337 research outputs found
3D Reconstruction: Novel Method for Finding of Corresponding Points using Pseudo Colors
This paper deals with the reconstruction of spatial coordinates of an arbitrary point in a scene using two images scanned by a 3D camera or two displaced cameras. Calculations are based on the perspective geom-etry. Accurate determination of corresponding points is a fundamental step in this process. The usually used methods can have a problem with points, which lie in areas without sufficient contrast. This paper describes our proposed method based on the use of the relationship between the selected points and area feature points. The proposed method finds correspondence using a set of feature points found by SURF. An algorithm is proposed and described for quick removal of false correspondences, which could ruin the correct reconstruction. The new method, which makes use of pseudo color image representation (pseudo coloring) has been proposed subsequently. By means of this method it is possible to significantly increase the color contrast of the surveyed image, and therefore add more information to find the correct correspondence. Reliability of the found correspondence can be verified by reconstruction of 3D position of selected points. Executed experiments confirm our assumption
Cytogenetic Studies on Inherited Neurofibromatosis in Calves
International audienc
Testing QoE in Different 3D HDTV Technologies
The three dimensional (3D) display technology has started flooding the consumer television market. There is a number of different systems available with different marketing strategies and different advertised advantages. The main goal of the experiment described in this paper is to compare the systems in terms of achievable Quality of Experience (QoE) in different situations. The display systems considered are the liquid crystal display using polarized light and passive lightweight glasses for the separation of the left- and right-eye images, a plasma display with time multiplexed images and active shutter glasses and a projection system with time multiplexed images and active shutter glasses. As no standardized test methodology has been defined for testing of stereoscopic systems, we develop our own approach to testing different aspects of QoE on different systems without reference using semantic differential scales. We present an analysis of scores with respect to different phenomena under study and define which of the tested aspects can really express a difference in the performance of the considered display technologies
Equivalence of replica and cavity methods for computing spectra of sparse random matrices
We show by direct calculation that the replica and cavity methods are exactly
equivalent for the spectrum of Erdos-Renyi random graph. We introduce a
variational formulation based on the cavity method and use it to find
approximate solutions for the density of eigenvalues. We also use this
variational method for calculating spectra of sparse covariance matrices
Loop expansion around the Bethe-Peierls approximation for lattice models
We develop an effective field theory for lattice models, in which the only
non-vanishing diagrams exactly reproduce the topology of the lattice. The
Bethe-Peierls approximation appears naturally as the saddle point
approximation. The corrections to the saddle-point result can be obtained
systematically. We calculate the lowest loop corrections for magnetisation and
correlation function.Comment: 8 page
Statistical properties of stock order books: empirical results and models
We investigate several statistical properties of the order book of three
liquid stocks of the Paris Bourse. The results are to a large degree
independent of the stock studied. The most interesting features concern (i) the
statistics of incoming limit order prices, which follows a power-law around the
current price with a diverging mean; and (ii) the humped shape of the average
order book, which can be quantitatively reproduced using a `zero intelligence'
numerical model, and qualitatively predicted using a simple approximation.Comment: Revised version, 10 pages, 4 .eps figures. to appear in Quantitative
Financ
Dynamic scaling and universality in evolution of fluctuating random networks
We found that models of evolving random networks exhibit dynamic scaling
similar to scaling of growing surfaces. It is demonstrated by numerical
simulations of two variants of the model in which nodes are added as well as
removed [Phys. Rev. Lett. 83, 5587 (1999)]. The averaged size and connectivity
of the network increase as power-laws in early times but later saturate.
Saturated values and times of saturation change with paramaters controlling the
local evolution of the network topology. Both saturated values and times of
saturation obey also power-law dependences on controlling parameters. Scaling
exponents are calculated and universal features are discussed.Comment: 7 pages, 6 figures, Europhysics Letters for
Opinion dynamics in a three-choice system
We generalize Galam's model of opinion spreading by introducing three
competing choices. At each update, the population is randomly divided in groups
of three agents, whose members adopt the opinion of the local majority. In the
case of a tie, the local group adopts opinion A, B or C with probabilities
alpha, beta and (1-alpha-beta) respectively. We derive the associated phase
diagrams and dynamics by both analytical means and simulations. Polarization is
always reached within very short time scales. We point out situations in which
an initially very small minority opinion can invade the whole system.Comment: To appear in European Physical Journal B. A few errors corrected,
some figures redrawn from the first versio
Size-resolved aerosol water-soluble ionic compositions in the summer of Beijing: implication of regional secondary formation
To characterize aerosol pollution in Beijing, size-resolved aerosols were collected by MOUDIs during CAREBEIJING-2006 field campaign at Peking University (urban site) and Yufa (upwind rural site). Fine particle concentrations (PM<sub>1.8</sub> by MOUDI) were 99.8&plusmn;77.4 &mu;g/m<sup>3</sup> and 78.2&plusmn;58.4 &mu;g/m<sup>3</sup>, with PM<sub>1.8</sub>/PM<sub>10</sub> ratios of 0.64&plusmn;0.08 and 0.76&plusmn;0.08 at PKU and Yufa, respectively, and secondary compounds accounted for more than 50% in fine particles. PMF model analysis was used to resolve the particle modes. Three modes were resolved at Yufa, representing condensation, droplet and coarse mode. However, one more droplet mode with bigger size was resolved, which was considered probably from regional transport. Condensation mode accounted for 10%–60% of the total mass at both sites, indicating that the gas-to-particle condensation process was important in summer. The formation of sulfate was mainly attributed to in-cloud or aerosol droplet process (PKU 80%, Yufa 70%) and gas condensation process (PKU 14%, Yufa 22%). According to the thermodynamic instability of NH<sub>4</sub>NO<sub>3</sub>, size distributions of nitrate were classified as three categories by RH. The existence of Ca(NO<sub>3</sub>)<sub>2</sub> in droplet mode indicated the reaction of HNO<sub>3</sub> with crustal particles was also important in fine particles. A rough estimation was given that 69% of the PM<sub>10</sub> and 87% of the PM<sub>1.8</sub> in Beijing urban were regional contributions. Sulfate, ammonium and oxalate were formed regionally, with the regional contributions of 90%, 87% and 95% to PM<sub>1.8</sub>. Nitrate formation was local dominant. In summary regional secondary formation led to aerosol pollution in the summer of Beijing
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