feature identification

The purpose of this study was to identify consistent features in the signals supplied by a single inertial measurement unit (IMU), or thereof derived, for the identification of foot-strike and foot-off instants of time and for the estimation of stance and stride duration during the maintenance phase of sprint running. Maximal sprint runs were performed on tartan tracks by five amateur and six elite athletes, and durations derived from the IMU data were validated using force platforms and a high-speed video camera, respectively, for the two groups. The IMU was positioned on the lower back trunk (L1 level) of each athlete. The magnitudes of the acceleration and angular velocity vectors measured by the IMU, as well as their wavelet-mediated first and second derivatives were computed, and features related to foot-strike and foot-off events sought. No consistent features were found on the acceleration signal or on its first and second derivatives. Conversely, the foot-strike and foot-off events could be identified from features exhibited by the second derivative of the angular velocity magnitude. An average absolute difference of 0.005 s was found between IMU and reference estimates, for both stance and stride duration and for both amateur and elite athletes. The 95% limits of agreement of this difference were less than 0.025 s. The results proved that a single, trunk-mounted IMU is suitable to estimate stance and stride duration during sprint running, providing the opportunity to collect information in the field, without constraining or limiting athletes' and coaches' activities.

The purpose of this study was to identify consistent features in the signals supplied by a single inertial measurement unit (IMU), or thereof derived, for the identification of foot-strike and foot-off instants of time and for the estimation of stance and stride duration during the maintenance phase of sprint running. Maximal sprint runs were performed on tartan tracks by five amateur and six elite athletes, and durations derived from the IMU data were validated using force platforms and a high-speed video camera, respectively, for the two groups. The IMU was positioned on the lower back trunk (L1 level) of each athlete. The magnitudes of the acceleration and angular velocity vectors measured by the IMU, as well as their wavelet-mediated first and second derivatives were computed, and features related to foot-strike and foot-off events sought. No consistent features were found on the acceleration signal or on its first and second derivatives. Conversely, the foot-strike and foot-off events could be identified from features exhibited by the second derivative of the angular velocity magnitude. An average absolute difference of 0.005 s was found between IMU and reference estimates, for both stance and stride duration and for both amateur and elite athletes. The 95% limits of agreement of this difference were less than 0.025 s. The results proved that a single, trunk-mounted IMU is suitable to estimate stance and stride duration during sprint running, providing the opportunity to collect information in the field, without constraining or limiting athletes' and coaches' activities.

Rule-based forecasting (RBF) uses rules to combine forecasts from simple extrapolation methods. Weights for combining the rules use statistical and domain-based features of time series. RBF was originally developed, tested, and validated only on annual data. For the M3-Competition, three major modifications were made to RBF. First, due to the absence of much in the way of domain knowledge, we prepared the forecasts under the assumption that no domain knowledge was available. This removes what we believe is one of RBF's primary advantages. We had to re-calibrate some of the rules relating to causal forces to allow for this lack of domain knowledge. Second, automatic identification procedures were used for six time-series features that had previously been identified using judgment. This was done to reduce cost and improve reliability. Third, we simplified the rule-base by removing one method from the four that were used in the original implementation. Although this resulted in some loss in accuracy, it reduced the number of rules in the rule-base from 99 to 64. This version of RBF still benefits from the use of prior findings on extrapolation, so we expected that it would be substantially more accurate than the random walk and somewhat more accurate than equal weights combining. Because most of the previous work on RBF was done using annual data, we especially expected it to perform well with annual data.

Rule-based forecasting (RBF) uses rules to combine forecasts from simple extrapolation methods. Weights for combining the rules use statistical and domain-based features of time series. RBF was originally developed, tested, and validated only on annual data. For the M3-Competition, three major modifications were made to RBF. First, due to the absence of much in the way of domain knowledge, we prepared the forecasts under the assumption that no domain knowledge was available. This removes what we believe is one of RBF's primary advantages. We had to re-calibrate some of the rules relating to causal forces to allow for this lack of domain knowledge. Second, automatic identification procedures were used for six time-series features that had previously been identified using judgment. This was done to reduce cost and improve reliability. Third, we simplified the rule-base by removing one method from the four that were used in the original implementation. Although this resulted in some loss in accuracy, it reduced the number of rules in the rule-base from 99 to 64. This version of RBF still benefits from the use of prior findings on extrapolation, so we expected that it would be substantially more accurate than the random walk and somewhat more accurate than equal weights combining. Because most of the previous work on RBF was done using annual data, we especially expected it to perform well with annual data.

Figure 1: Illustrated here is the process of building a custom colormap for Sentinel2 CIR satellite data of the Wax Lake Delta. Starting from the left, one sees an image of the delta where brighter blue indicate regions with enhanced vegetation. Flow structures in the coastal ocean correspond to regions of enhanced sediment transport. In the central image, a separator pin divides land and water; a choice is made from the blues for the near-shore ocean and from the greens to evoke the land and foliage in the delta. In the finalized image, a brown is used in for the earth and blue variants are added to show greater detail in the water.

Colormapping is one of the simplest and most widely used data visualization methods within and outside the visualization community. Uniformity, order, discriminative power, and smoothness of continuous colormaps are the most important criteria for evaluating and potentially improving colormaps. We present a local and a global automatic optimization algorithm in Euclidean color spaces for each of these design rules in this work. As a foundation for our optimization algorithms, we used the CCC-Tool colormap specification (CMS); each algorithm has been implemented in this tool. In addition to synthetic examples that demonstrate each method's effect, we show the outcome of some of the methods applied to a typhoon simulation.

