Representation Of Three-dimensional Objects Research Articles

Single-Shot 3D Reconstruction via Nonlinear Fringe Transformation: Supervised and Unsupervised Learning Approaches.

The field of computer vision has been focusing on achieving accurate three-dimensional (3D) object representations from a single two-dimensional (2D) image through deep artificial neural networks. Recent advancements in 3D shape reconstruction techniques that combine structured light and deep learning show promise in acquiring high-quality geometric information about object surfaces. This paper introduces a new single-shot 3D shape reconstruction method that uses a nonlinear fringe transformation approach through both supervised and unsupervised learning networks. In this method, a deep learning network learns to convert a grayscale fringe input into multiple phase-shifted fringe outputs with different frequencies, which act as an intermediate result for the subsequent 3D reconstruction process using the structured-light fringe projection profilometry technique. Experiments have been conducted to validate the practicality and robustness of the proposed technique. The experimental results demonstrate that the unsupervised learning approach using a deep convolutional generative adversarial network (DCGAN) is superior to the supervised learning approach using UNet in image-to-image generation. The proposed technique's ability to accurately reconstruct 3D shapes of objects using only a single fringe image opens up vast opportunities for its application across diverse real-world scenarios.

IMMERSIVE TECHNOLOGIES AND THEIR IMPACT ON THE MODERNIZATION OF THE MODERN EDUCATION SYSTEM

The use of immersive technologies opens up many prospects for improving the quality of the educational process. According to scientific studies, immersive technologies improve students' spatial understanding and memorization, allowing them to experience learning from the first person, to see everything that is happening around them. Such technologies provide visual learning and contribute to students' overall understanding of more complex subjects, theories and languages. Some researchers single out several unique possibilities of virtual and augmented reality, namely immersion in a simulated environment, multimodal interaction, concretization of imagination. In general, according to most researchers, these technologies ensure the presence of users due to the high accuracy of the representation of three-dimensional virtual objects and the ability to simulate operations and procedures of abstract concepts. Currently, the Ukrainian education system is taking only the first steps in the direction of using immersive technologies. A fairly small number of Ukrainian educators have started using them in the educational process. Accordingly, the problems and prospects of introducing virtual and augmented reality technology into the educational process of Ukrainian educational institutions have not been sufficiently researched. This publication analyzes the impact of immersive technologies on the modernization of the modern education system. The essence of immersive technologies and their impact on the transformation of learning processes is revealed. Identified types of immersive technologies. The main problems of introducing immersive technologies into the educational environment of Ukrainian educational institutions are analyzed. The results of a sociological study, the purpose of which was to study the public opinion of teachers regarding the assessment of the impact of immersive technologies on the educational environment, identify problems and features of the introduction of these technologies into the modern education system, are presented. According to the results of a sociological study, the most common foreign and domestic AR and VR applications, which are used by teachers in general secondary education institutions and contribute to the effectiveness of learning processes, have been determined. The main trends of the further implementation of immersive learning in the modern education system of Ukraine are considered.

UAS IR-Thermograms Processing and Photogrammetry of Thermal Images for the Inspection of Building Envelopes

Infrared thermography techniques (IRT) are increasingly being applied in non-invasive structural defect detection and building inspection, as they provide accurate surface temperature (ST) and ST contrast (Delta-T) information. The common optional or off-the-shelf installation, of both low- and high-resolution thermal cameras, on commercial UAS further facilitates the application of IRT by enabling aerial imaging for building envelope surveys. The software used in photogrammetry is currently accurate and easy to use. The increasing computational capacity of the hardware allows three-dimensional models to be obtained from conventional photography, thermal, or even multispectral imagery with very short processing times, further improving the possibilities of analysing buildings and structures. Therefore, in this study, which is an extension of a previous work, the analysis of the envelope of a wine cellar, using manual thermal cameras, as well as cameras installed on board an Unmanned Aerial System (UAS), will be presented. Since the resolution of thermal images is much lower than that of conventional photography, and their nature does not allow for accurate representation of three-dimensional objects, a new, but simple, digital image pre-processing method will be presented to provide a more detailed 3D model. Then, the three-dimensional reconstruction, based on thermal imagery, of the building envelope will be performed and analysed. The limitations of each technique will be also detailed, together with the anomalies found and the proposed improvements.

