Coordinate Interpolation Research Articles

Extracting focus variation data from coherence scanning interferometric measurements

Coherence scanning interferometry (CSI), based on the principle of interference, can achieve sub-nanometer precision for height measurements. On the other hand, focus variation microscopy (FVM), combining the small depth of field of the objective, is a widely used surface topography measurement method suited to surface topography that is mostly optically rough. In this paper, we propose a method to simultaneously obtain the interferometric fringe data and focus variation FVM image stack, from a single vertical scanning process, using a CSI instrument without any hardware modifications. Using a 3D Fourier transform, the FVM signal, looks takes the form of a “bowtie” and the CSI signal resembles two “umbrellas” that are separated in 3D K-space. The signal is recovered using a 3D inverse Fourier transform and the surface topography can be determined by fusing the CSI and FVM signals. Since both signals come from the same instrument and scanning process, there is no need for coordinate registration and data interpolation during the data fusion process. Our method combines the features of CSI and FVM measurement, thereby improving the robustness and data coverage of the measurement. An all-in-focus surface topography map can also be generated using this method. This focusing feature has the potential to significantly improve the defect detection and quality control ability of CSI instruments.

Direct distortion prediction method for AR-HUD dynamic distortion correction.

Dynamic distortion is one of the most critical factors affecting the experience of automotive augmented reality head-up displays (AR-HUDs). A wide range of views and the extensive display area result in extraordinarily complex distortions. Existing methods based on the neural network first obtain distorted images and then get the predistorted data for training mostly. This paper proposes a distortion prediction framework based on the neural network. It directly trains the network with the distorted data, realizing dynamic adaptation for AR-HUD distortion correction and avoiding errors in coordinate interpolation. Additionally, we predict the distortion offsets instead of the distortion coordinates and present a field of view (FOV)-weighted loss function based on the spatial-variance characteristic to further improve the prediction accuracy of distortion. Experiments show that our methods improve the prediction accuracy of AR-HUD dynamic distortion without increasing the network complexity or data processing overhead.

Excited State Dynamics of Dibenzothiophene Derivatives.

Polycyclic aromatic sulfur heterocycles are environmental pollutants formed from incomplete combustion processes and crude oil spills. Their excited state dynamics are not understood. Herein, femtosecond transient absorption is combined with steady-state spectroscopy and computational methods to elucidate the relaxation mechanisms of three dibenzothiophene derivatives. The low-energy singlet and triplet states all have ππ* character in the Franck-Condon region, and two minima were located in the S1 surface. Excitation at 320 nm populates their S1 state directly, which relaxes with lifetimes ranging from 4 to 13 ps. Most of the S1 population undergoes efficient intersystem crossing to the triplet state with lifetimes ranging from 820 ± 50 to 900 ± 30 ps. The compounds exhibit negligible nonradiative internal conversion, low fluorescence yields of 1.2 to 1.6%, and triplet yields of ca. 98%. Linear interpolation of internal coordinates reveals the chemical basis for relaxing the spin-forbidden intersystem crossing in these π-aromatic systems.

Tackling Hysteresis in Conformational Sampling: How to Be Forgetful with MEMENTO.

The structure of proteins has long been recognized to hold the key to understanding and engineering their function, and rapid advances in structural biology and protein structure prediction are now supplying researchers with an ever-increasing wealth of structural information. Most of the time, however, structures can only be determined in free energy minima, one at a time. While conformational flexibility may thus be inferred from static end-state structures, their interconversion mechanisms─a central ambition of structural biology─are often beyond the scope of direct experimentation. Given the dynamical nature of the processes in question, many studies have attempted to explore conformational transitions using molecular dynamics (MD). However, ensuring proper convergence and reversibility in the predicted transitions is extremely challenging. In particular, a commonly used technique to map out a path from a starting to a target conformation called steered MD (SMD) can suffer from starting-state dependence (hysteresis) when combined with techniques such as umbrella sampling (US) to compute the free energy profile of a transition. Here, we study this problem in detail on conformational changes of increasing complexity. We also present a new, history-independent approach that we term "MEMENTO" (Morphing End states by Modelling Ensembles with iNdependent TOpologies) to generate paths that alleviate hysteresis in the construction of conformational free energy profiles. MEMENTO utilizes template-based structure modelling to restore physically reasonable protein conformations based on coordinate interpolation (morphing) as an ensemble of plausible intermediates, from which a smooth path is picked. We compare SMD and MEMENTO on well-characterized test cases (the toy peptide deca-alanine and the enzyme adenylate kinase) before discussing its use in more complicated systems (the kinase P38α and the bacterial leucine transporter LeuT). Our work shows that for all but the simplest systems SMD paths should not in general be used to seed umbrella sampling or related techniques, unless the paths are validated by consistent results from biased runs in opposite directions. MEMENTO, on the other hand, performs well as a flexible tool to generate intermediate structures for umbrella sampling. We also demonstrate that extended end-state sampling combined with MEMENTO can aid the discovery of collective variables on a case-by-case basis.

