Curvilinear Objects Research Articles

Curvilinear object segmentation in medical images based on ODoS filter and deep learning network

Curvilinear object segmentation in medical images based on ODoS filter and deep learning network

Chirality coupling in topological magnetic textures with multiple magnetochiral parameters

Chiral effects originate from the lack of inversion symmetry within the lattice unit cell or sample’s shape. Being mapped onto magnetic ordering, chirality enables topologically non-trivial textures with a given handedness. Here, we demonstrate the existence of a static 3D texture characterized by two magnetochiral parameters being magnetic helicity of the vortex and geometrical chirality of the core string itself in geometrically curved asymmetric permalloy cap with a size of 80 nm and a vortex ground state. We experimentally validate the nonlocal chiral symmetry breaking effect in this object, which leads to the geometric deformation of the vortex string into a helix with curvature 3 μm−1 and torsion 11 μm−1. The geometric chirality of the vortex string is determined by the magnetic helicity of the vortex texture, constituting coupling of two chiral parameters within the same texture. Beyond the vortex state, we anticipate that complex curvilinear objects hosting 3D magnetic textures like curved skyrmion tubes and hopfions can be characterized by multiple coupled magnetochiral parameters, that influence their statics and field- or current-driven dynamics for spin-orbitronics and magnonics.

Development of a user interface for input of a curvilinear object movement trajectory with variable speed

The article considers the development of an interface for the most accurate input by the user of the trajectory of the curvilinear movement of the ship in the marine environment with variable speed for the further development of software for modeling the marine water area. Convenient modeling of objects in the sea water area requires a convenient interface that allows the user not only to set an arbitrary curvilinear trajectory of movement, but also checks the possibility of movement of the given object in relation to its size and speed of movement. Therefore, for the implementation of an interactive interface for entering a curvilinear trajectory of a ship, it is necessary to take into account the dynamics of the controlled object. When evaluating the trajectory, the physical limitations of the vessel must be satisfied. They determine the minimum radius of curvature, tangential acceleration and all three speeds (longitudinal, transverse, angular). The projected trajectory should be smooth, and its speeds along all three axes should be constant. Taking into account information about the physical forces affecting the movement of the ship, the formulas for calculating the points of the trajectory were derived, which are subsequently used both for visual representation and for calculations in the simulation of the experiment. The problem was divided to 3 parts: linear movement, the movement along the arc of the circle, movement after the turn. The algorithm for getting the position of the ship at any point of time during the turn was provided/. The article also provides an example of coding derived formulas using C# programming language. The results were provided by demonstrating the developed interface.

Reliability of results obtained by semi-analytical finite element method for prismatic bodies with variable physical and geometric parameters

To confirm the reliability of the results obtained on the basis of the semi-analytical finite element method using the approaches suggested in [1-2, 4-6], a wide range of test problems is considered. Within the framework of the elastic approach, the spatial problem of an unevenly loaded shell, the middle surface of which has the shape of an elliptical paraboloid, is considered. The validation of the reliability of solutions obtained on the basis of the semi-analytical finite element method for physically nonlinear problems is carried out using the example of elastic-plastic calculation of an unevenly heated cube, the physical and mechanical characteristics of the material of which depend on temperature. To substantiate the reliability of the results obtained when solving problems of large plastic deformations, the elastic-plastic deformation of a parallelepiped between plane-parallel plates in the absence of contact friction is considered.
 The efficiency of application of the semi-analytical finite element method to the calculation of curvilinear inhomogeneous prismatic objects is shown. The solution of the control problems of the theory of elasticity, thermoelasticity and thermoplasticity, as well as the problems of shape change, makes it possible to draw a conclusion about the reliability of the results of the study of the selected class of objects on the basis of the developed methodology and the applied software package that implements it.