Plenoptic Point Cloud Compression Using Multiview Extension of High Efficiency Video Coding

Plenoptic point clouds are more complete representations of three-dimensional (3-D) objects than single-color point clouds, as they can have multiple colors per spatial point, representing colors of each point as seen from different view angles. They are more realistic but also involve a larger volume of data in need of compression. Therefore, in this paper, a multiview-video-based framework is proposed to better exploit correlations in color across different viewpoints. To the best of the authors' knowledge, this is the first work to exploit correlations in color across different viewpoints using a multiview-video-based framework. In addition, it is observed that some unoccupied pixels, which do not have corresponding points in plenoptic point clouds and are of no use to the quality of the reconstructed plenoptic point cloud colors, may cost many bits. To address this problem, a block-based group smoothing and a combined occupancy-map-based rate distortion optimization and four-neighbor average residual padding are further proposed to reduce the bit cost of unoccupied color pixels. The proposed algorithms are implemented in the moving pictures experts group (MPEG) video-based point cloud compression (V-PCC) and multiview extension of High Efficiency Video Coding (MV-HEVC) reference software. The experimental results show that the proposed algorithms can lead to a Bjontegaard Delta bitrate (BD-rate) reduction of 40% compared with the RAHT-KLT. Compared with the V-PCC independently applied to each view direction, the proposed algorithms can provide a BD-rate reduction of over 70%.

Interpolation graph convolutional network for 3D point cloud analysis

The feature analysis of point clouds, a popular representation of three-dimensional (3D) objects, is rising as a hot research topic nowadays. Point cloud data bear a sparse and unordered nature, making many commonly used feature extraction methods, for example, Convolutional Neural Networks (CNNs) inapplicable, while previous models suitable for the task are usually complex. We aim to reduce model complexity by reducing the number of parameters while achieving better (or at least comparable) performance. We propose an Interpolation Graph Convolutional Network (IGCN) for extracting features of point clouds. IGCN uses the point cloud graph structure and a specially designed Interpolation Convolution Kernel to mimic the operations of CNN for feature extraction. On the basis of weight postfusion and multilevel-resolution aggregation, IGCN not only reduces the cost of calculating the interpolation operation but also improves the model's performance. We validate the performance of IGCN on both point cloud classification and segmentation tasks and explore the contribution of each module of our model through ablation experiments. Furthermore, we embed the IGCN point cloud feature extraction module as a plug-and-play module into other frameworks and perform point cloud registration experiments.

Assessing the impact of conceptual mineral systems uncertainty on prospectivity predictions

The past two decades have seen a rapid adoption of artificial intelligence methods applied to mineral exploration. More recently, the easier acquisition of some types of data has inspired a broad literature that has examined many machine learning and modelling techniques that combine exploration criteria, or ‘features’, to generate predictions for mineral prospectivity. Central to the design of prospectivity models is a ‘mineral system’, a conceptual model describing the key geological elements that control the timing and location of economic mineralisation. The mineral systems model defines what constitutes a training set, which features represent geological evidence of mineralisation, how features are engineered and what modelling methods are used. Mineral systems are knowledge-driven conceptual models, thus all parameter choices are subject to human biases and opinion so alternative models are possible. However, the effect of alternative mineral systems models on prospectivity is rarely compared despite the potential to heavily influence final predictions. In this study, we focus on the effect of conceptual uncertainty on Fe ore prospectivity models in the Hamersley region, Western Australia. Four important considerations are tested. (1) Five different supergene and hypogene conceptual mineral systems models guide the inputs for five forest-based classification prospectivity models model. (2) To represent conceptual uncertainty, the predictions are then combined for prospectivity model comparison. (3) Representation of three-dimensional objects as two-dimensional features are tested to address commonly ignored thickness of geological units. (4) The training dataset is composed of known economic mineralisation sites (deposits) as ‘positive’ examples, and exploration drilling data providing ‘negative’ sampling locations. Each of the spatial predictions are assessed using independent performance metrics common to AI-based classification methods and subjected to geological plausibility testing. We find that different conceptual mineral systems produce significantly different spatial predictions, thus conceptual uncertainty must be recognised. A benefit to recognising and modelling different conceptual models is that robust and geologically plausible predictions can be made that may guide mineral discovery.