Exploring conformational transitions in membrane proteins with memento.

Despite rapid advances in cryo-EM delivering structures of membrane transport proteins at an unprecedented rate, they are typically solved in one conformational state. Whilst conformational flexibility can be inferred from static end-state structures, the interconversion mechanisms between states are often beyond the scope of direct experimentation. Given the dynamical nature of the processes in question, many studies have attempted to explore conformational transitions using molecular dynamics. However, ensuring proper convergence and reversibility in the predicted transitions is extremely challenging. In this work, we present an approach that we term “MEMENTO” (morphing end states by modelling ensembles with independent Topologies) to generate paths that alleviate starting state dependence (hysteresis) in the construction of conformational free energy profiles. MEMENTO utilises template-based structure modelling to restore physically reasonable protein conformations based on coordinate interpolation (morphing), and we apply it in conjunction with replica-exchange umbrella sampling to sample likely transitions. We demonstrate how the method works via application to well-characterized test cases (deca-alanine and adenylate kinase) before discussing its use in transporter proteins. We also suggest that extended end-state sampling combined with MEMENTO can aid the discovery of collective variables for umbrella sampling on a case-by-case basis.

A full-flow inspection method based on machine vision to detect wafer surface defects.

The semiconductor manufacturing industry relies heavily on wafer surface defect detection for yield enhancement. Machine learning and digital image processing technologies have been used in the development of various detection algorithms. However, most wafer surface inspection algorithms are not be applied in industrial environments due to the difficulty in obtaining training samples, high computational requirements, and poor generalization. In order to overcome these difficulties, this paper introduces a full-flow inspection method based on machine vision to detect wafer surface defects. Starting with the die image segmentation stage, where a die segmentation algorithm based on candidate frame fitting and coordinate interpolation is proposed for die sample missing matching segmentation. The method can segment all the dies in the wafer, avoiding the problem of missing dies splitting. After that, in the defect detection stage, we propose a die defect anomaly detection method based on defect feature clustering by region, which can reduce the impact of noise in other regions when extracting defect features in a single region. The experiments show that the proposed inspection method can precisely position and segment die images, and find defective dies with an accuracy of more than 97%. The defect detection method proposed in this paper can be applied to inspect wafer manufacturing.

Accurate TCP Position and Orientation Trajectory Generation in 6DOF Robotic Manipulators and CNC Machine Tools using FIR Filtering and Haversine Synchronisation

The use of robotics in manufacturing is rapidly growing. One promising application in particular is the use of robots as machining platforms. Robotic machining offers many advantages such as large operating envelopes, flexibility in operations and low installation and running costs. Robotic machining platforms much like computer numerically controlled (CNC) machine tools are commanded by numerical controllers (NCs) using the well established G-code part programming language (ISO-6983). Toolpaths are defined in the work piece coordinate system (WCS) as a series of discrete tool centre point (TCP) positions and tool orientations. The role of the NC is to generate smooth feed drive or robot joint commands such that the tool or end effector travels along the commanded toolpath whilst satisfying TCP position and orientation tolerances and robot/machine tool kinematic constraints. Interpolating tool orientations directly in the WCS requires complex real-time spherical interpolation computations. Overcoming this challenge, this paper introduces a C4 continuous tool path trajectory generation method for 6DOF motion. The tool centre point position is smoothed in the WCS, however, the tool orientation is smoothed directly in the rotary coordinate system without the requirement for spherical interpolation. The interpolated tool orientation trajectory follows the path of the great circle arc using the modified Haversine method eliminating non-linear interpolation errors present in linear interpolation of rotary axis positions (machine coordinate system interpolation). The proposed method is validated by simulation of a 6DOF robotic manipulator.

Linear barycentric rational collocation method to solve plane elasticity problems.