Series Photothermoelectric Coupling Between Two Composite Materials for a Freely Attachable Broadband Imaging Sheet

As flexible wearable sensors and imagers are receiving attention from diverse social sectors, the freely attachable photothermoelectric (PTE) conversion technique should be evaluated to develop a highly usable safety sensor network. Although carbon nanotube (CNT)‐related materials should be effective, the key parameters/structures that maximize PTE conversion have not been clarified, thus hindering optimum device design and practical use. Herein, the flexible, sensitive broadband photodetection operation based on a coupling configuration between the CNT film photo/heat/electron channel and metal electrode is evaluated. Experimental PTE measurements and steady‐state thermal distribution simulations reveal that a series coupling of a p‐type CNT film channel and a highly negative Seebeck coefficient counter metal electrode facilitate superior photodetection performances than those of a parallel coupling configuration. Furthermore, subsequent device designs provide sensitive broadband photodetection from the millimeter‐wave to visible light wavelength regions with a minimum noise equivalent power of 5 pWHz−1/2 in an uncooled nonvacuum condition. Simultaneously, the mechanical flexibility of the proposed photodetector allows for its use in freely attachable sheet imager applications on curvilinear objects, and the nondestructive 3D photomonitoring of a defective intricately bent sample is demonstrated.

Semi-analytical method of finished elements in elastic and elastic-plastic position for curviline prismatic objects

In [4, 5, 6] the algorithm of the method of block iterations of solving linear and nonlinear equations by the semivanalytic finite element method for curvilinear inhomogeneous prismatic bodies is realized. This paper presents the results of the effectiveness of the semi-analytical finite element method for the consideration of curvilinear prismatic objects in elastic and elastic-plastic formulation.
 The choice of the optimal in terms of machine time and speed of convergence of the iterative process algorithm for solving systems of linear and nonlinear equations by the semivanalytic finite element method [1, 2, 3] is an important factor influencing the efficiency of the method as a whole. Numerous studies have shown that using the block iteration method to solve systems of equations of the semivanalytic finite element method for prismatic bodies with variable parameters has a number of important advantages over solving systems of the traditional variant of the finite element method.
 The organization of the computational process and its software implementation takes into account the basic requirements for software for calculating strength on modern software packages. The modular structure of the developed system of programs provides its non-closedness concerning new classes of tasks.
 The use of the block iteration method to solve systems of nonlinear equations of SAFEM is approximately an order of magnitude superior to the traditional finite element method.

Faces under continuous flash suppression capture attention faster than objects, but without a face-evoked steady-state visual potential: Is curvilinearity responsible for the behavioral effect?

Face perception is a vital part of human social interactions. The social value of faces makes their efficient detection evolutionarily advantageous. It has been suggested that this might occur nonconsciously, but experimental results are equivocal thus far. Here, we probe nonconscious face perception using a novel combination of binocular rivalry with continuous flash suppression and steady-state visually evoked potentials. In the first two experiments, participants viewed either non-face objects, neutral faces (Study 1), or fearful faces (Study 2). Consistent with the hypothesis that faces are processed nonconsciously, we found that faces broke through suppression faster than objects. We did not, however, observe a concomitant face-selective steady-state visually evoked potential. Study 3 was run to reconcile this paradox. We hypothesized that the faster breakthrough time was due to a mid-level visual feature, curvilinearity, rather than high-level category membership, which would explain the behavioral difference without neural evidence of face-selective processing. We tested this hypothesis by presenting participants with four different groups of stimuli outside of conscious awareness: rectilinear objects (e.g., chessboard), curvilinear objects (e.g., dartboard), faces, and objects that were not dominantly curvilinear or rectilinear. We found that faces and curvilinear objects broke through suppression faster than objects and rectilinear objects. Moreover, there was no difference between faces and curvilinear objects. These results support our hypothesis that the observed behavioral advantage for faces is due to their curvilinearity, rather than category membership.

