Point Matching Technique Research Articles

A Hybrid Features Extraction on Face for Efficient Face Recognition

Image Processing is one of the vibrant research areas nowadays and particularly face recognition is given much importance in all the sectors. Accordingly this research paper proposes a hybrid Face Recognition System to find facial changes due to the aging factor in a robust manner. The highly qualified sharp features are extracted using the algorithms SURF(Speed Up Robust Features), HOG(Histogram of Oriented Gradient) and MSER(Maximally Stable Extremal Regions) to get better results. The proposed method divides the face into five regions. The whole face area is named Region1 can have a complete set of face features extracted using the SURF and it acts as a holistic feature. The Region 2, the nasal bridge features are extracted using the HOG. The Region 3 and Region 4 extract the features of the eyes of the face and the Region 5 extracts the features of the region around the nose and the mouth. The features of these regions are extracted using MSER. These different features from five regions are matched by point matching technique with the database of the target image. Experimental results are evaluated using the datasets such as Yale, FGNET and MORPH dataset. The experimental results show that the proposed face recognition algorithm is superior to traditional methods in terms of recognition rate and time complexity.

How adjustment could affect internal and marginal adaptation of CAD/CAM crowns made with different materials.

PURPOSERecently introduced hybrid and reinforced glass ceramic computer-aided design/computer-aided manufacturing (CAD/CAM) materials have been used for full-coverage restorations. However; the effect of adjustment and type of materials on internal and marginal adaptation are unknown. This study aimed to evaluate and compare the marginal and internal adaptations of crowns made of three different CAD/CAM materials before and after adjustment.MATERIALS AND METHODSOne acrylic resin maxillary first molar was prepared and served as the master die. Thirty-six restorations were fabricated using CAD/CAM system (CEREC Omnicam, MCXL) with three materials including lithium disilicate (IPS e.max CAD), zirconia-reinforced lithium silicate (Suprinity), and hybrid ceramic (Enamic). Internal and marginal adaptations were evaluated with the reference point matching technique before and after adjustment. The data were analyzed using mixed ANOVA considering α=.05 as the significance level.RESULTSThe effect of adjustment and its interaction with the restoration material were significant for marginal, absolute marginal, and occlusal discrepancies (P<.05). Before adjustment, Suprinity had lower marginal discrepancies than IPS e.max CAD (P=.18) and Enamic (P=.021); though no significant differences existed after adjustment.CONCLUSIONWithin the limitations of this study, crowns fabricated from IPS e.max CAD and Suprinity resulted in slightly better adaptation compared with Enamic crowns before adjustment. However, marginal, axial, and occlusal discrepancies were similar among all materials after the adjustment.

Diffusion-based isometric depth correspondence

We propose an iterative isometric point correspondence method that relies on diffusion distance to handle challenges posed by commodity depth sensors which usually provide incomplete and noisy surface data exhibiting holes and gaps. We formulate the correspondence problem as finding an optimal partial mapping between two given point sets, that minimizes deviation from isometry. Our algorithm starts with an initial rough correspondence between keypoints, obtained via any point matching technique. This initial correspondence is then pruned and updated by iterating a perfect matching algorithm until convergence in order to find as many reliable correspondences as possible. The resulting set of sparse but reliable correspondences then serves as a base matching from which a dense correspondence set is estimated. We additionally provide a global intrinsic symmetry detection technique which clusters a point cloud into its symmetric sides. We incorporate this technique into our point-based correspondence method so as to address the symmetrical flip problem and to further improve the reliability of our matching results. Our symmetry-aware correspondence method is especially effective on human shapes with global reflectional symmetry. We hence conduct experiments on datasets comprising human shapes and show that our method provides state of the art performance over depth frames exhibiting occlusions, large deformations, and topological noise.

