The approximability of several NP maximization problems is investigated and strong lower bounds for the studied problems are proved. For some of the problems the bounds are the best that can be achieved, unless P = NP...
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This article presents: (i) a multiscale representation of grey-level shape called the scale-space primal sketch, which makes explicit both features in scale-space and the relations between structures at different scal...
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This article presents: (i) a multiscale representation of grey-level shape called the scale-space primal sketch, which makes explicit both features in scale-space and the relations between structures at different scales, (ii) a methodology for extracting significant blob-like image structures from this representation, and (iii) applications to edge detection, histogram analysis, and junction classification demonstrating how the proposed method can be used for guiding later-stage visual processes. The representation gives a qualitative description of image structure, which allows for detection of stable scales and associated regions of interest in a solely bottom-up data-driven way. In other words, it generates coarse segmentation cues, and can hence be seen as preceding further processing, which can then be properly tuned. It is argued that once such information is available, many other processing tasks can become much simpler. Experiments on real imagery demonstrate that the proposed theory gives intuitive results.
MIN PB is the class of minimization problems whose objective functions are bounded by a polynomial in the size of the input. We show that there exist several problems which are MIN PB-complete with respect to an appro...
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An intertwine of two graphs H and H′ is a graph G such that G contains both H and H′ as minors, but no proper minor of G contains both H and H′ as minors. We give an upper bound on the size of an intertwine of two ...
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We present a computational model for attention. It consists of an early parallel stage with preattentive cues followed by a later serial stage, where the cues are integrated. We base the model on disparity image flow ...
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作者：
Nordlund, PeterEklundh, Jan-Olof
Department of Numerical Analysis and Computing Science Royal Institute of Technology StockholmS-100 44 Sweden
An approach to figure-ground segmentation based on a 2-dimensional histogram in feature space is presented. The histogram is then analyzed with a peak-finding algorithm designed with real-time performance in mind. The...
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We investigate numerically a mathematical model of a consolidation process of a dense, flocculated suspension. The suspension is treated as a two-constituent mixture of a fluid and solid particles by an Eulerian two-p...
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We investigate numerically a mathematical model of a consolidation process of a dense, flocculated suspension. The suspension is treated as a two-constituent mixture of a fluid and solid particles by an Eulerian two-phase fluid model. We characterize the suspension by constitutive relations concerning the stresses, interaction forces and interparticle forces. A numerical solver for a two dimensional test case is developed using finite difference methods both in time and space. In the numerical experiments, the suspension is confined to a closed box and consolidates due to a constant gravity field directed toward the bottom. To study the effect of shear, 2D simulations are performed where the bottom wall of the box is moving with a constant speed.
NLCk is a family of algebras on vertex-labeled graphs introduced by Wanke. An NLC-decomposition of a graph is a derivation of this graph from single vertices using the operations in question. The width of the decompos...
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作者：
Fornland, Päir
Department of Numerical Analysis and Computing Science Royal Institute of Technology StockholmS-100 44 Sweden
Autonomous vehicles need a means of detecting obstructions on its path, to avoid collision. In this paper, a novel approach to obstacle detection is presented. A camera moves on a visible ground plane with the optical...
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The Matrix-To-Line problem is that of, given an n × n symmetric matrix D, finding an arrangement of n points on the real line such that the so obtained distances agree as well as possible with the by D specified ...
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