Stereo cameras have been widely used for three-dimensional (3D) imaging, and their performances are highly depended on the calibration accuracy. This paper presents a marked-crossed fringe pattern for the calibration ...
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Stereo cameras have been widely used for three-dimensional (3D) imaging, and their performances are highly depended on the calibration accuracy. This paper presents a marked-crossed fringe pattern for the calibration of stereo cameras. Some coded markers are also encoded into the crossed fringe pattern, and the feature points are encoded into the carried phase. Two wrapped phase maps are recovered by using the Fourier transform, and the markers are extracted and decoded for absolute phase unwrapping. Referring to the absolute phase values, the one-to-one mapping between the world points and the image points can be established to calibrate the stereo cameras. Compared with the traditional method, the proposed method adopts global coding, which can flexibly select any part of the feature points for calibration and obtain high-precision camera parameters. Simulations and experiments show the effectiveness of the method.
Non-contact optical measurement methods have been widely used in the fields of three-dimensional (3D) machine vision and photogrammetry attributed to their advantages of high precision, high speed and low cost. The ca...
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Non-contact optical measurement methods have been widely used in the fields of three-dimensional (3D) machine vision and photogrammetry attributed to their advantages of high precision, high speed and low cost. The calibration results directly affect the accuracy of the vision measurement system. Most of the existing calibration methods with two-dimensional (2D) targets need all of the feature points to be captured by the camera, otherwise it would be difficult to distinguish them due to the usage of identical feature points. This paper presents an active calibration target that consists of phase-shifting wedge gratings (PWGs) with three different periods and globally coded on the basis of rotation invariant local binary pattern (LBP) coding. Feature points are the intersections of several straight lines fitted by the 0 and pi phase points. The sub-pixel coordinates can be accurately obtained with the phase-shifting method and the windowed linear fitting. Each feature point has its corresponding label to determine its specific position, therefore the one-to-one correspondence between the image coordinates and world coordinates can be obtained even the images are partially captured, and this characteristic can expand the flexibility in both monocular and multi-camera calibrations. In addition, owing to the phase-shifting method, calibration can be accomplished when the camera is defocused. Simulations and experiments further prove the flexibility and robustness of the proposed method.
The parent-child interaction strongly influences the emotional, behavioural, and cognitive development of young children. The nature of parent-child interactions differs in families with children with autism spectrum ...
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The parent-child interaction strongly influences the emotional, behavioural, and cognitive development of young children. The nature of parent-child interactions differs in families with children with autism spectrum disorder (ASD), but research still entails a lot of inconsistencies and there is no consensus as to how these interactions should be coded. The parent-child interaction between sixteen mothers and their child with ASD (M (age) = 68 months) and a younger sibling without ASD (M (age) = 48 months) in a within-family study were coded using both a global and frequency coding scheme. global and frequency codes of the same sample were compared to explore the value of each coding method and how they could complement each other. In addition, each coding method's ability to detect group differences was evaluated. We found that mothers used an interaction style characterized by more support and structure, and clearer instructions in interaction with their children without ASD. In addition, global rating results suggested that within the ASD group, mothers may adapt their behaviour to the specific abilities of their child. Regarding the evaluation of coding method, results showed overlap between conceptually similar constructs included in both coding schemes. Although frequency coding clearly has its value, more qualitative aspects of the interaction were better captured by global rating scales and global rating was more time efficient. For this purpose, global ratings might be preferable over frequency coding.
A new framework has been developed to express variant and invariant properties of functions operating on a binary vector *** framework allows for manipulation of dynamic logic using basic operations and *** representa...
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A new framework has been developed to express variant and invariant properties of functions operating on a binary vector *** framework allows for manipulation of dynamic logic using basic operations and *** representations of binary functional spaces are *** ideas of binary functional spaces are extended and additional conditions are added to describe new function representation schemes:F code and C *** of the proposed functional space representation schemes were *** was found that the complete representation for any set of functions operating on a binary sequence of numbers is larger than previously *** complete representation can only be described using a structure having a space of size 2^(2n)×2^(n)!for any given space of functions acting on a binary sequence of length *** framework,along with the proposed coding schemes provides a foundational theory of variant and invariant logic in software and electricelectronic technology and engineering,and has uses in the analysis of the stability of rule-based,dynamic binary systems such as cellular automata.
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