RAPID: Measuring Deformation of Biological Tissues from MR Images Through the Riemannian Pseudo Kernel

Due to the nonlinear deformation of nonrigid and nonuniform tissues, it is challenging to accurately measure the displacements of feature points distributed on the inner parts, boundaries, and separatrices of tissue layers. To address this challenge, we propose a feature point matching technique called RAPID to measure MR 2D slice deformation of nonuniform and nonrigid biological tissues. We propose to use the covariance of several neighboring point statistics computed around a keypoint, as the keypoint descriptor. Inspired by the kernel methods, we advocate adopting a Riemannian pseudo kernel to map SPD matrices to a high dimensional Hilbert space, where the Euclidean geometry applies. We compare our RAPID with two existing schemes (i.e., SIFT and SURF). Our experimental results show that our RAPID is superior to SIFT and SURF, because the benefits offered by RAPID are two-fold. First, our RAPID increases the number of matched data points. Second, RAPID substantially improves the key-point matching accuracy of SIFT and SURF.

Point Matching Technique for Root Coverage Exposed by Visible Gingival Recession

Point Matching Technique for Root Coverage Exposed by Visible Gingival Recession

Moment method analysis of periodic array of thin conducting strips using waveguide simulator

In this paper, analysis of free-standing periodic array of thin conducting strips using waveguide simulator is presented. The method of moment is applied to numerically obtain its scattering parameters. With only two elements inside the waveguide simulator, scattering response of the infinite array illuminated by plane waves is accurately achieved. Coupled integral equations, due to the presence of two elements, are solved using pulse expansion and point matching technique. Numerically obtained results are compared with waveguide and plane wave simulations in CST MWS and measurement results for validation.

The comparison of topographic long profiles of gullies on Earth to gullies on Mars: A signal of water on Mars

The topographic signature of a landform can give important clues as to its formation process. Here, we have used topographic long profiles to study the process of gully formation on Mars. We studied topographic long profiles of gullies on Earth to (1) confirm that previously published generalisations of how long profile shape varies with process also applies at the kilometre-scale of martian gullies, and (2) use as a direct comparison with the martian data. We have compared 24 fluvial and 22 debris flow long profiles of terrestrial gullies derived from laser altimeter and GPS measurements, to 78 long profiles of a range of gullies on Mars derived from a stereo-photogrammetry point-matching technique. We have confirmed that this manual point-matching technique is reliable for the martian data by comparison with full digital elevation models. We used nine different characteristics of the long profiles, including slope and curvature parameters, to perform a canonical discriminant analysis, which allowed us to identify the variables most important for differentiating between fluvial and debris flow gullies on Earth. In agreement with published literature for larger-scale features, we found that terrestrial debris flow gullies tend to be steeper and less concave than fluvial gullies. We have found that gully long profiles on Mars can resemble long profiles of terrestrial gullies formed by either fluvial or debris flow processes, with slightly more affinity to fluvial systems. Gullies on Mars can only be weakly separated from those on Earth: they can be separated from terrestrial fluvial gullies on curvature parameters and from terrestrial debris flow gullies by slope parameters. In addition, we have found that different alcove types identified from planview morphology are also distinctive in terms of their long profile morphology: gullies which incise back into the bedrock are more similar to terrestrial debris flows whereas polar-pit gullies are most similar to terrestrial fluvial gullies. Our findings suggest that the presence of a bedrock alcove promotes debris flow behaviour in gullies on Mars.

RELATIVE POSE ESTIMATION USING IMAGE FEATURE TRIPLETS

Abstract. A fully automated reconstruction of the trajectory of image sequences using point correspondences is turning into a routine practice. However, there are cases in which point features are hardly detectable, cannot be localized in a stable distribution, and consequently lead to an insufficient pose estimation. This paper presents a triplet-wise scheme for calibrated relative pose estimation from image point and line triplets, and investigates the effectiveness of the feature integration upon the relative pose estimation. To this end, we employ an existing point matching technique and propose a method for line triplet matching in which the relative poses are resolved during the matching procedure. The line matching method aims at establishing hypotheses about potential minimal line matches that can be used for determining the parameters of relative orientation (pose estimation) of two images with respect to the reference one; then, quantifying the agreement using the estimated orientation parameters. Rather than randomly choosing the line candidates in the matching process, we generate an associated lookup table to guide the selection of potential line matches. In addition, we integrate the homologous point and line triplets into a common adjustment procedure. In order to be able to also work with image sequences the adjustment is formulated in an incremental manner. The proposed scheme is evaluated with both synthetic and real datasets, demonstrating its satisfactory performance and revealing the effectiveness of image feature integration.

