Boundary Tracking Method Research Articles

Studying a matching method combining distance proximity and buffer constraints

Abstract In order to achieve fast matching of global navigation satellite system (GNSS) track data and vector road network data, a rough-to-fine matching method combining distance proximity and buffer constraints is studied. The GNSS track data is preprocessed: A rasterisation method is used to eliminate the low-quality track data and obtain the binary graph; then, the road centrelines are obtained by a skeleton extraction method; the thinning data is converted into line segments or closed lines starting from nodes by the boundary tracking method, which is stored in the vector form. Finally, the boundary tracking method is used to convert the thinning data into closed lines and store them in the vector form. A two-layer rough-to-fine matching strategy is applied: First, the changing state of the road arc is determined according to the rough matching strategy of road segment distance. Next, according to the buffer constraint criterion, a rectangular or circular buffer is selected to achieve precise matching of road network data. The results show that the proposed method has good matching effect, which is especially suitable for working with more GNSS track data.

A generalized line segmentation method for multi-script handwritten text documents

Handwritten document image segmentation into text-lines is a crucial stage towards unconstrained handwritten document recognition. In the context of Indian subcontinent various scripts are used for communication where a system for multi-script handwritten text line segmentation is very much essential. This paper presents a multi-script text line segmentation algorithm based on newly developed light projection, start point detection, and boundary tracking methods. The proposed approach is capable of overcoming most of the hindrance faced by state-of-the-art methods. The experiment is performed on our proposed Bangla handwritten document image dataset WBSUBNdb_text and also on a variety of well-known public handwritten datasets namely: CMATERdb, PhDIndic_11, KHATT, HIT-MW, ISI Bengali Writer Identification/Verification dataset, ICDAR 2013 segmentation contest dataset, ICDAR 2013 writer identification contest benchmark dataset, and obtained promising results.

Relaxed decoupled direct calculation of voltage collapse points and its application in static voltage stability region boundary formation

Static voltage stability is critical for the operation of power grids. With the penetration of renewable energies, region-based method become a choice to present the stability of a power grid. Static voltage stability region is hence a useful and intuitive tool to determine the safety margin of a power grid. The formation of static voltage stability region is however time consuming. To overcome such issue, this work proposes a relaxed decoupled direct calculation (RDDC) method to find voltage collapse points (VCPs). The direct calculation of VCPs is a Newton-Raphson type method and faces the sensitivity issue of the initial values. Boundary tracking method provides a framework to utilize the information from neighbor VCPs and hence is integrated with the proposed RDDC method. The results show that the RDDC method is able to calculating VCPs as precise as continuation power flow with less computational time. When RDDC is integrated with boundary tracking, results show that the static voltage stability region boundary can be generated with high precision, and computational performance improvement can be observed for all the test systems from nine buses to ten thousand of buses. This demonstrates the applicability and scalability of the proposed method to power systems with different scales.

Real-Time Mine Road Boundary Detection and Tracking for Autonomous Truck.

Road boundary detection is an important part of the perception of the autonomous driving. It is difficult to detect road boundaries of unstructured roads because there are no curbs. There are no clear boundaries on mine roads to distinguish areas within the road boundary line and areas outside the road boundary line. This paper proposes a real-time road boundary detection and tracking method by a 3D-LIDAR sensor. The road boundary points are extracted from the detected elevated point clouds above the ground point cloud according to the spatial distance characteristics and the angular features. Road tracking is to predict and update the boundary point information in real-time, in order to prevent false and missed detection. The experimental verification of mine road data shows the accuracy and robustness of the proposed algorithm.

Accelerated Piston Problem and High Order Moving Boundary Tracking Method for Compressible Fluid Flows

Reliable tracking of moving boundaries is important for the simulation of compressible fluid flows, and there are a lot of contributions in literature. We recognize from the classical piston proble...

Fast Specimen Boundary Tracking and Local Imaging with Scanning Probe Microscopy.

