of persons: a new real-time method of data treatment based on graph construction of spatial interest points(Václav Skala - UNION Agency, 2012) Simac-Lejeune, Alain; Skala, VáclavThe identification and authentication of individuals by their palmprints is a recent approach in the family of biometric modalities, very interesting in appearance and non-contact non-intrusive. It was recently studied in topic research over the last decade. The proposed approaches are mostly based on methods of classification and learning. However, the complexity of the calculations leads to an inappropriate application in real time. In our work, we investigated the use of basic primitives pictures more precisely the Space Interest Points (SIO) in a realtime process of identification and authentication of palmprint. This process is based on construction and matching of graph. By setting few constraints and working with matching methods and matching specific, experimental results suggest a robust real-time solution as good as the best methods with an error rate authentication below 1% for a population of 20 individuals.Item Visual acuity and comfortable distance from a Display(Václav Skala - UNION Agency, 2012) Seeman, Michal; Zemčík, Pavel; Skala, VáclavThe image perception in humans depends on many factors. One of the most important ones is certainly the observing distance. The distance from which human look at the images is important for studying image perception in general and in particular on display devices. This paper describes a method of measurement of the preferred observing distance among humans of different age, sex, etc. under controlled conditions.Item Geodesic stripes based hierarchical evaluation for 3D facial similarity(Václav Skala - UNION Agency, 2012) Li, Hongyan; Wu, Zhongke; Donghua, Huang; Skala, VáclavSimilarity evaluation of 3D face is the core issue in 3D face recognition. The article puts forwards a geodesic stripes based evaluation method which realizes assessment from global face to local parts. It can be used to make effective and comprehensive evaluation in many fields such as 3D face reconstruction, forensic science, archaeology etc. First, simplify each 3D face with a series of geodesic stripes and calculate distribution vector between each pair of stripes, which reflects 3D space distribution feature. Then through feature extraction on entire face, we get a distribution matrix which consists of all distribution vectors. The similarity between two distribution matrices directly shows the global similarity between two faces. We also extract geodesic stripes feature on local organs like mouth eye and nose to make a more accurate evaluation. The experimental results on SHREC2008 3D face database further testify that the hierarchical evaluation method is available and consistent with the subjective evaluation.Item Virtual reality system as a tool for education(Václav Skala - UNION Agency, 2012) Kovalčík, V.; Chmelík, J.; Bezděka, M.; Sochor, J.; Skala, VáclavEducation in the field of computer graphics is attractive, but the necessity of strong theoretical background and the amount of work needed before achieving a non-trivial output could be discouraging for many students. To cope with inherent complexity of computer graphics applications, we designed a system intended to reduce implementation burden and help the students to achieve interesting results in less time. In our labs we use an in-house virtual reality system, which has been gradually improved by the work of our students and staff for a period of more than eight years. The foundation of the system is a modular architecture that allows rapid assembly of prototyped applications as well as easy implementation of extensions. Computer graphics students with even a fundamental level of knowledge are encouraged to participate in the lab projects. Working on system that allows rapid prototyping and shortens the path to achieving interesting visible results, builds up the students’ motivation and it is a key element of a continuous improvement during the study.Item Implementing interactive 3D segmentation on CUDA using graph-cuts and watershed transformation(Václav Skala - UNION Agency, 2012) Kolomazník, Jan; Horáček, Jan; Krajíček, Václav; Pelikán, Josef; Skala, VáclavIn this paper we present a novel scheme for a very fast implementation of volumetric segmentation using graph cuts. The main benefit of this work is our approach to non-grid region adjacency processing on CUDA which to our knowledge has not been done yet in any efficient way. The watershed transform radically reduces the number of vertices for graph processing. Everything starting from watershed transformation and ending with graph cut was parallelized and is performed directly on the GPU.Item 3D as a method of geometrical simulation (on the example of combination of a quadric and conic)(Václav Skala - UNION Agency, 2012) Kheyfets, Alexander L.; Skala, VáclavIt is shown that on the example of the mentioned problem 3d-computer geometrical models allow in full to solve and investigate applied problems of geometrical simulation.Item Convex envelope generation using a mix of gift wrap and quickhull algorithms(Václav Skala - UNION Agency, 2012) Fares, Charbel; Skala, VáclavThe environment simulation is widely used nowadays. Training in many fields such as medicine and architecture heavily depends on virtual reality techniques. Since objects in real life do not have a deterministic shape it is not possible to have a geometric equation that might model them. Convex Hulls (or Convex Envelopes) are a must in such simulations. The need for convex envelopes rises with the intention of having realistic scenes with exact collision detection between objects in the virtual world. In this paper, four algorithms for generating the convex hull are discussed, implemented and compared. The first three algorithms are the Brute Force, the Gift Wrap and the QuickHull algorithm. The fourth one is a hybrid approach that combines the QuickHull and the Gift Wrap algorithms. Simulations were done in the medical environment, and algorithms are tested with the model of 3D wrist and knee bones.Item Geometric modeling of pelvic organs with a discrete offset approach(Václav Skala - UNION Agency, 2012) Bay, Thierry; Raffin, Romain; Daniel, Marc; Skala, VáclavIn order to design a patient-specific simulator of pelvic organs, MoDyPe project considers the organs as thick surfaces. Starting from a closed parametric surface for the outer hull, an offset approach is applied. However, respecting the thickness on the surface and ensuring the absence of self-intersection is impossible if the shape has too important local curvatures. Two iterative approaches are compared. The first method is based on a B-spline formulation, and the second one on a mass-spring system (MSS). Our second method on discrete representation permits to obtain more accurate results with a more flexible formulation of the problem.Item Map point-labeling with rotation in slider model(Václav Skala - UNION Agency, 2012) Asoodeh, Amir Safar; Rostamabadi, Farshad; Ahmadi, Ali; Skala, VáclavGiven n point coordinates and their various labels’ length, our algorithm places a rotated collision-free label for each point. Using a combination of genetic algorithms and simulated annealing as an evolutionary algorithm, with qualification function consuming just 0(nlogn) time, we achieve a fast near-optimal algorithm.
