Rectilinear Projection Research Articles

Conformal Antenna Array Design Using Aperture Synthesis and On-Platform Modeling

Conformal antenna arrays have long represented an attractive solution to challenges imposed by an electromagnetic aperture on an aerospace platform. This allows designers to trade between array positioning and geometry, and avoids the significant aerodynamic drag of a planar array. This is hampered by the expense of the design and computational modelling required to ensure that a conformal array will meet its performance requirements. The proposed approach uses raycasting techniques to predict the rectilinear projection of a conformal aperture onto the farfield to calculate the maximum achievable beam coverage (aperture maximum directivity envelope). In order to compare aperture projection with the performance of the modelled arrays in a consistent manner, the steering efficiency (SE), which is the fraction of the farfield steerable to within 3dB of the maximum directivity, was calculated for the aperture, stacked patch, and conical monopole elements. The stacked patch elements demonstrated a SE of 18% over the steering plane compared with 40% for the arbitrary directional elements, and the optimum of 38% for the aperture overall. The Conical monopole elements achieved a SE of 8%, compared to 20% for the measured elements, and 33% achieved with arbitrary omnidirectional elements. These results demonstrate that, for both omnidirectional and directional elements, the aperture projection method offers a compelling tool for conformal array design, which is consistent with the achieved array performance for the stacked patch and conical monopole elements.

Objective Assessment of Perceived Geometric Distortions in Viewport Rendering of 360° Images

To render omnidirectional (or 360°) visual content, a projection that maps the pixels from a portion of the viewing sphere to a 2D plane must be employed; this projection creates the viewport image shown to the user and thus has an important role on the quality of experience, for this type of content. However, a sphere to planar projection always introduces geometrical distortions on the rendered image, such as stretching and/or bending of some image regions and structures, which may impact negatively the quality offered to the users. In this article, a content-aware objective quality metric, that predicts the perceived viewport quality, is proposed for the general perspective projection (GPP) rendering of 360° images, which includes the popular rectilinear and stereographic projections. The proposed metric relies on two set of features that characterize the bending of straight lines and stretching of image regions. The extracted features, and the corresponding viewport subjective quality CMOS (comparative mean opinion scores) are then used to build a quality prediction model, based on Support Vector Regression (SVR). The experimental results show that the proposed metric is able to predict the viewport CMOS with a Pearson correlation coefficient close to 0.8. Furthermore, it is shown that the proposed metric may be used to accurately find the GPP projection center that minimizes the perceived geometric distortions, according to the viewport content.

Artwork painting identification method for panorama based on adaptive rectilinear projection and optimized ASIFT

In the paper, the authors present an artwork painting identification method for panorama based on adaptive rectilinear projection and optimized ASIFT (Affine Scale-Invariant Feature Transform). Firstly, the authors use the panorama dataset to train the artwork painting detection network to obtain the location information of artwork paintings. Secondly, the authors use the adaptive rectilinear projection to map the artwork painting into a square image with a fixed size. Then the authors use the image enhancement method to improve the image quality. Finally, the authors use the optimized ASIFT for features extraction and image matching. Several contrast experiments were conducted on the artwork paintings panorama dataset for artwork paintings identification. The results show that the proposed method can achieve 96% identification accuracy on average for the whole test artwork paintings panorama dataset. The proposed adaptive rectilinear based-method can improve at least 20% of the recognition accuracy. The proposed optimized ASIFT can improve at least 30% of the identification accuracy than SIFT. The authors also study other factors such as the size of the original artwork image, the image matching threshold, whether using image enhancement or not. The results show the size of the original artwork has little influence on the artwork identification in the panorama. The image matching threshold with 2.0 is better than 3.0. Furthermore, using the image enhancement method can improve about 2% of the identification accuracy.

Distribution of University Admission Quotas: Problems of Competitive Selection Process

