Visualization Purposes Research Articles

Imperceptible non-blind watermarking and robustness against tone mapping operation attacks for high dynamic range images

High dynamic range (HDR) imaging has experienced a widespread during the recent years through various technologies, including social network applications, which necessitates robust watermarking schemes to protect the copyright and image authentication. As watermarked high dynamic range images need to be tone mapped for visualization purposes on the traditional low dynamic range displays, the associated tone mapping operators (TMOs) can be deemed inevitable attacks. In this paper, we show that the state-of-the-art non-blind watermarking algorithms are vulnerable to the TMO’s attacks. Based on the results of our investigation, we propose an improved non-blind watermarking method and extensively evaluate with state-of-the-art non-blind watermarking schemes using a broad set of TMOs’ attacks. The proposed method first divides a given host image into patches, each of which is then decomposed using the discrete wavelet transform (DWT). The high-high sub-band of DWT is then passed through chirp-z transformation, followed by QR decomposition. The proposed solution embeds the watermark into each of value of the upper triangular matrix obtained from QR decomposition. The efficiency of the proposed embedding scheme is evaluated by applying 14 different TMOs on the watermarked image and extracting the embedded watermark. The average of 100 normalized correlation values for each image is then taken into account as a criterion for comparison, which demonstrates the noticeably stronger performance of the proposed watermarking scheme with respect to the state-of-the-art non-blind watermarking alternatives.

Microwave Heating Visualization for Carbon Fibers Composite Material: Development of Tunable Microstrip Structures

The visualization of carbon fibers polyether ether ketone (PEEK) composite material heating for a grounded coplanar waveguide and a stepped impedance low-pass filter by the thermal camera is performed. The purpose of such visualization is to characterize electromagnetic field influence on the diagonally anisotropic composite material and find out its application opportunity. COMSOL Multiphysics simulation has been done in order to understand heating principles and origin. Experimental results were in a good agreement with simulations and they showed that the characteristics of the microstrip structures can be modulated/tuned by simple rotation of the composite material. Finally, a tunable application by the carbon/PEEK composite material for the microstrip low-pass filter was developed due to the microwave absorption selectivity dependence on the composite material orientation.

A Viewable Indexing Structure for the Interactive Exploration of Dynamic and Large Image Collections

Thanks to the capturing devices cost reduction and the advent of social networks, the size of image collections is becoming extremely huge. Many works in the literature have addressed the indexing of large image collections for search purposes. However, there is a lack of support for exploratory data mining. One may want to wander around the images and experience serendipity in the exploration process. Thus, effective paradigms not only for organising, but also visualising these image collections become necessary. In this article, we present a study to jointly index and visualise large image collections. The work focuses on satisfying three constraints. First, large image collections, up to million of images, shall be handled. Second, dynamic collections, such as ever-growing collections, shall be processed in an incremental way, without reprocessing the whole collection at each modification. Finally, an intuitive and interactive exploration system shall be provided to the user to allow him to easily mine image collections. To this end, a data partitioning algorithm has been modified and proximity graphs have been used to fit the visualisation purpose. A custom web platform has been implemented to visualise the hierarchical and graph-based hybrid structure. The results of a user evaluation we have conducted show that the exploration of the collections is intuitive and smooth thanks to the proposed structure. Furthermore, the scalability of the proposed indexing method is proved using large public image collections.

Metode vizuelnog upravljanja robotskih sistema - pregled stanja u oblasti istraživanja

This paper surveys the methods used for visual servoing of robotic systems, where the main focus is on mobile robot systems. The three main areas of research include the Direct Visual Servoing, stereo vision systems, and artificial intelligence in visual servoing. The standard methods such as Image-Based Visual Servoing (IBVS) and Position-Based Visual Servoing (PBVS) are analyzed and compared with the new method named Direct Visual Servoing (DVS). DVS methods have better accuracy, compared to IBVS and PBVS, but have limited convergence area. Because of their high accuracy, DVS methods are suitable for integration into hybrid systems. Furthermore, the use of the stereo systems for visual servoing is comprehensively analyzed. The main contribution of the stereo system is the accurate depth estimation, which is critical for many visual servoing tasks. The use of artificial intelligence (AI) in visual servoing purposes has also gained popularity over the years. AI techniques give visual servoing controllers the ability to learn by using predefined examples or empirical knowledge. The learning ability is crucial for the implementation of robotic systems in a real-world dynamic manufacturing environment. Also, we analyzed the use of visual odometry in combination with a visual servoing controller for creating more robust and reliable positioning system.