Studies on some characteristics of rain-induced depolarization of Ku-band signal over an earth-space path at a tropical location

The rain-induced depolarization of a Ku-band satellite signal has been studied at a tropical location, Kolkata (22°34′N, 88°29′E). The depolarization phenomenon is observed in terms of an enhancement of cross-polar component of a horizontally polarized Ku-band satellite signal at the present location. The differential phase shifts, dominantly responsible for causing depolarization caused by scattering of oblate spheroidal rain drops at Ku-band, are computed by employing the point matching technique and utilizing rain drop size distribution data, experimentally obtained at the present location. The differential phase shift is significant for large rain drops resulting in greater depolarization of signal. Consequently, rain drop size distribution plays an important role in determining the depolarization of the satellite signal. The relationship of cross-polar enhancement with rain rate shows a seasonal variation indicating higher extent of depolarization during the pre-monsoon period than during the monsoon period, the reason being the dominance of larger rain drops in the pre-monsoon period compared to the monsoon months for identical rain rates.

A Learning Based Fiducial-driven Registration Scheme for Evaluating Laser Ablation Changes in Neurological Disorders.

In this work, we present a novel learning based fiducial driven registration (LeFiR) scheme which utilizes a point matching technique to identify the optimal configuration of landmarks to better recover deformation between a target and a moving image. Moreover, we employ the LeFiR scheme to model the localized nature of deformation introduced by a new treatment modality - laser induced interstitial thermal therapy (LITT) for treating neurological disorders. Magnetic resonance (MR) guided LITT has recently emerged as a minimally invasive alternative to craniotomy for local treatment of brain diseases (such as glioblastoma multiforme (GBM), epilepsy). However, LITT is currently only practised as an investigational procedure world-wide due to lack of data on longer term patient outcome following LITT. There is thus a need to quantitatively evaluate treatment related changes between post- and pre-LITT in terms of MR imaging markers. In order to validate LeFiR, we tested the scheme on a synthetic brain dataset (SBD) and in two real clinical scenarios for treating GBM and epilepsy with LITT. Four experiments under different deformation profiles simulating localized ablation effects of LITT on MRI were conducted on 286 pairs of SBD images. The training landmark configurations were obtained through 2000 iterations of registration where the points with consistently best registration performance were selected. The estimated landmarks greatly improved the quality metrics compared to a uniform grid (UniG) placement scheme, a speeded-up robust features (SURF) based method, and a scale-invariant feature transform (SIFT) based method as well as a generic free-form deformation (FFD) approach. The LeFiR method achieved average 90% improvement in recovering the local deformation compared to 82% for the uniform grid placement, 62% for the SURF based approach, and 16% for the generic FFD approach. On the real GBM and epilepsy data, the quantitative results showed that LeFiR outperformed UniG by 28% improvement in average.

Gaseous Slip-Flow Mixed Convection Through Ordered Microcylinders

The fully developed longitudinal slip-flow mixed convection between a periodic bunch of vertical microcylinders arranged in regular arrays is investigated in the present work. The two axially constant heat flux boundary conditions of H1 and H2 are considered in the analysis. The rarefaction effects are taken into consideration using first-order slip velocity and temperature jump boundary conditions. The method considered is mainly analytical, in that the governing equations and three of the boundary conditions are exactly satisfied. The remaining symmetry condition on the right-hand boundary of the typical element is applied to the solution through the point-matching technique. The results indicate that both the pressure drop and Nusselt number are not dependent on the type of the boundary conditions at small and moderate blockage ratios. At higher blockage ratios, the pressure drop is higher for the H2 case, whereas the opposite true for the Nusselt number. Furthermore, the pressure drop is an increasing function of the blockage ratio and a decreasing function of the Knudsen number. The same trend is observed for the Nusselt number, except at higher blockage ratios at which the functionality of this parameter on the blockage ratio may change.