Introduction. Nowadays, an important criterion for the effectiveness of vocational education is the demand for graduates in the labour market. In order to ensure maximum compliance of the structure of training of specialists with the needs of the economy in personnel, the Ministry of Education and Science of theRussian Federation annually establishes admission quotas in universities on the basis of regional development forecasts. However, one of the options for the distribution of admission quotas in recent years has become an inter-university competition, as a result of which budget places are transferred to educational institutions only on the basisindicators of their effectiveness, i.e. excluding the dynamics of local labour markets. While the problems of coordination of admission quotas and the need for personnel are sufficiently covered in the literature, the mechanism of the distribution of places in the competition has been insufficiently studied so far.The aim of this research was to analyse the mechanism of competitive distribution of admission quotas on the example of higher education institutions, which provide training for bachelor and specialist programmes in the field of “Education and Pedagogical Sciences”.Methodology and research methods. The present research is based on the methodology of integrated research, including the methods of comparative and statistical analysis of data, their systematisation and generalisation.Results and scientific novelty. It is shown that the process of distribution of admission quotas is generated in accordance with the official competitive selection methodology. The study established that none of the indicators applied in the calculations of the effectiveness of universities’ activities were statistically related to the results of the competition. The main reason for the inability of the competitive mechanism to carry out the correct ranking of participants in terms of success is the major methodological and mathematical errors inherent in the algorithms for determining the effectiveness of educational organisations. As a result, the number of budget places allocated to each university is largely determined by chance. The results of the competitive distribution of admission quotas depend only on the industry sector of educational institutions. The widespread development of the idea of quoting of budgetary education on indicators of an interuniversity competition will inevitably aggravate a disproportion problem between territorial training and demand for them in regions. There will certainly be a deficiency of young specialists due to low mobility of graduates of the Russian higher school and reduction of the contingent of provincial higher education institutions-outsiders. Conversely, the personnel surplus will appear in the regional educational institutions (mainly metropolitan), which won the competitions. The proposals on correction of the evolving negative socio-economic situation are formulated.Practical significance. The authors believe that the research results will make it possible to thoroughly discuss the rectilinear projection of effective outcome monitoring in higher education institutions for competitive distribution of admission quotas and the feasibility of holding a competition in general. Moreover, the results of the present study contribute to the method of competitive distribution of university admission quotas.

Circular Calibration of Depth Extraction in Stereo Configuration

Lens distortion is defined as departure from rectilinear projection of an imaging system which affects the accuracy of almost all vision applications. This work addresses the problem of distortion with investigating the effects of camera’s view angle and spherical nature of lens on image, and then derives a closed-form solution for the correction of distorted pixel's angle in image according to geometric shape of lens. We first propose technique that explores the linear relation between lens and charge-coupled device in intrinsic environment of camera, through analysis of pixel’s angle in field of view. Second technique for depth extraction through linear transformation in rectangular configuration is achieved by considering the camera’s background in field of view which provides optimal results in closed environment. As the object moves away from the center of image in image plane, depth accuracy starts to deteriorate due to radial distortion. To rectify this problem, we finally purpose circular calibration methodology which addresses this inaccuracy and accommodate radial distortion to achieve optimal results up to 98%, in great depth with very large baseline. Results show the improvement over established stereo imaging techniques in depth extraction where the presented considerations are not observed. This methodology ensures high accuracy of triangulated depth with very large base line.

Artwork Identification for 360-Degree Panoramic Images Using Polyhedron-Based Rectilinear Projection and Keypoint Shapes

With the increased development of 360-degree production technologies, artwork has recently been photographed without authorization. To prevent this infringement, we propose an artwork identification methodology for 360-degree images. We transform the 360-degree image into a three-dimensional sphere and wrap it with a polyhedron. On the sphere, several points are located on the polyhedron to determine the width, height, and direction of the rectilinear projection. The 360-degree image is divided and transformed into several rectilinear projected images to reduce the adverse effects from the distorted panoramic image. We also propose a method for improving the identification precision of artwork located at a highly distorted position using the difference of keypoint shapes. After applying the proposed methods, identification precision is increased by 45% for artwork that is displayed on a 79-inch monitor in a seriously distorted position with features that were generated by scale-invariant feature transformations.

QRPC: A new qualitative model for representing motion patterns

The Qualitative Rectilinear Projection Calculus (QRPC), a new representation model based on planar trajectories, is presented in this work for describing qualitatively motion patterns. Several models have been developed for this purpose and by comparing them with our proposal we show that the proposed model results in an intuitive approach for representing, in any context, the kinematical behavior of two objects in motion on the plane through the possible relationships among the rectilinear projection of their trajectories. The paper is centered on the formal definition of the set of geometric relations in terms of the front–back and left–right dichotomies, and how by the composition of these relations, it can be possible enumerate an exhaustive set of qualitative states and the possible transitions among them. The complete iconic representation of the set of qualitative states defines the Conceptual Neighborhood Graph of the QRPC model. In order to illustrate how this qualitative representation can be used to analyze and describe the relative motion of two objects, some examples extracted from the traffic engineering field have been studied.

Modeling orthogonal and rectilinear mixed-modality projection of optical tomography for solid-particles concentration measurement

In optical tomography, light attenuation/scattering methods have been used to determine average solids concentrations in gas-solids flows. Derived from the Lambert–Beer law, the Mie theory forms the theoretical basis for optical sensor. It states that the intensity of light transmitted through a dilute gas–solids mixture should be exponentially related to the solids concentration in the light beam. In this context, the light transmits continuously and any particle passing though the volume interrogated by a sensor is detected as variation in the level of illumination of the sensor. This paper focused the modeling for a novel mixed-modality of orthogonal and rectilinear projections. A novel image reconstruction algorithm has been applied and also tested on the modeling.