A linear barycentric rational collocation method for equilibrium equations with polar coordinates is considered. The discrete linear equations is changed into the matrix forms. With the help of error of barycentrix polar coordinate interpolation, the convergence rate of the linear barycentric rational collocation method for equilibrium equations can be obtained. At last, some numerical examples are given to valid the proposed theorem.

A Variational Interpolation Method for Gridding Weather Radar Data

Abstract Observations made by weather radars play a central role in many aspects of meteorological research and forecasting. These applications commonly require that radar data be supplied on a Cartesian grid, necessitating a coordinate transformation and interpolation from the radar’s native spherical geometry using a process known as gridding. In this study, we introduce a variational gridding method and, through a series of theoretical and real data experiments, show that it outperforms existing methods in terms of data resolution, noise filtering, spatial continuity, and more. Known problems with existing gridding methods (Cressman weighted average and nearest neighbor/linear interpolation) are also underscored, suggesting the potential for substantial improvements in many applications involving gridded radar data, including operational forecasting, hydrological retrievals, and three-dimensional wind retrievals.

Physics-Based Simulation of Soft-Body Deformation Using RGB-D Data.

Providing real-time interaction in an immersive environment has drawn considerable attention in the virtual training fields. Physics-based simulations are suitable for such environments; however, they require the definition and adjustment of coefficients that determine material properties, making the methods more complex and time-consuming. In this paper, we introduce a novel approach to simulating the soft-body deformation of an observed object. Using an off-the-shelf RGB-D sensor, the proposed approach tracks an object’s movement and simulates its deformation in an iterative manner. Polygonal models with different resolutions are used to improve the simulation speed and visual quality. During the simulation process, a low-resolution model is used for surface deformation using neighboring feature points detected from the sensor, and a volumetric model is added for internal force estimation. To visualize the observed model in detail, the deformed and low-resolution model is mapped to a high-resolution model using mean value coordinate interpolation. To handle topological deformations, such as cutting or tearing, a part intersected by a cutting tool is recognized by the sensor and responds to external forces. As shown in the experimental results, our approach generates convincing deformations of observed objects in real time.

Efficient Massive Computing for Deformable Volume Data Using Revised Parallel Resampling

In this paper, we propose an improved parallel resampling technique. Parallel resampling is a deformable object generation method based on volume data applied to medical simulations. Existing parallel resampling is not suitable for massive computing, because the number of samplings is high and floating-point precision problems may occur. This study addresses these problems to obtain improved user latency when performing medical simulations. Specifically, instead of interpolating values after volume sampling, the efficiency is improved by performing volume sampling after coordinate interpolation. Next, the floating-point error in the calculation of the sampling position is described, and the advantage of barycentric interpolation using a reference point is discussed. The experimental results showed a significant improvement over the existing method. Volume data comprising more than 600 images used in clinical practice were deformed and rendered at interactive speed. In an Internet of Everything environment, medical imaging systems are an important application, and simulation image generation is also valuable in the overall system. Through the proposed method, the performance of the whole system can be improved.

Analysis of the Application Prospect of Computer Image Processing Technology in UI Design

In order to improve the interface experience effect of the mobile terminal software, this paper improves the UI design by combining computer image processing technology and improves the diffusion algorithm for images by improving the diffusion model, improving the diffusion coefficient and adaptively selecting the diffusion threshold. Moreover, this paper has carried out deep research on coordinate transformation and image interpolation and stored the result of coordinate transformation in the coordinate transformation table and weight table. In addition, this paper proposes an improved digital scan conversion method based on a lookup table and constructs an improved UI design system model. Through the analysis of experimental data, it can be seen that the application effect of computer image processing technology in UI design is very good, and it can effectively promote the improvement of UI design technology.

Application of Digital Image Processing Technology in the Remote Interactive Art Teaching System