Do-It-Yourself digital archaeology: Introduction and practical applications of photography and photogrammetry for the 2D and 3D representation of small objects and artefacts

Photography and photogrammetry have recently become among the most widespread and preferred visualisation methods for the representation of small objects and artefacts. People want to see the past, not only know about it; and the ability to visualise objects into virtually realistic representations is fundamental for researchers, students and educators. Here, we present two new methods, the 'Small Object and Artefact Photography' ('SOAP') and the 'High Resolution "DIY" Photogrammetry' ('HRP') protocols. The 'SOAP' protocol involves the photographic application of modern digital techniques for the representation of any small object. The 'HRP' protocol involves the photographic capturing, digital reconstruction and three-dimensional representation of small objects. These protocols follow optimised step-by-step explanations for the production of high-resolution two- and three-dimensional object imaging, achievable with minimal practice and access to basic equipment and softwares. These methods were developed to allow anyone to easily and inexpensively produce high-quality images and models for any use, from simple graphic visualisations to complex analytical, statistical and spatial analyses.

OPTIMIZED CONFIGURATIONS FOR MICRO-PHOTOGRAMMETRIC SURVEYING ADAPTABLE TO MACRO OPTICS AND DIGITAL MICROSCOPE

Abstract. The configuration of new survey approaches for digitizing tiny artefacts is gradually emerging in favour of the related results sharing in new modalities such as 3D printing and or Cultural Heritage open-access datasets. Unfortunately, due to the still high cost of the instrumentations and the time required for specialized operators training, both the digital documentation of small artefacts and the dissemination of 3D data are still a long way from becoming truly mainstream practices.Alternative solutions, often at low cost, could be considered, involving the use of passive sensors for image-based modelling processes, relying on a widespread technology that is now within everyone’s reach. Therefore, we intend to meet the demand for the three-dimensional representation of small objects with complex surfaces and sub-millimetre morphological characteristics by designing several custom accessories that optimize the photogrammetric workflow while maintaining very high metric rigour.In this current work, the authors will focus on researching the most suitable acquisition method and hardware setup to achieve a digital twin of a complex and detailed cuneiform tablet replica using the now widely available on the market digital portable microscopes, able to achieve high magnification. The results were compared with a reference dataset from an active sensor acquisition for the necessary procedure validations.

Mathematical representation of three-dimensional objects as a means of innovative vocational guidance of students

Mathematical representation of three-dimensional objects as a means of innovative vocational guidance of students

Orthogonal multi-view three-dimensional object representations in memory revealed by serial reproduction

Orthogonal multi-view three-dimensional object representations in memory revealed by serial reproduction

Fast multiscale reconstruction for Cryo-EM.

We present a multiscale reconstruction framework for single-particle analysis (SPA). The representation of three-dimensional (3D) objects with scaled basis functions permits the reconstruction of volumes at any desired scale in the real-space. This multiscale approach generates interesting opportunities in SPA for the stabilization of the initial volume problem or the 3D iterative refinement procedure. In particular, we show that reconstructions performed at coarse scale are more robust to angular errors and permit gains in computational speed. A key component of the proposed iterative scheme is its fast implementation. The costly step of reconstruction, which was previously hindering the use of advanced iterative methods in SPA, is formulated as a discrete convolution with a cost that does not depend on the number of projection directions. The inclusion of the contrast transfer function inside the imaging matrix is also done at no extra computational cost. By permitting full 3D regularization, the framework is by itself a robust alternative to direct methods for performing reconstruction in adverse imaging conditions (e.g., heavy noise, large angular misassignments, low number of projections). We present reconstructions obtained at different scales from a dataset of the 2015/2016 EMDataBank Map Challenge. The algorithm has been implemented in the Scipion package.