MazeSuite 3: A design, presentation and analysis platform for spatial navigation, cognitive neuroscience and neuroengineering applications

MazeSuite 3: A design, presentation and analysis platform for spatial navigation, cognitive neuroscience and neuroengineering applications

New Gradient Methods for Bandwidth Selection in Bivariate Kernel Density Estimation

The bivariate kernel density estimator is fundamental in data smoothing methods especially for data exploration and visualization purposes due to its ease of graphical interpretation of results. The crucial factor which determines its performance is the bandwidth. We present new methods for bandwidth selection in bivariate kernel density estimation based on the principle of gradient method and compare the result with the biased cross-validation method. The results show that the new methods are reliable and they provide improved methods for a choice of smoothing parameter. The asymptotic mean integrated squared error is used as the measure of performance of the new methods.

Multi-model visualization based on integration of data models in semantic network environment

The paper considers the problem of integration of data models for visualization purpose. Integration implies that the set of the data transformations from one model to another is defined and may be realized. A set of visual elements with attached attributes is offered as the final result, this set being an abstraction of the representation of vector graphic information. Conceptual structures of models to be integrated may start acting during computation process required for getting visual representation differently. It is necessary that differently acting conceptual structures (concepts and frames) be parted or separated to provide correct visualization. To have practical separation it is suggested to include in the supporting system the component called semantic separator. In general case data separation is a cognitive task. Use of methods of applicative computational systems gives some advantages. For example, it gives good means for supporting a default mode. Prototype implementations of methods of the semantic separation were tested in developing computer aided law applications.

Design and development of the human middle ear to examine dynamic responses

The research emphasis on the development of Finite Element (FE) model of the human middle ear (ME) that comprises of the tympanic membrane (TM), three auditory ossicles, various ligament structures, and muscles. Due to the complex geometrical shape, conventional modeling techniques leads to inaccuracy in model morphology. A widely held approach to model such complex biological components is by using micro X-ray computed tomography (μCT). High-resolution 3-Dimensional morphology models of the human ME are published and made available for non-commercial research purpose, but these published models are in form of surface meshes and holds good for visualization purpose and 3-D printing only. To simulate and analyze the dynamic behavior of ME components it is essential to convert these surface meshes (stereolithography files) into volume meshes and hence these geometrical models necessitate further processing. Additionally, an attempt has been made to design and incorporate certain missing geometries to represent a complete ME model. The intent of current study is to develop a resourceful anatomically precise FE model of the human ME which is capable of incorporating variation in parameters and corresponds in view of that.

Digital 3D reconstructed models A proposition for structuring visualisation workflows using semantic technologies for recommendations

It is common for cultural heritage applications to use spatial and/or spectral data for documentation, analysis and visualisation. Knowledge on data requirements coming from the cultural heritage application and technical alternatives to generate the required data based on object characteristics and other influencings factors paves the way for the optimal selection of a recording technology. It is a collaborative process requiring knowledge of experts from cultural heritage domains and technical domains. Currently, this knowledge is structured and stored in an ontology (so-called COSCHKR). It has the purpose to support CH experts not familiar with technologies through prescribing an optimal spatial or spectral recording strategy adapted to the physical characteristics of the cultural heritage object and the data requirements of the targeted CH application. The creation of digital 3D reconstructed models for analysis and visualisation purposes is getting more and more common within humanities disciplines. Therefore, an implementation of mechanisms involved in visualisation applications into this ontology would have huge benefits in creating a powerful recommendation solution. A structured view on such project workflows facilitates a rough match with the existing knowledge representation. Illustrating the overall structure of COSCHKR, this paper addresses and discusses challenges in structuring the processes of cultural heritage visualisation and implementing these into the ontology.

Clustering of samples and variables with mixed-type data.

Analysis of data measured on different scales is a relevant challenge. Biomedical studies often focus on high-throughput datasets of, e.g., quantitative measurements. However, the need for integration of other features possibly measured on different scales, e.g. clinical or cytogenetic factors, becomes increasingly important. The analysis results (e.g. a selection of relevant genes) are then visualized, while adding further information, like clinical factors, on top. However, a more integrative approach is desirable, where all available data are analyzed jointly, and where also in the visualization different data sources are combined in a more natural way. Here we specifically target integrative visualization and present a heatmap-style graphic display. To this end, we develop and explore methods for clustering mixed-type data, with special focus on clustering variables. Clustering of variables does not receive as much attention in the literature as does clustering of samples. We extend the variables clustering methodology by two new approaches, one based on the combination of different association measures and the other on distance correlation. With simulation studies we evaluate and compare different clustering strategies. Applying specific methods for mixed-type data proves to be comparable and in many cases beneficial as compared to standard approaches applied to corresponding quantitative or binarized data. Our two novel approaches for mixed-type variables show similar or better performance than the existing methods ClustOfVar and bias-corrected mutual information. Further, in contrast to ClustOfVar, our methods provide dissimilarity matrices, which is an advantage, especially for the purpose of visualization. Real data examples aim to give an impression of various kinds of potential applications for the integrative heatmap and other graphical displays based on dissimilarity matrices. We demonstrate that the presented integrative heatmap provides more information than common data displays about the relationship among variables and samples. The described clustering and visualization methods are implemented in our R package CluMix available from https://cran.r-project.org/web/packages/CluMix.