Modern distance teaching activities have occupied an important position in current education and teaching activities. This research mainly discusses the application of digital image processing technology in remote interactive art teaching systems. In order to avoid complicated calculation and a huge amount of calculation, reduce the difficulty of calculation, and improve the correction speed of distorted image and for qualitative recognition and correction of a large background and small target (or medium and small target) digital images (video is regarded as a special form of continuous image, method-like) that appear in a large number of remote teaching activities, this paper proposes a direct look-up method based on coordinate interpolation, that is, to establish the approximate correspondence between the image coordinate positions before and after the distortion and build a reference model for comparing the two image coordinates through experimental data. The system design includes overall design, functional module design, and database design. To realize the function of distance education, it must have characteristics different from ordinary networks and the most important thing is that its transmission bandwidth should be large. Because the distance education platform needs to be able to transmit the teaching text, hear the teacher’s voice, see the teacher’s teaching image content, and even see the carefully designed animation, the distance education system must have a very wide bandwidth. The database tables are designed using entity attribute diagrams and E-R diagrams. E-R diagram is also called entity-connection diagram, which provides a way to express entity types, attributes, and connections. It is used to describe the conceptual model of the real world. Remote online test management includes test content perform operations such as addition. The art teaching management system designed in the article will make teachers and students no longer be restricted by time and place and can inquire about students’ information, choose courses freely, inquire about grades, and understand the teaching plan anytime and anywhere. This research helps to promote the development of remote interactive technology.

Five-Axis Trajectory Generation Considering Synchronization and Nonlinear Interpolation Errors

Abstract This paper presents a novel real-time interpolation technique for five-axis machine tools to attain higher speed and accuracy. To realize computationally efficient real-time interpolation of 6-DOF tool motion, a joint workpiece–machine coordinate system interpolation scheme is proposed. Cartesian motion of the tool center point (TCP) is interpolated in the workpiece coordinate system (WCS), whereas tool orientation is interpolated in the machine coordinate system (MCS) based on the finite impulse response filtering. Such an approach provides several advantages: (i) it eliminates the need for complex real-time spherical interpolation techniques, (ii) facilitates efficient use of slower rotary drive kinematics to compensate for the dynamic mismatch between Cartesian and rotary axes and achieve higher tool acceleration, and (iii) mitigates feed fluctuations while interpolating near kinematic singularities. To take advantage of such benefits and realize accurate joint WCS–MCS interpolation scheme, tool orientation interpolation errors are analyzed. A novel approach is developed to adaptively discretize long linear tool moves and confine interpolation errors within user set tolerances. Synchronization errors between TCP and tool orientation are also characterized, and peak synchronization error level is determined to guide the interpolation parameter selection. Finally, blending errors during non-stop continuous interpolation of linear toolpaths are modeled and confined. Advantages of the proposed interpolation scheme are demonstrated through simulation studies and validated experimentally. Overall, proposed technique can improve cycle times up to 10% while providing smooth and accurate non-stop real-time interpolation of tool motion in five-axis machining.

Shape congruence modulates visuo-haptic interactions during binocular rivalry

When two dissimilar images are presented to the corresponding retinal positions of the two eyes, perception alternates between the two images (Blake & Logothetis, 2002). Dubbed binocular rivalry (BR), this paradigm provides a window into inferential visual processing. Recent experiments using multisensory stimuli found that tactile information boosts the dominance of the congruent visual stimulus (Lunghi et al., 2010; Suzuki et al., 2019). The present study examines whether dynamic haptic exploration of 3D shape objects boosts the perception of congruent visual shape stimuli during BR. 3D spiky and round shapes were created with a parametric shape model (Gielis, 2003). The coordinates for the neutral shape were acquired through linear interpolation of round and spiky shape coordinates (Kwak et al., VSS 2018). Visual and haptic stimuli were each created by 3D rendering and 3D printing the shape models. Participants viewed a pair of rotating round and spiky shapes as rival targets while exploring haptic objects with their left hand. They used their right hand to track perceptual dominance via computer key press. There were four haptic conditions - three exploring round, spiky, and neutral shape objects and one with no haptic stimulation (visual-only). Visual dominance durations for each condition were normalized with the mean duration of visual-only trials to account for individual differences. Analyses showed significant differences in the normalized dominance durations of both round and spiky visual targets when exploring haptic stimuli of different shapes. Specifically, haptic exploration of an object was associated with increased dominance of the corresponding visual target for both round and spiky shape during BR. With these results based on stimuli parametrically modulated in a single shape dimension of curvature, we suggest that shape congruence between visual and haptic modalities boosts the dominance of the corresponding visual target.