Tabletowe dzieci. Ile zła wyrządza małym dzieciom tablet reklamowany jako najlepsza zabawka dla twojego dziecka. Ku rozwadze dorosłym, którzy temu ulegają

In the article, I present the findings of scientific insight into issues that I call tablet children. I provide alarming data on the number of children aged 6 months and a little bit older who are given access to tablets and smartphones by adults. I quote the most important findings included in the theory of representation by Jerome S. Bruner to explain the following: – What makes babies and toddlers use tablets and smartphones in a remarkably efficient way; – Adverse differences in representations created by children based on experiences gathered in the world of real objects and in the virtual world; – Distortions in the outlines of mental representations formed by young children when they watch images on tablet and smartphone screens too frequently. Being given access to these devices is particularly dangerous for young children, who have not yet created the outlines of the representations of three-dimensional objects and three-dimensional qualities of space in their minds. Distortions in the outlines of representations are difficult to fix as subsequent experiences only complement and expand the existing representations. Since the existing representations take part in creating new representations, the new ones are not fully correct either. I also argue the need for serious research that should aim to determine the far-reaching results of tablets and smartphones being available to babies and young children. This will help to come to terms with these devices educationally and also to determine when and for how long they can be made available to children so that they are safe for children's mental development.

CBCT: A swap to conventional orthodontic imaging

Conventional imaging techniques are essentially two-dimensional representations of three-dimensional objects and suffer from several restrains. Cone-beam computed tomography (CBCT), a world shattering revolution, offered a unique platform for orthodontic diagnosis and treatment planning. The aim of this article is to provide a broad overview of applications of CBCT in orthodontia.

A Multispectral 3-D Vision System for Invertebrate Detection on Crops

Real-time detection and identification of invertebrates on crops is a necessary capability for integrated pest management, however, this challenging task has not been well-solved. Multispectral or hyperspectral machine vision systems have shown advantages for efficient and accurate detection and identification of certain invertebrate pests. However, only using spectral information has limited the capability for detection, especially for some camouflaged pests on host plants. Three-dimensional (3-D) object representations are being intensively studied for multiview object recognition and scene understanding in many fields. However, because of the lack of proper data collection methods and robust algorithms, 3-D technologies have not yet attained applications for detecting invertebrates. We have developed a multispectral 3-D vision system, which can create denser point clouds of plants and pests using the multispectral images of ultraviolet, blue, green, red, and near-infrared. An algorithm named local variance of normals was designed, which can distinguish broad leaves from relatively larger pests in noisy point clouds. The vision system could aid integrated pest management systems for pest monitoring, or could be used as a sensor of an automatic pesticide sprayer.

The programmable hexapod

The Gough-Stewart platform (GSP) is a variable strut, programmable octahedral hexapod that uses six computer-controlled linear actuators to support a moveable base. These devices have been developed for a wide range of commercial uses including flight and vehicle simulators, high-precision tools, mining machines and medical instruments including programmable external fixators. The prototype hexapod external was introduced in France in 1986 and improvements in component design and computer algorithms have broadened the clinical repertoire of these devices. An increase in the number of available systems is expected in the next 18 months, owing to the expanding indications for this technology, in addition to termination of long standing patent arrangements and the associated commercial imperatives. These versatile platforms have clinical applications in acute fracture fixation; deformity surgery and limb salvage and provide an attractive combination of flexibility and ease of application. Contemporary orthopaedic practice is illustrated by two-dimensional radiological images, presented in standard anteroposterior and medio-lateral orthogonal planes. These are simplified ‘two axis’ representations of complex three-dimensional objects. It would not be possible to use an automated device to predictably reconstruct a deformed bone without the ability to mathematically describe the positions of the individual components. Pythagoras (c.570 BCE – c.495 BCE) and Euclid (c.300 BCE) are credited with defining the fundamentals of 2D and 3D geometry, and this was refined by Appolonius (c.262 BCE – c. 190 BCE), who anticipated Cartesian geometry by 1800 years. Pappus (c. A.D. 290 – c. 350) introduced a formalised approach to this area of mathematics and described a form of geometry that was not based on the concept of distance. This began with the study of the relationship between points and lines in 2D space and developed into the discipline of projective geometry. The introduction of realism in art in the Italian Renaissance relied on …

Three dimensional reconstruction by electron microscopy in the life sciences: An introduction for cell and tissue biologists.