Gaseous Slip Flow Mixed Convection in Vertical Microducts With Constant Axial Energy Input

The present investigation is devoted to the fully developed slip flow mixed convection in vertical microducts of two different cross sections, namely, polygon, with circle as a limiting case, and rectangle. The two axially constant heat flux boundary conditions of H1 and H2 are considered in the analysis. The velocity and temperature discontinuities at the boundary are incorporated into the solutions using the first-order slip boundary conditions. The method considered is mainly analytical in which the governing equations in cylindrical coordinates along with the symmetry conditions and finiteness of the flow parameter at the origin are exactly satisfied. The first-order slip boundary conditions are then applied to the solution using the point matching technique. The results show that both the Nusselt number and the pressure drop parameter are increasing functions of the Grashof to Reynolds ratio. It is also found that, with the exception of the H2 Nusselt number of the triangular duct, which shows an opposite trend, both the Nusselt number and the pressure drop are decreased by increasing the Knudsen number. Furthermore, the pressure drop of the H2 case is found to be higher than that obtained by assuming an H1 thermal boundary condition.

Automatic Removal of Imperfections and Change Detection for Accurate 3D Urban Cartography by Classification and Incremental Updating

In this article, we present a new method of automatic 3D urban cartography in which different imperfections are progressively removed by incremental updating, exploiting the concept of multiple passages, using specialized functions. In the proposed method, the 3D point clouds are first classified into three main object classes: permanently static, temporarily static and mobile, using a new point matching technique. The temporarily static and mobile objects are then removed from the 3D point clouds, leaving behind a perforated 3D point cloud of the urban scene. These perforated 3D point clouds obtained from successive passages (in the same place) on different days and at different times are then matched together to complete the 3D urban landscape. The changes occurring in the urban landscape over this period of time are detected and analyzed using cognitive functions of similarity, and the resulting 3D cartography is progressively modified accordingly. The specialized functions introduced help to remove the different imperfections, due to occlusions, misclassifications and different changes occurring in the environment over time, thus ncreasing the robustness of the method. The results, evaluated on real data, demonstrate that not only is the resulting 3D cartography accurate, containing only the exact permanent features free from imperfections, but the method is also suitable for handling large urban scenes.

Gaseous slip flow forced convection through ordered microcylinders

This is a theoretical study dealing with longitudinal gaseous slip flow forced convection between a periodic bunch of microcylinders arranged in regular array. The selected geometry has applications in microscale pin fin heat sinks used for cooling of microchips. The flow is considered to be hydrodynamically and thermally fully developed. The two axially constant heat flux boundary conditions of H1 and H2 are considered in the analysis. The velocity and temperature discontinuities at the boundary are incorporated into the solutions using the first order slip boundary conditions. The method considered is mainly analytical in which the governing equations and three of the boundary conditions are exactly satisfied. The remaining symmetry condition on the right-hand boundary of the typical element is applied to the solution through the point matching technique. The results show that both the Poiseuille number and the Nusselt number are decreasing functions of the degree of rarefaction characterized by the Knudsen number. While an increase in the blockage ratio leads to a higher Poiseuille number, the functionality of the Nusselt number on this parameter is not monotonic. At small and moderate values of the blockage ratio, the Nusselt number is higher for a higher blockage ratio, whereas the opposite may be right for higher values of this parameter. It is also observed that the angular variations of the parameters are reduced at smaller blockage ratios. Accordingly, the H1 and H2 Nusselt numbers are the same for small and moderate blockage ratios.

Analysis of multi-layer optical waveguides using a pseudospectral technique

A pseudospectral method is presented for the determination of propagation characteristicsin multi-layer optical waveguides. The method is based on transforming the Helmholtzeigenvalue equation from the spatial domain into the spectral domain and solving thetransformed equation in the spectral domain as an unbounded interval problem employinga point matching technique. Appropriate basis functions which take into account thephysical properties of the electromagnetic fields inside multi-layer optical waveguides areintroduced. Representing the constitutive relation with a convolution in the spectraldomain, we overcome the poor convergence problem of conventional pseudospectralmethods, which is due to abrupt changes in refractive-index profiles. The presented methodimplicitly includes all the boundary conditions of the problem. Its application to severalmulti-layer optical waveguides is demonstrated to verify the accuracy and efficiency of themethod. All the results are found to be in excellent agreement with those of analyticalsolutions.