INTERPOLATION AND APPROXIMATION BY RATIONAL CURVES OF BEZIER AND NURBS-CURVES

Relevance. Rational Bezier curves and NURBS curves are widely used in modeling curvilinear objects due to the great flexibility and efficiency of the method. Therefore, it is relevant to develop an interpolation method and approximation by these curves of a discrete series of points both in the plane and in three-dimensional space. Method. The work is devoted to the development of a new approach to interpolation and approximations curve fitting, represented by a set of discrete points. The analytical description of the desired curve is implemented using a rational Bezier curve and a NURBS-curve. To solve this problem, two approaches are proposed. The first approach is that the weights of the points are set in advance and then the coordinates of the points of the interpolating or approximating rational Bezier curve as well as the NURBS-curve are calculated. The second approach is that the coordinates of the points are set in advance and then the weights of the control points of the Bezier curve as well as the NURBS-curve are calculated. At the beginning of the process, are set not only coordinates, but also parameters are set to a discrete row of points, that is, each point has the following definition: T (x, y, u) on the plane or T (x, y, z, u) in the three-dimensional space, where u - parameter. To solve the interpolation problem, a system of linear equations is created in which each equation reflects the equality between the analytical formula for a curve and a given point. Moreover, the number of interpolated points cannot be more than the order of the interpolating curve. Thus, we have a system of N linear equations, where N is the number of points equal to the number of points of the curve. Unknown are N control points of the desired curve. Moreover, in the first approach, the unknowns are coordinates of control points, and in the second weights of points.To solve the approximation problem, the Least Squares method is used. In the beginning, a sum of squared functional of the terms of the differences between the analytic formula of the curve and the coordinate of the given point is created. The optimization problem of minimizing this functional is solved. For this, a system of linear equations is created., each equation of which is a derivative of the functional with respect to a given parameter and equated to zero. In the first approach, the desired parameters are the coordinates of points, and in the second weights of points. Results.Two methods of interpolation and approximation of a point series by rational Bezier curves and NURBS-curves were developed. Conclusions. The test cases carried out using computer programs and visualization of results confirm the validity of the proposed methods.

Verification of the spline method and its application to curvilinear objects

Czasopismo Techniczne » 2019 » Volume 1 » Verification of the spline method and its application to curvilinear objects A A A

ROAD NETWORK IDENTIFICATION AND EXTRACTION IN SATELLITE IMAGERY USING OTSU'S METHOD AND CONNECTED COMPONENT ANALYSIS

Abstract. As the high resolution satellite images have become easily available, this has motivated researchers for searching advanced methods for object detection and extraction from satellite images. Roads are important curvilinear object as they are a used in urban planning, emergency response, route planning etc. Automatic road detection from satellite images has now become an important topic in photogrammetry with the advances in remote sensing technology. In this paper, a method for road detection and extraction of satellite images has been introduced. This method uses the concept of histogram equalization, Otsu's method of image segmentation, connected component analysis and morphological operations. The aim of this paper is to discover the potential of high resolution satellite images for detecting and extracting the road network in a robust manner.

Shearlets and sparse representation for microresistivity borehole image inpainting

Microresistivity image logs from wireline tools commonly include nonmeasured gaps corresponding to the spaces between electrode-carrying pads in contact with the borehole wall. The missing data impede the development of automated processes that seek to provide objective and reproducible geologic analysis. Geologic features often manifest themselves as curvilinear objects representing a variety of discontinuities, such as layer boundaries and fractures, which lend themselves to sparse representation. Missing data may be inpainted by thresholding or minimizing the norm of their representation in a fitting dictionary. Curvelets have been found to provide good sparse approximation for these features, but shearlets are shown to be more computationally efficient. Results from a mix of synthetic and field image logs indicate more accurate reconstruction of sharp high-contrast edges.