An efficient and adaptive boundary tracking method is developed to confine area of interest for high-efficiency local scanning. By using a boundary point determination criterion, the scanning tip is steered with a sinusoidal waveform while estimating azimuth angle and radius ratio of each boundary point to accurately track the boundary of targets. A local scan region and path are subsequently planned based on the prior knowledge of boundary tracking to reduce the scan time. Boundary tracking and local scanning methods have great potential not only for fast dimension measurement but also for sample surface topography and physical characterization, with only scanning region of interest. The performance of the proposed methods was verified by using the alternate current mode scanning ion-conductance microscopy, tapping, and PeakForce modulation atomic force microscopy. Experimental results of single/multitarget boundary tracking and local scanning of target structures with complex boundaries demonstrate the flexibility and validity of the proposed method.

A 3-D Nonhomogeneous FE Model of Human Fingertip Based on MRI Measurements

A 3-D nonhomogeneous finite-element (FE) dynamic model of a primate fingertip is developed in this paper based on magnetic resonance (MR) imaging measurements for better understanding the mechanism of human finger sensation. The geometries of a human fingertip are measured using an MR system, and a series of 2-D images is obtained. Utilizing a boundary tracking method, boundaries of the fingertip and distal phalanx are tracked from each image slice and a set of boundary nodes is generated to construct a 3-D tetrahedral mesh of the fingertip. The 3-D mesh is then utilized to formulate a nonhomogeneous FE dynamic model for simulating the fingertip behaviors. The constitutive model, which consists of elastic and viscous elements, is employed to govern the dynamic behaviors of individual tetrahedral FE. The FE model is further extended to deal with contact interaction between the fingertip and an external instrument. Differing with conventional fingertip models, the model presented in this paper is able to not only better represent internal and external geometries of a human fingertip but also take the tissue viscosity into consideration. Simulation and experiments are performed with both a human finger and a fingertip phantom under different indentation operations. We found that the Voigt model can simulate the force behaviors of a fingertip phantom but has difficulty to reproduce the force relaxation behavior of a human fingertip. We have therefore introduced a parallel five-parameter physical model to solve this problem.

Double-Diffusive Convection on the Solid-Liquid Interface in the Early Stage of Solidification

In the present study, we report on the effect of double diffusive convection associated with solute discharge in the early stage of unidirectional solidification from above. Two-dimensional numerical simulations have been conducted to clarify the concentration, temperature and heat flux on the solid-liquid interface under a constant solid layer growth rate. The moving boundary due to solid layer growth was formulated according to the boundary tracking method. The simulations were conducted by varying the initial conditions; concentration, solid layer growth rate and heating temperature at the bottom. The effects of thermal and solutal Rayleigh number on the concentration and the convective heat flux at the solid-liquid boundary were discussed, and the associated correlations to predict those values as functions of the initial thermal and solutal Rayleigh numbers as well as the speeds of solidification were derived.

A Boundary Tracking Method Based on Topological Relation & Region Growing

This paper proposed a method to measure destructive pavement area based on region growing and topological relation. Firstly, separate the image of smeary area and calibrate plate area according to the image of topological relations. Then, the closed boundary could be achieved by utilizing the algorithms of region growing and boundary tracking, and the pixels in this area could be calculated. Finally, the practical area can be calculated through the ratio relation between the area and the calibrate plate. It’s demonstrated through experiments that the method has low time complexity and high robust.

A Precise Eye Localization Method Based on Ratio Local Binary Pattern

A novel method for human eye location is proposed in this paper, which is designed based on an improved algorithm called ratio local binary pattern (RLBP). These patterns provide a simple but powerful spatial description of eye texture and have low cost of calculation. The working principle of RLBP is described in detail, and based on it a system is developed. The eye location system is composed of three parts namely face detection, eye windows detection and precise eye location. In the face detection stage, AdaBoost method is used to search for the pure face region and crop it from the facial image. Then the RLBP encoding and gray projection are conducted on the pure face and two eye windows are got. After these steps, the boundary tracking and centriod method are adopt for the precise eye location, all the eyes located are annotated and drawn a rectangular box around the center. The experiment has been carried out on a wide set of images extracted from databases, and it shows that the algorithm of eye location is efficient and robust.

