scholarly journals Geometric Calibration of Rotational Vision System for Dynamic Exterior Orientation

2021 ◽  
Author(s):  
Mouze Qiu ◽  
Jin Zhang ◽  
Xiaonan Xiong ◽  
Kai Zheng ◽  
Ze Yang ◽  
...  
Keyword(s):  
Rotation Axis ◽  
Vision System ◽  
Active Vision ◽  
Rotating Platform ◽  
Exterior Orientation ◽  
Geometric Calibration ◽  
Estimation Algorithms ◽  
Rotation Axes ◽  
Rotation Motion ◽  
Rotational Freedom

Abstract Rotational vision system (RVS) is a common type of active vision with only rotational freedom. Typically, the rotational freedom is provided by turntable and pan-tilt-zoom (PTZ). Or eye in hand (EIH) structure in an articulated arm robot. The ideal assumption that rotation axes are perfectly aligned with the coordinate axes of the local camera is mostly violated due to assembling deviations and limitations of manufacturing accuracy. To solve this problem, we propose a generalized deviation model for a specified rotation axis that relates the rotation motion of the platform to the exterior orientation (EO) of the camera. Based on it we put heuristic estimation algorithms through minimizing global reprojection error and fitting a circle in space respectively for rotating platform with or without accurate angle measurements with constrained global optimization. Implemented experiments on a servo pan-tilt turntable validate the accuracy and efficiency of the above models and calibration technique.

Vibration Sensing of a Bridge Model Using a Multithread Active Vision System

2018 ◽  
Vol 23 (1) ◽  
pp. 179-189 ◽  
Author(s):  
Tadayoshi Aoyama ◽  
Makoto Chikaraishi ◽  
Akimasa Fujiwara ◽  
Liang Li ◽  
Mingjun Jiang ◽  
...  
Keyword(s):  
Vision System ◽  
Active Vision ◽  
Bridge Model ◽  
Vibration Sensing

BEHAVIOR-BASED ACTIVE VISION

1994 ◽  
Vol 08 (06) ◽  
pp. 1493-1526
Author(s):  
CLAUDIO S. PINHANEZ
Keyword(s):  
Vision System ◽  
Active Vision ◽  
Implementation Process ◽  
High Concentration ◽  
Subsumption Architecture ◽  
System A ◽  
Saccadic Movement ◽  
Building Process ◽  
Sensor Structure ◽  
Behavior Based

A vision system was built using a behavior-based model, the subsumption architecture. The so-called active eye moves the camera’s axis through the environment, detecting areas with high concentration of edges, with the help of a kind of saccadic movement. The design and implementation process is detailed in the article, paying particular attention to the fovea-like sensor structure which enables the active eye to efficiently use local information to control its movements. Numerical measures for the eye’s behavior were developed, and applied to evaluate the incremental building process and the effects of the saccadic movements on the whole system. A higher level behavior was also implemented, with the purpose of detecting long straight edges in the image, producing pictures similar to hand drawings. Robustness and efficiency problems are addressed at the end of the paper. The results seem to prove that interesting behaviors can be achieved using simple vision methods and algorithms, if their results are properly interconnected and timed.

On the factorization of rotations with examples in diffractometry

1990 ◽  
Vol 428 (1875) ◽  
pp. 451-472 ◽  
Keyword(s):  
Rotation Angle ◽  
Rotation Axis ◽  
Axial Direction ◽  
The Other ◽  
Rotation Vector ◽  
Coordinate Transformations ◽  
Rotation Axes ◽  
Analytic Expressions ◽  
Direction Cosines

An analysis of compound rotations, such as occur in eulerian cradles, is presented in terms of a calculus of rotation axes, without reference to the associated coordinate transformations. The general case of three rotation shafts mounted on one another, with any relation between them at datum zero, is presented. The problem and its solution may be represented entirely in terms of a plane octagon in which four sides have directions that are instrumental constants and the other four sides have lengths that are instrumental constants. When the first four sides are given lengths that express both the rotation angle and the axial direction of the required rotation, then the remaining four sides have directions that directly express the rotations in the drive shafts, that will generate the required rotation. Analytic expressions are given for the shaft setting angles in the general case. If the first and third axes are parallel and the intermediate one perpendicular to these at datum zero (as in the four-circle diffractometer) then these reduce to θ 1 = arctan ( μ, σ ) + [arctan ( λ , v ) - ψ -½8π], θ 2 = 2 s arcsin ( λ 2 + v 2 )½, θ 3 = ( μ, σ ) - [arctan ( λ , v ) - ψ - ½8π], s = ± 1, 0 ≤ arcsin ( λ 2 + v 2)½ ≤ ½π, in which λ, μ, v and σ are the four components of a rotation vector constructed such that λ, μ and v are the direction cosines of the rotation axis multiplied by sin½ θ for a rotation angle θ and σ is cos½ θ . ψ is a constant determined by the choice of directions to which λ and v are measured. The results for the general case are also expressed in terms of more conventional variables.

scholarly journals Crystal structure of trihydrogen bis{[1,1,1-tris(2-oxidoethylaminomethyl)ethane]cobalt(III)} trinitrate

2015 ◽  
Vol 71 (12) ◽  
pp. m275-m276 ◽  
Author(s):  
Waqas Sethi ◽  
Heini V. Johannesen ◽  
Thorbjørn J. Morsing ◽  
Stergios Piligkos ◽  
Høgni Weihe
Keyword(s):  
Crystal Structure ◽  
Hydrogen Bonding ◽  
Network Structure ◽  
Title Compound ◽  
Rotation Axis ◽  
Three Dimensional ◽  
Rotation Axes ◽  
Dimensional Network ◽  
Nitrate Anions

The title compound, [Co2(L)2]3+·3NO3−[whereL= CH3C(CH2NHCH2CH2OH1/2)3], has been synthesized from the ligand 1,1,1-tris(2-hydroxyethylaminomethyl)ethane. The cobalt(III) dimer has an interesting and uncommon O—H...O hydrogen-bonding motif with the three bridging hydroxy H atoms each being equally disordered over two positions. In the dimeric trication, the octahedrally coordinated CoIIIatoms and the capping C atoms lie on a threefold rotation axis. The N atoms of two crystallographically independent nitrate anions also lie on threefold rotation axes. N—H...O hydrogen bonding between the complex cations and nitrate anions leads to the formation of a three-dimensional network structure. The compound is a racemic conglomerate of crystals containing either D or L molecules. The crystal used for this study is a D crystal.

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