Tilt-less 3-D electron imaging and reconstruction of complex curvilinear structures

The ability to obtain three-dimensional (3-D) information about morphologies of nanostructures elucidates many interesting properties of materials in both physical and biological sciences. Here we demonstrate a novel method in scanning transmission electron microscopy (STEM) that gives a fast and reliable assessment of the 3-D configuration of curvilinear nanostructures, all without needing to tilt the sample through an arc. Using one-dimensional crystalline defects known as dislocations as a prototypical example of a complex curvilinear object, we demonstrate their 3-D reconstruction two orders of magnitude faster than by standard tilt-arc TEM tomographic techniques, from data recorded by selecting different ray paths of the convergent STEM probe. Due to its speed and immunity to problems associated with a tilt arc, the tilt-less 3-D imaging offers important advantages for investigations of radiation-sensitive, polycrystalline, or magnetic materials. Further, by using a segmented detector, the total electron dose is reduced to a single STEM raster scan acquisition; our tilt-less approach will therefore open new avenues for real-time 3-D electron imaging of dynamic processes.

General-purpose curvilinear object detection with fuzzy mathematical morphology

Curvilinear object detection is the common denominator of several applications. Some illustrative examples are road detection from aerial or satellite images, human airways from volumetric 3D scans or vascular structures in eye-fundus images. In this work, we propose two general-purpose curvilinear object detectors that may serve as building blocks for application-specific systems. To do so, we employ fuzzy mathematical morphology operators due to their robustness with respect to uncertainty and noise, and the trade-off they offer between expressive power and computational requirements. The extraction of linear features is based on, respectively, the fuzzy hit-or-miss transform and the fuzzy top-hat transform. They can be customized depending on the width of the objects of interest. We compare these two approaches with other state-of-the-art, general-purpose curvilinear object detectors to highlight their strengths and shortcomings. Both detectors succeed at localizing the objects of interest in different greyscale images.

Curvilinear Structure Analysis by Ranking the Orientation Responses of Path Operators.

The analysis of thin curvilinear objects in 3D images is a complex and challenging task. In this article, we introduce a new, non-linear operator, called RORPO (Ranking the Orientation Responses of Path Operators). Inspired by the multidirectional paradigm currently used in linear filtering for thin structure analysis, RORPO is built upon the notion of path operator from mathematical morphology. This operator, unlike most operators commonly used for 3D curvilinear structure analysis, is discrete, non-linear and non-local. From this new operator, two main curvilinear structure characteristics can be estimated: an intensity feature, that can be assimilated to a quantitative measure of curvilinearity; and a directional feature, providing a quantitative measure of the structure's orientation. We provide a full description of the structural and algorithmic details for computing these two features from RORPO, and we discuss computational issues. We experimentally assess RORPO by comparison with three of the most popular curvilinear structure analysis filters, namely Frangi Vesselness, Optimally Oriented Flux, and Hybrid Diffusion with Continuous Switch. In particular, we show that our method provides up to 8 percent more true positive and 50 percent less false positives than the next best method, on synthetic and real 3D images.

A survey on curvilinear object segmentation in multiple applications

Curvilinear object segmentation is a paramount step for many applications ranging from medical to aerial image processing. In particular, vessel segmentation in retinal images, detection of spiculated lesions in mammograms or extraction of airways in CT scans provide essential information to experts to evaluate, diagnose and propose a treatment. The significance of these applications has conducted important efforts to propose curvilinear object segmentation algorithms based on the most different techniques. The main objective of this review is to clearly present the similarities and differences between curvilinear structures in different applications and the different techniques used to segment them more effectively. To do so, we propose a general definition of curvilinear structures that encompasses the distinct models considered in the literature. In addition, we analyse and classify the mathematical techniques used to segment the curvilinear structures found across all considered applications, studying their strengths and weaknesses. In particular, we present the most relevant benchmarks related to curvilinear object segmentation as well as the best algorithms according to several performance measures. By doing so, it is acquired a wider point of view to extend the results from some fields to others, and to understand under which conditions some methodologies should be favoured over the rest of them.

