scholarly journals Automatic Three-Dimensional Measurement of Large-Scale Structure Based on Vision Metrology

2014 ◽  
Vol 2014 ◽  
pp. 1-10 ◽  
Author(s):  
Zhaokun Zhu ◽  
Banglei Guan ◽  
Xiaohu Zhang ◽  
Daokui Li ◽  
Qifeng Yu
Keyword(s):  
Large Scale ◽  
Three Dimensional ◽  
Large Scale Structure ◽  
Scale Structure ◽  
Blob Detection ◽  
Three Dimensional Measurement ◽  
Fully Automatic ◽  
Voting Strategy ◽  
Key Techniques

All relevant key techniques involved in photogrammetric vision metrology for fully automatic 3D measurement of large-scale structure are studied. A new kind of coded target consisting of circular retroreflective discs is designed, and corresponding detection and recognition algorithms based on blob detection and clustering are presented. Then a three-stage strategy starting with view clustering is proposed to achieve automatic network orientation. As for matching of noncoded targets, the concept of matching path is proposed, and matches for each noncoded target are found by determination of the optimal matching path, based on a novel voting strategy, among all possible ones. Experiments on a fixed keel of airship have been conducted to verify the effectiveness and measuring accuracy of the proposed methods.

scholarly journals Inferring high-redshift large-scale structure dynamics from the Lyman-α forest

2019 ◽  
Vol 630 ◽  
pp. A151 ◽  
Author(s):  
Natalia Porqueres ◽  
Jens Jasche ◽  
Guilhem Lavaux ◽  
Torsten Enßlin
Keyword(s):  
Large Scale ◽  
High Redshift ◽  
Three Dimensional ◽  
Large Scale Structure ◽  
Scale Structure ◽  
Modal Parameter ◽  
Large Scale Structures ◽  
Quasar Spectra ◽  
Large Scale Flow ◽  
Fully Bayesian

One of the major science goals over the coming decade is to test fundamental physics with probes of the cosmic large-scale structure out to high redshift. Here we present a fully Bayesian approach to infer the three-dimensional cosmic matter distribution and its dynamics at z >  2 from observations of the Lyman-α forest. We demonstrate that the method recovers the unbiased mass distribution and the correct matter power spectrum at all scales. Our method infers the three-dimensional density field from a set of one-dimensional spectra, interpolating the information between the lines of sight. We show that our algorithm provides unbiased mass profiles of clusters, becoming an alternative for estimating cluster masses complementary to weak lensing or X-ray observations. The algorithm employs a Hamiltonian Monte Carlo method to generate realizations of initial and evolved density fields and the three-dimensional large-scale flow, revealing the cosmic dynamics at high redshift. The method correctly handles multi-modal parameter distributions, which allow constraining the physics of the intergalactic medium with high accuracy. We performed several tests using realistic simulated quasar spectra to test and validate our method. Our results show that detailed and physically plausible inference of three-dimensional large-scale structures at high redshift has become feasible.

scholarly journals Clusters of Galaxies

1980 ◽  
Vol 5 ◽  
pp. 699-714 ◽  
Author(s):  
Neta A. Bahcall
Keyword(s):  
Large Scale ◽  
Large Scale Structure ◽  
Scale Structure ◽  
Clusters Of Galaxies ◽  
Groups Of Galaxies ◽  
Formation And Evolution ◽  
The Rich ◽  
The Many ◽  
The Universe

AbstractClusters and groups of galaxies contain the majority of galaxies in the universe. The rich clusters, while less numerous than the many poor groups, are the densest and largest systems known, and can be easily recognized and studied even at relatively large distances. Their study is important for understanding the formation and evolution of clusters and galaxies, and for a determination of the large-scale structure in the universe.

scholarly journals Erratum: Three-dimensional hydrodynamical simulations of the large-scale structure of W50-SS433

2008 ◽  
Vol 389 (2) ◽  
pp. 1008-1008 ◽  
Author(s):  
Jesús Zavala ◽  
Pablo F. Velázquez ◽  
Adriano H. Cerqueira ◽  
Gloria M. Dubner
Keyword(s):  
Large Scale ◽  
Three Dimensional ◽  
Large Scale Structure ◽  
Scale Structure ◽  
Hydrodynamical Simulations

Three-dimensional simulation of large-scale structure in the Universe

Nature ◽  
1983 ◽  
Vol 305 (5931) ◽  
pp. 196-198 ◽  
Author(s):  
Joan Centrella ◽  
Adrian L. Melott
Keyword(s):  
Large Scale ◽  
Three Dimensional ◽  
Large Scale Structure ◽  
Scale Structure ◽  
Dimensional Simulation ◽  
The Universe

scholarly journals Determination of the large-scale and super-large-scale structure by means of the space distribution of quasars

1986 ◽  
Vol 119 ◽  
pp. 495-496
Author(s):  
Y.Y. Zhou ◽  
D.P. Fang ◽  
Z.G. Deng ◽  
X.T. He
Keyword(s):  
Large Scale ◽  
Large Scale Structure ◽  
Scale Structure ◽  
Space Distribution ◽  
The Universe

It is very important to study the large-scale structure by means of the space distribution of quasars. Using this method, one may search for the more distant superclusters and explore the super-large-scale structure, i.e., the existence of super-superclusters. The answer to the problem would be of great interest. It is related to the question about the transition of the clustering of galaxies on about 100 Mpc to the uniformity of the universe. Recently Oort et al and de Ruiter et al suggested that the quasars are located in superclusters. So we soppose that analysing the space distribution of quasars might give us some information about the super-large-scale structure of the universe. But up to the present the study of the clustering of quasars has not obtained universally accepted conclusions; in fact, some of them, including grouping and clustering (Arp; Chu and Zhu), no clustering (Chu and Zhu; Osmer; Webster), clustering for z < 2 and no clustering for z > 2 (Fang et al) and stringing (Deng et al), are contradictory.

scholarly journals Radio Surveys and Large Scale Structure

1991 ◽  
Vol 44 (6) ◽  
pp. 759 ◽  
Author(s):  
PA Shaver
Keyword(s):  
Radio Source ◽  
Large Scale ◽  
Three Dimensional ◽  
Large Scale Structure ◽  
Radio Galaxies ◽  
Scale Structure ◽  
Radio Sources ◽  
Clusters Of Galaxies ◽  
Normal Galaxies ◽  
Dimensional Distribution

An analysis of the Molonglo Reference Catalogue indicates that significant departures from isotropy are present in the sky distribution of strong extragalactic radio sources. This has been shown to be due to local large scale structure, specifically a concentration to the supergalactic plane, which also influences the slope of the source counts. A study of the three-dimensional distribution of local radio galaxies shows that they are more strongly concentrated to the supergalactic plane than are optically�selected galaxies, and that the supergalactic concentration is more extensive than hitherto believed. It appears that radio galaxies (and clusters of galaxies) trace the 'skeleton' of large scale structure, about which normal galaxies are more loosely distributed. Thus, while large scale structure evidently complicates the interpretation of radio source counts, it appears that radiO surveys can be of value in exploring structures on the largest scales.

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