Embedded system based optical tomography: the concentration profile

PurposeThe purpose of this paper is to view the flow concentration of the flowing material in a pipeline conveyor.Design/methodology/approachOptical tomography provides a method to view the cross sectional image of flowing materials in a pipeline conveyor. Important flow information such as flow concentration profile, flow velocity and mass flow rate can be obtained without the need to invade the process vessel. The utilization of powerful computer together with expensive data acquisition system (DAQ) as the processing device in optical tomography systems has always been a norm. However, the advancements in silicon fabrication technology nowadays allow the fabrication of powerful digital signal processors (DSP) at reasonable cost. This allows the technology to be applied in optical tomography system to reduce or even eliminate the need of personal computer and the DAQ. The DSP system was customized to control the data acquisition of 16 × 16 optical sensors (arranged in orthogonal projection) and 23 × 23 optical sensors (arranged in rectilinear projections). The data collected were used to reconstruct the cross sectional image of flowing materials inside the pipeline. In the developed system, the accuracy of the image reconstruction was increased by 12.5 per cent by using new hybrid image reconstruction algorithm.FindingsThe results proved that the data acquisition and image reconstruction algorithm is capable of acquiring accurate data to reconstruct cross sectional images with only little error compared to the expected measurements.Originality/valueThe DSP system was customized to control the data acquisition of 16 × 16 optical sensors (arranged in orthogonal projection) and 23 × 23 optical sensors (arranged in rectilinear projections).

Chemical reaction surface vibrational frequencies evaluated in curvilinear internal coordinates: Application to H+CH4⇌H2+CH3

We consider the general problem of vibrational analysis at nonglobally optimized points on a reduced dimensional reaction surface. We discuss the importance of the use of curvilinear internal coordinates to describe molecular motion and derive a curvilinear projection operator to remove the contribution of nonzero gradients from the Hessian matrix. Our projection scheme is tested in the context of a two-dimensional quantum scattering calculation for the reaction H + CH(4) --> H(2) + CH(3) and its reverse H(2) + CH(3) --> H + CH(4). Using zero-point energies calculated via rectilinear and curvilinear projections we construct two two-dimensional, adiabatically corrected, ab initio reaction surfaces for this system. It is shown that the use of curvilinear coordinates removes unphysical imaginary frequencies observed with rectilinear projection and leads to significantly improved thermal rate constants for both the forward and reverse reactions.

Optical Tomography System: Digital Sensors for Masking Purpose in Parallel Beam Optical Tomography System

Due to the lack of the number of projections available in a Parallel Beam Optical Tomography System (only x-axis and y-axis, also known as orthogonal projection), ambiguous image will be constructed when the flowing materials fall into certain positions in the pipeline. Therefore, two rectilinear projections are added to the system in order to correct this ambiguous image. However, the rectilinear projection only acts as a mask. Thus, converting the analog signals from the rectilinear sensors into binary digital signals is already sufficient.

Wide-angle catadioptric lens with a rectilinear projection scheme

A catadioptric wide-angle lens having a rectilinear projection scheme has been developed with a view to possible applications in the security-surveillance area. The lens has been designed for a miniature camera with a video graphics array-grade 1/3 in. color CCD sensor. The field of view of the lens is over 151 degrees , and still distortion is under 1%. Furthermore, the modulation transfer function is better than 0.3 at 70 line pairs/mm over the whole active area of the image sensor.

Design of a Mega-pixel Grade Catadioptric Panoramic Lens with the Rectilinear Projection Scheme

A dedicated catadioptric panoramic lens with the rectilinear projection scheme is designed. The resolution is high enough to provide separate VGA quality images for the respective four directions and the image distortion is less than 0.5%.

Optical tomography sensor configuration using two orthogonal and two rectilinear projection arrays

This paper represents the configuration of an optical tomography sensor by using infrared emitters and phototransistors. The projection geometry of the sensor is based on the combination of two orthogonal and two rectilinear projection arrays. A fixture is designed for holding all emitter–receiver pairs in parallel. Selection of the phototransistor is explained so that the tomography sensor developed is free of noise caused by the surrounding environment. This paper describes all points to be considered when designing an optical tomography sensor. The results show that the developed system has the capability to detect the concentration profile of the flow.

Real-time image reconstruction for various flow regimes using an optical tomography sensor in a gravity flow conveyor

Abstract The aim of this project is monitoring real-time flow imaging when various baffles are created to block certain areas of a pipe so that flowing particles can be controlled using difference patterns with the same flow rate. The generated flow regimes are full flow, three-quarter flow, half flow and quarter flow. A vertical pneumatic conveyor is designed for holding a 85-mm inner diameter pipeline. The corresponding optical tomography sensor uses a parallel beam projection approach with an IR light source so that the sensor is free of noise from any surrounding visible light source. The two orthogonal projections and two rectilinear projections are ideally in the same layer. The sensor readings provide cross-sectional distribution information in the conveyor. It can be related to the varying light intensity affected by the dropping particles. By using computer programming, the information will be reconstructed to form an image by referring to a color intensity bar. The results obtained from this project show that flow imaging follows the artificial flow regime. It will beneficial in the industrial production line to maintain the flow rate.