Terrain based co‐operative UAV mapping of complex obstacles using 2‐D splinegon

PurposeThis paper aims to describe a recently proposed algorithm in terrain‐based cooperative UAV mapping of the unknown complex obstacle in a stationary environment where the complex obstacles are represented as curved in nature. It also aims to use an extended Kalman filter (EKF) to estimate the fused position of the UAVs and to apply the 2‐D splinegon technique to build the map of the complex shaped obstacles. The path of the UAVs are dictated by the Dubins path planning algorithm. The focus is to achieve a guaranteed performance of sensor based mapping of the uncertain environments using multiple UAVs.Design/methodology/approachAn extended Kalman filter is used to estimate the position of the UAVs, and the 2‐D splinegon technique is used to build the map of the complex obstacle where the path of the UAVs are dictated by the Dubins path planning algorithm.FindingsThe guaranteed performance is quantified by explicit bounds of the position estimate of the multiple UAVs for mapping of the complex obstacles using 2‐D splinegon technique. This is a newly proposed algorithm, the most efficient and a robust way in terrain based mapping of the complex obstacles. The proposed method can provide mathematically provable and performance guarantees that are achievable in practice.Originality/valueThe paper describes the main contribution in mapping the complex shaped curvilinear objects using the 2‐D splinegon technique. This is a new approach where the fused EKF estimated positions are used with the limited number of sensors' measurements in building the map of the complex obstacles.

Some consonants sound curvy: Effects of sound symbolism on object recognition

Two experiments explored the influence of consonant sound symbolism on object recognition. In Experiment 1, participants heard a word ostensibly from a foreign language (in reality, a pseudoword) followed by two objects on screen: a rectilinear object and a curvilinear object. The task involved judging which of the two objects was properly described by the unknown pseudoword. The results showed that congruent sound-symbolic pseudoword-object pairs produced higher task accuracy over three rounds of testing than did incongruent pairs, despite the fact that "hard" pseudowords (with three plosives) and "soft" pseudowords (with three nonplosives) were paired equally with rectilinear and curvilinear objects. Experiment 2 reduced awareness of the manipulation by including similar-shaped, target-related distractors. Sound symbolism effects still emerged, though the time course of these effects over three rounds differed from that in Experiment 1.

Variable Length Open Contour Tracking Using a Deformable Trellis

This paper focuses on contour tracking, an important problem in computer vision, and specifically on open contours that often directly represent a curvilinear object. Compelling applications are found in the field of bioimage analysis where blood vessels, dendrites, and various other biological structures are tracked over time. General open contour tracking, and biological images in particular, pose major challenges including scene clutter with similar structures (e.g., in the cell), and time varying contour length due to natural growth and shortening phenomena, which have not been adequately answered by earlier approaches based on closed and fixed end-point contours. We propose a model-based estimation algorithm to track open contours of time-varying length, which is robust to neighborhood clutter with similar structures. The method employs a deformable trellis in conjunction with a probabilistic (hidden Markov) model to estimate contour position, deformation, growth and shortening. It generates a maximum a posteriori estimate given observations in the current frame and prior contour information from previous frames. Experimental results on synthetic and real-world data demonstrate the effectiveness and performance gains of the proposed algorithm.

Extraction of centre line from curvilinear objects

AbstractThis tutorial paper surveys three methods designed to detect the centre line in curvilinear structures. These are the iterative thinning, Steger’s and derivatives’ methods. We aim to illustrate the effectivness of the chosen methods for processing laser-trace images and magnetic resonance slices of human head. The essence of each three methods is presented and important parameters are discussed. Experiments have been carried out and results are discussed in the light of the quality of the centre line produced and work time of all three methods.

Airborne Vehicle Mapping of Curvilinear Objects Using 2-D Splinegon

This paper describes a recently proposed algorithm in mapping the unknown obstacle in a stationary environment where the obstacles are represented as curved in nature. The focus is to achieve a guaranteed performance of sensor-based navigation and mapping. The guaranteed performance is quantified by explicit bounds of the position estimate of an autonomous aerial vehicle using an extended Kalman filter to track the obstacle and extract its map. The Dubins path planning algorithm is used to provide a flyable and safe path to the vehicle to fly from one location to another. The 2-D Splinegon technique is presented for the mapping of the unknown complex obstacles. This Splinegon technique, which is the most efficient and a robust way to estimate the boundary of a curved-nature obstacles, can provide mathematically provable performance guarantees that are achievable in practice.