Approach for ISAR imaging of near-field targets based on coordinate conversion and image interpolation

Inverse synthetic aperture radar (ISAR) imaging of near-field targets is potentially useful in some specific applications, which makes it very important to efficiently produce high-quality image of the near-field target. In this paper, the simplified target model with uniform linear motion is applied to the near-field target imaging, which overcomes the complexity of the traditional near-field imaging algorithm. According to this signal model, the method based on coordinate conversion and image interpolation combined with the range-Doppler (R-D) algorithm is proposed to correct the near-field distortion problem. Compared with the back-projection (BP) algorithm, the proposed method produces better focused ISAR images of the near-field target, and decreases the computation complexity significantly. Experimental results of the simulated data have demonstrated the effectiveness and robustness of the proposed method.

Simulation of the Ronchi test for arbitrary wave aberrations in imaging systems

The Ronchi test is a simple qualitative method to identify aberrations in imaging systems: a binary grating is superimposed on its own image formed by the system to produce patterns, known as Ronchigrams, that manifest the aberrations in the system. In practice, the experimentally recorded Ronchigrams are compared with model-based simulations to infer the types and amounts of wave aberrations. In this article an effective algorithm to simulate the Ronchigrams in an imaging system under arbitrary third-order wave aberrations is introduced. The method uses simple coordinate interpolation to transfer the grating transmittance from the object to the image space. High-quality Ronchigrams for all types of wave aberrations can easily be produced. For demonstration purposes, experimental Ronchigrams obtained in real imaging systems are also provided and compared with the simulations. The results show that this technique can both be used as an educational tool, and also in a real test setup.

UniFaceGAN: A Unified Framework for Temporally Consistent Facial Video Editing.

Recent research has witnessed advances in facial image editing tasks including face swapping and face reenactment. However, these methods are confined to dealing with one specific task at a time. In addition, for video facial editing, previous methods either simply apply transformations frame by frame or utilize multiple frames in a concatenated or iterative fashion, which leads to noticeable visual flickers. In this paper, we propose a unified temporally consistent facial video editing framework termed UniFaceGAN. Based on a 3D reconstruction model and a simple yet efficient dynamic training sample selection mechanism, our framework is designed to handle face swapping and face reenactment simultaneously. To enforce the temporal consistency, a novel 3D temporal loss constraint is introduced based on the barycentric coordinate interpolation. Besides, we propose a region-aware conditional normalization layer to replace the traditional AdaIN or SPADE to synthesize more context-harmonious results. Compared with the state-of-the-art facial image editing methods, our framework generates video portraits that are more photo-realistic and temporally smooth.

Parallel multi-view polygon rasterization for 3D light field display.

Three-dimensional (3D) light field displays require samples of image data captured from a large number of regularly spaced camera images to produce a 3D image. Generally, it is inefficient to generate these images sequentially because a large number of rendering operations are repeated in different viewpoints. The current 3D image generation algorithm with traditional single viewpoint computer graphics techniques is not sufficiently well suited to the task of generating images for the light field displays. A highly parallel multi-view polygon rasterization (PMR) algorithm for 3D multi-view image generation is presented. Based on the coherence of the triangular rasterization calculation among different viewpoints, the related rasterization algorithms including primitive setup, plane function, and barycentric coordinate interpolation in the screen space are derived. To verify the proposed algorithm, a hierarchical soft rendering pipeline with GPU is designed and implemented. Several groups of images of 3D objects are used to verify the performance of the PMR method, and the correct 3D light field image can be achieved in real time.

A Mutual-Capacitance 3-D Gesture Sensing System Based on 2-D Orthogonal Encoding and an Un-Folding Coordinate Interpolation Schemes

This paper describes the design of a capacitance readout IC for 3-D hover gesture sensing system. The proposed IC adopts a multi-channel driving scheme in both driving and sensing electrodes of a TSP (touch screen panel). The proposed single encoding and summing (ENS) filter in the readout circuit senses all TSP channels at once, thereby reducing the power consumption and chip area. An incorporated correlated double sampler (CDS) performs down-conversion of the capacitance signal and moving average filtering for severe noise interferences with high pass-filtering of the ENS filter. The proposed IC also employs an efficient hovering gesture detection method that is based on an un-folding 1-dimensional coordinate extraction scheme and various triggering events. By employing the cascade driving for hovering detection, the hover frame rate is maintained to be the same as the TSP frame rate while achieving a targeted signal-to-noise ratio (SNR). The proposed readout IC was fabricated on a 130-nm CMOS process. The IC achieves 26-dB SNR at 10-mm hover height and 120-Hz frame rate with $16\times16$ TSP. The front end circuit occupies a chip area of 0.0912-mm2 and supports a supply voltage ranging from 2.7 V to 3.3 V.