Incremental volumetric and Dual Kriging remapping methods

The transfer of variables between distinct spatial domains is a problem shared by many research fields. Among other applications, it may be required for visualization purposes or for intermediate analysis of a process. In any case, two important factors must be considered: accuracy and computational performance. The accuracy becomes more important when the results have an impact on the subsequent stages of the process' analysis, as it could lead to incorrect results. The computational performance is a permanent requirement due to the ever-increasing complexity of the analysed processes. The aim of this work is to present a new remapping method, based on Dual Kriging interpolation, developed to enable accurate and efficient variable transfer operations between two different domains, discretized with hexahedral finite elements. Two strategies are proposed, which take into account different selections of interpolation points and are based on specific Finite Element Method features. They are compared with the Incremental Volumetric Remapping method in two remapping examples, one of which includes a trimming operation, highlighting their advantages and limitations. The results show that the Dual Kriging remapping method, combined with a 2D selection strategy for the donor points, can contribute to increase the accuracy of the state variables remapping operation, particularly when they present a strong gradient along the stacking direction.

A pattern-based approach for developing creativity applications supported by surface computing

An activity model for applications focused on creativity.Building blocks for constructing applications designed for creativity.By relying on our building blocks, applications were implemented in short time.Our building blocks prove the model's expressivity for describing creativity sessions. Whereas creativity tasks have traditionally been supported by conventional media and tools (such as paper, pens, scissors and glue); mobile phones, tablets and other devices based on interactive surfaces are increasingly been used as additional support. Large-sized multi-touch interactive surfaces appear as an interesting alternative for supporting creativity processes and for supporting synchronous collocated collaboration. However, they have mostly been usedfor visualization and navigation purposes. Their use as authoring means, which would be essential in creativity tasks, has only begun to be explored. Applications and platforms that have been developed in this area rely on low-level primitives for implementing representation of ideas and discussions. We have identified a significant gap between the level of development tools and the abstractions required by end-user applications that aim to support creativity processes using interactive surfaces. This gap makes it difficult for developers to build applications that provide richer, more flexible support for innovators working collaboratively around interactive surfaces. Based upon a thorough analysis of existing applications and user practices in the field, we have identified the key actions and interaction patterns that take place during collaborative creativity sessions. Thus, we propose ISCALI (Innovation Solutions Centered on Activities for Large-sized Interfaces), a model that can be used both for describing and for prescribing the role of multi-touch surfaces in collaborative creativity tasks. In accordance to Activity Centered Design, ISCALI comprises three major components: activities, actions and operations. The central activities within the processes of creativity comprise generation, organization and evaluation of ideas. Each of these activities encompasses sets of actions. Finally, several operation sets achieve the goal of each of the actions. Based upon our model, we designed a general architecture for collaborative creativity applications. This architecture addresses the development gap through a proposed set ofbuilding blocks. These building blocks implement the main interaction patterns needed for stimulating creativity tasks that rely on interactive surfaces. We have implemented prototypical versions of these building blocks, referred to as TOKAs (Touch Operations for Creative Activities), and have made them available to developers. Independent developers have implemented applications that facilitate the use of various methodologies that foster creativity and synchronous collocated collaboration. These developers have taken advantage of the availability of TOKAs. The implementation and use of TOKAs demonstrate ISCALI's expressivity for describing and guiding the development of applications that support collaborative creativity on top of interactive surfaces.