Simulation of EM Scattering from 3-D Target by MOM with Pulse Basis Function

In this paper, electromagnetic (EM) scattering from a 3-D PEC target is simulated. The method of moments (MOM) with the pulse basis function and the point matching technique is presented to solve the magnetic field integral equation (MFIE). The flat triangular patch is applied to subdivide the surface of the 3-D target, and the surface unknowns are the arbitrary orthogonal unit vector of the triangular patch. Validity of this algorithm is shown by comparing the E plane and H plane radar cross section (RCS) from a sphere or a cylinder to those results of MOM with the RWG vector basis function. It is necessary to note that computational time of the algorithm presented in this paper is less than the MOM with the RWG(Rao Wilton Glisson) basis function.

Laminar Flow in Microchannels With Noncircular Cross Section

Analytical solutions are presented for laminar fully developed flow in micro-/minichannels of hyperelliptical and regular polygonal cross sections in the form of compact relationships. The considered geometries cover a wide range of common simply connected shapes including circle, ellipse, rectangle, rectangle-with-round-corners, rhombus, star-shape, equilateral triangle, square, pentagon, and hexagon. A point matching technique is used to calculate closed form solutions for the velocity distributions in the above-mentioned channel cross sections. The developed relationships for the velocity distribution and pressure drop are successfully compared with existing analytical solutions and experimental data collected from various sources for a variety of geometries, including polygonal, rectangular, circular, elliptical, and rhombic cross sections. The present compact solutions provide a convenient and power tool for performing hydrodynamic analyses in a variety of fundamental and engineering applications such as in microfluidics, transport phenomena, and porous media.

An Automatic and Robust Algorithm of Reestablishment of Digital Dental Occlusion

In the field of craniomaxillofacial (CMF) surgery, surgical planning can be performed on composite 3-D models that are generated by merging a computerized tomography scan with digital dental models. Digital dental models can be generated by scanning the surfaces of plaster dental models or dental impressions with a high-resolution laser scanner. During the planning process, one of the essential steps is to reestablish the dental occlusion. Unfortunately, this task is time-consuming and often inaccurate. This paper presents a new approach to automatically and efficiently reestablish dental occlusion. It includes two steps. The first step is to initially position the models based on dental curves and a point matching technique. The second step is to reposition the models to the final desired occlusion based on iterative surface-based minimum distance mapping with collision constraints. With linearization of rotation matrix, the alignment is modeled by solving quadratic programming. The simulation was completed on 12 sets of digital dental models. Two sets of dental models were partially edentulous, and another two sets have first premolar extractions for orthodontic treatment. Two validation methods were applied to the articulated models. The results show that using our method, the dental models can be successfully articulated with a small degree of deviations from the occlusion achieved with the gold-standard method.

Array of plasmonic particles enabling optical near-field concentration: A nonlinear inverse scattering design approach

The main idea of this paper is to design an array of core-shell plasmonic nanoparticles manipulating a desired near-field focusing pattern in optical spectrum. The interactions between the array elements are formulated by using dyadic Green's function analysis and by employing the closed-form formula for electric polarizability of each plasmonic particle (dipolar mode approach). The point-matching technique is applied to optimize the plasmonic-array field performance as close as to the desired near-field pattern. The final equation for finding the polarizability of each element will be a system of nonlinear equations that can be solved successfully by Levenberg-Marquardt technique. Controlling the inner and outer radii of each element using magnitude and phase contours of polarizability demonstrates a near-field subwavelength concentration. The accuracy of our theoretical model is successfully compared with a full-wave numerical analysis using CST commercial software. Interesting physical features for the optical near-field engineering are illustrated.

Analysis and Optimization of Wire Antennas over the Internet [EM Programmer's Notebook

With the recent deployment of wireless digital TV systems around the world, wire antennas are once again in widespread use. This article introduces the software GRADMAX for Web, a Java applet for analyzing and optimizing arrays of wire antennas. The analysis algorithm is based on the point-matching technique of the Method of Moments (MININEC engine), and the optimization layer employs the modified gradient method. GRADMAX for Web is designed for the Internet, and runs directly from the Web browser on all common operating systems (Windows, Macintosh, Linux, Solaris, etc.).