Early applications of transmission electron microscopy (TEM) in the life sciences have contributed tremendously to our current understanding at the subcellular level. Initially limited to two-dimensional representations of three-dimensional (3D) objects, this approach has revolutionized the fields of cellular and structural biology-being instrumental for determining the fine morpho-functional characterization of most cellular structures. Electron microscopy has progressively evolved towards the development of tools that allow for the 3D characterization of different structures. This was done with the aid of a wide variety of techniques, which have become increasingly diverse and highly sophisticated. We start this review by examining the principles of 3D reconstruction of cells and tissues using classical approaches in TEM, and follow with a discussion of the modern approaches utilizing TEM as well as on new scanning electron microscopy-based techniques. 3D reconstruction techniques from serial sections and (cryo) electron-tomography are examined, and the recent applications of focused ion beam-scanning microscopes and serial-block-face techniques for the 3D reconstruction of large volumes are discussed. Alternative low-cost techniques and more accessible approaches using basic transmission or field emission scanning electron microscopes are also examined.

Statistics of three-dimensional objects and object representation

Statistics of three-dimensional objects and object representation

An Integrated Geometric Modeling Methodology for 2.5D Cylindrical Prismatic Part for Computer Aided Process Planning

The field of solid modeling has created numerous techniques for unambiguous computer representations of three-dimensional objects. Its data structures and algorithms have been used in a broad range of applications: Computer-Aided Design and Computer-Aided Manufacturing (CAD/ CAM), robotics, computer vision, computer graphics and visualization, virtual reality, etc. This research paper is used to generate process plan from feature-based modeling, based on an integrated geometric modeling system that supports both feature-based modeling and information storage. Present system is developed only for milling components and limited to selective machining features for prismatic components and further implemented for more machining features to develop algorithms for modeling the components through the input of machining features. As a result, feature information is directly available to downstream activities, and feature extraction is no longer needed. The various systematic steps involved in this approach are study of Design, identification of Features, selection of Processes, Tools and Machines, Machining and Inspection [DFPTMMI]. Machining features generated in the design stage are recognized and stored under the Visual Basic control of CATIA software ActiveX interface. Algorithms are developed for individual features and these algorithms are embedded in Visual Basic forms. This system is discussed and suited for 2.5 Dimensional part approach, however, that can be extended to 3 dimensional prismatic part and complex features machining. Finally a process planning chart has been presented as a model process planning.

A tomographic imagery segmentation methodology for three-phase geomaterials based on simultaneous region growing

X-ray computed tomography is a powerful non-destructive technique used in many domains to obtain the three-dimensional representation of objects, starting from the reconstitution of two-dimensional images of radiographic scanning. This technique is now able to analyze objects within a few micron resolutions. Consequently, X-ray microcomputed tomography opens perspectives for the analysis of the fabric of multiphase geomaterials such as soils, concretes, rocks and ceramics. To be able to characterize the spatial distribution of the different phases in such complex and disordered materials, automated phase recognition has to be implemented through image segmentation. A crucial difficulty in segmenting images lies in the presence of noise in the obtained tomographic representation, making it difficult to assign a specific phase to each voxel of the image. In the present study, simultaneous region growing is used to reconstitute the three-dimensional segmented image of granular materials. First, based on a set of expected phases in the image, regions where specific phases are sure to be present are identified, leaving uncertain regions of the image unidentified. Subsequently, the identified regions are grown until growing phases meet each other with vanishing unidentified regions. The method requires a limited number of manual parameters that are easily determined. The developed method is illustrated based on three applications on granular materials, comparing the phase volume fractions obtained by segmentation with macroscopic data. It is demonstrated that the algorithm rapidly converges and fills the image after a few iterations.

Three-dimensional chiral objects and their star graph representations

Planar chirality properties can be analysed using n-polyominoes and graphs. In this paper we study graph representations of three-dimensional chiral objects and discuss the generalization of planar case. We show that graph representations of three-dimensional chiral objects can be star graphs.