Development of stratified approach to software defined networks simulation

The stratified approach to software defined networks simulation has been proposed. It is based on Discrete Event System Specification formalism, atomic and coupled models concepts usage. The approach is aimed at simulation within the Windows environment, with an accent on the easiness of model reconfiguration. The proposed approach is also devoted to simulation-related overheads decrease. The atomic models of active (controller, switch, host) and passive (link) network components have been proposed. The coupled model of a software defined network comprising atomic models of active and passive components has been proposed. The estimations of the resulting coupled model complexity, with respect to the number of components basic atomic models, have been given. During experimentation, the pingall command usage scenario has been considered. For this purpose, the emulation via Mininet environment and the simulation on a basis of the proposed approach have been conducted. It has been shown that discrete-event simulation on a basis of the proposed approach is significantly less time-consuming. During the approach usage within the Windows environment, the absence of the need to utilize the Xming X Server and PuTTY utility for the purpose of visualization has been faced. The validity of the approach has been proven on a basis of the obtained experimental data. The adequacy of the resulting coupled simulation model of the network has been proven with t-criterion. The proposed approach can be used for the purpose of software defined networks validation with an accent on non-functional properties

CALCULATING SOLAR ENERGY POTENTIAL OF BUILDINGS AND VISUALIZATION WITHIN UNITY 3D GAME ENGINE

Abstract. Solar energy modelling is increasingly popular, important, and economic significant in solving energy crisis for big cities. It is a clean and renewable resource of energy that can be utilized to accommodate individual or group of buildings electrical power as well as for indoor heating. Implementing photovoltaic system (PV) in urban areas is one of the best options to solve power crisis over expansion of urban and the growth of population. However, as the spaces for solar panel installation in cities are getting limited nowadays, the available strategic options are only at the rooftop and façade of the building. Thus, accurate information and selecting building with the highest potential solar energy amount collected is essential in energy planning, environmental conservation, and sustainable development of the city. Estimating the solar energy/radiation from rooftop and facade are indeed having a limitation - the shadows from other neighbouring buildings. The implementation of this solar estimation project for Istanbul uses CityGML LoD2-LoD3. The model and analyses were carried out using Unity 3D Game engine with development of several customized tools and functionalities. The results show the estimation of potential solar energy received for the whole area per day, week, month and year thus decision for installing the solar panel could be made. We strongly believe the Unity game engine platform could be utilized for near future 3D mapping visualization purposes.

Characterisation of ultrasound contrast agents for subharmonic imaging for use in quantitative dynamic contrast enhanced ultrasound

Dynamic contrast enhanced ultrasound (DCE-US) using ultrasound contrast agents (UCA) is a non-invasive method of imaging the microvasculature, employing harmonic signal detection. UCAs are currently used clinically for qualitative visualisation purposes predominately. There is current interest in detecting the subharmonic component, known to be generated by UCAs but not tissue, which may increase sensitivity, although optimal transmission parameters remain to be determined. The aim of this work was to establish an acoustic characterisation system for use in establishing optimal subharmonic parameters. A reflection-based broadband acoustic system for UCA characterisation was developed and used to measure the attenuation of the UCA Definity™ (Lantheus, USA) across the diagnostic frequency range 1–10 MHz. A Coulter counter (aperture size 20 μm) was used to establish the size distribution (1.3–10 μm) and concentration of the UCA (1.2–1.4 × 109 bubbles/ml). Using a pulse-echo substitution method and single element transducer (Olympus, USA) the attenuation was measured of a solution of Definity diluted in saline, made up to an ‘in vivo’ concentration of 800,000 bubbles/ml. Pressure levels and frequency content, which influence the production of subharmonic signal, were also investigated using a through-transmission set-up with a needle hydrophone (Precision Acoustics, UK). A through-transmission narrowband characterization system for use in subharmonic characterization was also developed and pressure levels above the subharmonic threshold of ∼50 kPa were measured. An attenuation of 1.1 dB/cm was measured at 5 MHz, which is close to that reported in literature [1] . The developed broadband and narrowband systems are enabling an in-depth investigation of optimal transmit settings to maximise the subharmonic signal. Acknowledgement Irish Research Council, Government of Ireland Postgraduate Scholarship.

COMPUTER GRAPHICS MEETS IMAGE FUSION: THE POWER OF TEXTURE BAKING TO SIMULTANEOUSLY VISUALISE 3D SURFACE FEATURES AND COLOUR

Abstract. Since a few years, structure-from-motion and multi-view stereo pipelines have become omnipresent in the cultural heritage domain. The fact that such Image-Based Modelling (IBM) approaches are capable of providing a photo-realistic texture along the threedimensional (3D) digital surface geometry is often considered a unique selling point, certainly for those cases that aim for a visually pleasing result. However, this texture can very often also obscure the underlying geometrical details of the surface, making it very hard to assess the morphological features of the digitised artefact or scene. Instead of constantly switching between the textured and untextured version of the 3D surface model, this paper presents a new method to generate a morphology-enhanced colour texture for the 3D polymesh. The presented approach tries to overcome this switching between objects visualisations by fusing the original colour texture data with a specific depiction of the surface normals. Whether applied to the original 3D surface model or a lowresolution derivative, this newly generated texture does not solely convey the colours in a proper way but also enhances the smalland large-scale spatial and morphological features that are hard or impossible to perceive in the original textured model. In addition, the technique is very useful for low-end 3D viewers, since no additional memory and computing capacity are needed to convey relief details properly. Apart from simple visualisation purposes, the textured 3D models are now also better suited for on-surface interpretative mapping and the generation of line drawings.