TU-D-304A-08: A Novel Boundary Tracking Method for Metal Artifact Suppression in Helical CT Imaging

Purpose: One of the major challenges for metal artifact suppression in CT lies in the accurate detection of metal regions either in image space or projection space. In this work, we proposed a novel, semi-automatic boundary tracking scheme based on dual-front active contour models and boundary mapping strategy to detect the metal regions on reformatted projection data, and to effectively suppress metal artifacts on reconstructed images. Methods and Materials: We first created reformatted projections from multi-slice helical scan by combining data at the same angle view over the full longitudinal scan range. The shapes, locations, and number of metal objects can be easily identified from every single reformatted projection. Since the shape of the metal projections only changes slightly between adjacent projections, the segmented boundary from the first reformatted projections can be mapped to the next projection, and used as the initialization of the dual-front active contour model to find the actual metal object boundary in the current projection within only a couple of iterations with an automatic stop criterion. After detecting the metal implants on all the reformatted projections, a Delaunay triangulation was applied to fill the metal shadows. Finally, the image was reconstructed using commercially available reconstruction algorithms for multi-slice helical CT. Results: Patient studies were performed to evaluate the proposed method. Four cases were corrected, including three abdominal exams with hip prosthesis, and one musculoskeletal exam with shoulder prosthesis. The results demonstrated that the proposed method can suppress metal artifacts efficiently and effectively. Conclusions: A novel boundary tracking method was proposed for metal artifact suppression in multi-slice helical CT. This method incorporates the information of shape and location of metal implants into the boundary tracking procedure, which can handle multiple metal implants with various sizes and shapes, and can improve the segmentation accuracy and artifact suppression.

Anisotropic grain growth with pore drag under applied loads

In the final stage of sintering of ceramics, residual pores co-evolve with grain boundaries because of incomplete densification. Their interactions coupled with external loads are critical to the microstructural evolution of structural ceramics. A modified two-dimensional (2D) diffuse-interface phase field model, which differs from the boundary-tracking methods, is utilized to investigate the effects of stochastically distributed pore drag on grain growth kinetics and morphological evolution process of ceramics under applied loads. Contributions from both the boundary energy and elastic strain energy caused by pore drag forces and applied loading are incorporated in the modified phase field model to describe the isotropic or cubically anisotropic behaviors of polycrystalline materials. The temporal evolution of the spatially dependent grain orientation variables is determined by numerically solving non-linear Ginzburg–Landau equations using a semi-implicit Fourier-spectral method. Numerical results show that the anisotropic strain energy dominates the non-self-similar growth manner, leads to ordered grain morphologies and changes the growth rate.

Numerical analysis of moving boundary problems using the boundary tracking method

A new numerical scheme of the boundary tracking method for moving boundary problems is proposed. A key point of the scheme is to avoid concentration of tracking points on the moving boundary, and a convergence theorem is proved for the curve shortening problem. Some numerical examples for the curve shortening problem and the Hele-Shaw problem by the proposed scheme are shown.

Ray tracing deterministic 3-D fractals

As shown in 1982, Julia sets of quadratic functions as well as many other deterministic fractals exist in spaces of higher dimensionality than the complex plane. Originally a boundary-tracking algorithm was used to view these structures but required a large amount of storage space to operate. By ray tracing these objects, the storage facilities of a graphics workstation frame buffer are sufficient. A short discussion of a specific set of 3-D deterministic fractals precedes a full description of a ray-tracing algorithm applied to these objects. A comparison with the boundary-tracking method and applications to other 3-D deterministic fractals are also included.