An Interactive Web Mapping Visualization of Urban Air Quality Monitoring Data of China

In recent years, main cities in China have been suffering from hazy weather, which is gaining great attention among the public, government managers and researchers in different areas. Many studies have been conducted on the topic of urban air quality to reveal different aspects of the air quality problem in China. This paper focuses on the visualization problem of the big air quality monitoring data of all main cities on a nationwide scale. To achieve the intuitive visualization of this data set, this study develops two novel visualization tools for multi-granularity time series visualization (timezoom.js) and a dynamic symbol declutter map mashup layer for thematic mapping (symadpative.js). With the two invented tools, we develops an interactive web map visualization application of urban air quality data of all main cities in China. This application shows us significant air pollution findings at the nationwide scale. These results give us clues for further studies on air pollutant characteristics, forecasting and control in China. As the tools are invented for general visualization purposes of geo-referenced time series data, they can be applied to other environmental monitoring data (temperature, precipitation, etc.) through some configurations.

Noise properties of Fourier deconvolution for time-domain electromagnetic soundings

The transient electromagnetic method (TEM) is widely used for mapping the earth’s subsurface resistivity structures, e.g., for groundwater or mineral exploration, using airborne and ground-based systems. Data from TEM surveys can be modified using Fourier deconvolution to correct for instrument drift, increase apparent bandwidth, or alter the apparent excitation waveform, e.g., to fuse or compare measurements from different systems, for visual presentation purposes, or to make the data compatible with a specific processing or inversion code. Although this method has been applied in several studies, little attention has been devoted to its properties with regard to noise. Using a generic analytical system model and examples featuring synthetic and field data, we perform a detailed analysis of the noise properties of Fourier deconvolution in the context of TEM. We find that although the effects from stationary noise are trivial, effects from nonstationary noise are less intuitive and more severe, e.g., causing on-time noise phenomena to degrade off-time data. In general, we observe that the method decreases the signal-to-noise ratio, and our recommendation is therefore that Fourier deconvolution should only be applied when it is desirable for presentation purposes or when strictly necessary for processing or inversion.

Ray tracing synthesis of spatial curve images built by the spherical interpolation method

The problem of visualization by ray tracing of spatial curves specified by interpolation points and smoothed by the method of spherical interpolation was solved. The method of spherical interpolation was developed mainly for interpolation of a triangulated surface with the purpose of further visualization of this surface by the method of ray tracing. This method is universal and enables the construction of flat and three-dimensional smooth curves drawn through arbitrarily set points. The paper presents analytical relationships for realization of each stage of construction of a spatial curve by this method. To visualize a spatial curve, an iterative process (IP) was developed for calculation of a point in the projection ray (PR) closest to some point of a mathematical spatial curve. To establish correspondence of the curve point to a pixel in a computer monitor screen, position of this point was determined relative to the space region bounded by the pyramid of pixel visibility. The proposed IP has a potential of wide parallelization of computations. An algorithm for constructing points of a spatial curve was developed with its step coinciding with the step of the iterative calculation process, which allows one to perform visualization algorithm and plot a curve point in a single pass of the IP. To this end, the point in the PR and the direction vector of the curve lie in the same plane perpendicular to the interpolated segment in each iteration step. This approach enables determination of the directing vector modulus for the subsequent stage of this iteration step. The proposed interpolation algorithm is based on the simplest algebraic surface, sphere, and does not use algebraic polynomials of the third and higher degrees. The results of the studies were confirmed by simulation of the visualization process using the Wolfram Mathematica software package. The problem of combining new methods for constructing smooth geometric shapes of spatial curves defined by straight lines and the method of ray tracing which on the whole will increase realism of the synthesized scenes in computer graphics was solved

Stability of visual outcome between 2 and 5 years following corneal transplantation in the UK

Background and AimsMany studies of corneal transplantation focus on graft failure or rejection as endpoints, or report visual outcomes at one postoperative time point. We aimed to study the stability...