Fig. 1. Left: Screenshot of our new interactive test suite implemented in the CCC-Tool. Right: Two visualizations show at b the valley shaped Six-Hump Camel Function [15] for the area [−5, 5] × [−5, 5] and at a the LittleBit test function (Sect. 4.2.2). Special features of the Six-Hump Camel function are irregularly shaped troughs in the center of the area that are more than two orders smaller than the data range difference between center and boundary. The uniformly spaced colormap 1 cannot reveal the troughs, while the last nonlinear colormap 2 clearly shows the topological structure of the irregularities in the center of the domain.

Continuous colormaps are integral parts of many visualization techniques, such as heat-maps, surface plots, and flow visualization. Despite that the critiques of rainbow colormaps have been around and well-acknowledged for three decades, rainbow colormaps are still widely used today. One reason behind the resilience of rainbow colormaps is the lack of tools for users to create a continuous colormap that encodes semantics specific to the application concerned. In this paper, we present a web-based software system, CCC-Tool (short for Charting Continuous Colormaps) under the URL https://ccctool.com, for creating, editing, and analyzing such application-specific colormaps. We introduce the notion of "colormap specification (CMS)" that maintains the essential semantics required for defining a color mapping scheme. We provide users with a set of advanced utilities for constructing CMS's with various levels of complexity, examining their quality attributes using different plots, and exporting them to external application software. We present two case studies, demonstrating that the CCC-Tool can help domain scientists as well as visualization experts in designing semantically-rich colormaps.

Mapping a set of categorical values to different colors is an elementary technique in data visualization. Users of visualization software routinely rely on the default colormaps provided by a system, or colormaps suggested by software such as ColorBrewer. In practice, users often have to select a set of colors in a semantically meaningful way (e.g., based on conventions, color metaphors, and logological associations), and consequently would like to ensure their perceptual differentiation is optimized. In this paper, we present an algorithmic approach for maximizing the perceptual distances among a set of given colors. We address two technical problems in optimization, i.e., (i) the phenomena of local maxima that halt the optimization too soon, and (ii) the arbitrary reassignment of colors that leads to the loss of the original semantic association. We paid particular attention to different types of constraints that users may wish to impose during the optimization process. To demonstrate the effectiveness of this work, we tested this technique in two case studies. To reach out to a wider range of users, we also developed a web application called Colourmap Hospital.

In the era of big data, along with machine learning and databases, visualization has become critical to managing complex and overwhelming data problems. Vision science has been a foundation of data visualization for decades. As the systems that use visualization become more complex, advances in vision science are needed to provide fundamental theory to visualization researchers and practitioners to address emerging challenges. In this paper, we present our work on modeling the perception of correlation in bivariate visualizations using the Weber's Law. These Weber models can be applied to definitively compare and evaluate the effectiveness of these visualizations. We further demonstrate that the reason for this finding is that people approximate correlation using visual features that are known to follow the Weber's Law. These findings have multiple implications. One practical implication is that results like these can guide practitioners in choosing the appropriate visualization. In the context of big data, this result can lead to perceptually-driven computational techniques. For instance, it could be used for quickly sampling from big data in a way that preserves important data features, which can lead to better computational performance, a less overwhelming user experience, and more fluid interaction.

The prediction of behavioral covariates from functional MRI (fMRI) is known as brain reading. From a statistical standpoint, this challenge is a supervised learning task. The ability to predict cognitive states from new data gives a model selection criterion: prediction accuracy. While a good prediction score implies that some of the voxels used by the classifier are relevant, one cannot state that these voxels form the brain regions involved in the cognitive task. The best predictive model may have selected by chance non-informative regions, and neglected relevant regions that provide duplicate information. In this contribution, we address the support identification problem. The proposed approach relies on randomization techniques which have been proved to be consistent for support recovery. To account for the spatial correlations between voxels, our approach makes use of a spatially constrained hierarchical clustering algorithm. Results are provided on simulations and a visual experiment.

Operations engineering teams interact with complex data systems to make technical decisions that ensure the operational efficacy of their missions. To support these decision-making tasks, which may require elastic prioritization of goals dependent on changing conditions, custom analytics tools are often developed. We were asked to develop such a tool by a team at the NASA Jet Propulsion Laboratory, where rover telecom operators make decisions based on models predicting how much data rovers can transfer from the surface of Mars. Through research, design, implementation, and informal evaluation of our new tool, we developed principles to inform the design of visual analytics systems in operations contexts. We offer these principles as a step towards understanding the complex task of designing these systems. The principles we present are applicable to designers and developers tasked with building analytics systems in domains that face complex operations challenges such as scheduling, routing, and logistics.

A standard internet image search on a scientific topic is common practice, and offers a plethora of images. However, the suggested images provide neither a guarantee in the accuracy of the science content being portrayed, nor in their clarity or artistic elegance. Being curated by both scientists and artists, the online s-Ink collection (https://s-Ink.org) is, in contrast, an exchange platform for high quality, science-related graphical products. The collection is highly structured and effectively searchable via text, keyword, or category. As necessary, its hosted and linked content can be regularly updated to maintain pace with advances in both scientific understanding and graphic-related techniques. Key related information is provided alongside the graphical products, including an explanatory caption, the given license guiding further use, the names of their creators to value their work, and any related publication for proper citing and further in-depth information. By being open ...

Rule-based forecasting (RBF) uses rules to combine forecasts from simple extrapolation methods. Weights for combining the rules use statistical and domain-based features of time series. RBF was originally developed, tested, and validated only on annual data. For the M3-Competition, three major modifications were made to RBF. First, due to the absence of much in the way of domain knowledge, we prepared the forecasts under the assumption that no domain knowledge was available. This removes what we believe is one of RBF's primary advantages. We had to re-calibrate some of the rules relating to causal forces to allow for this lack of domain knowledge. Second, automatic identification procedures were used for six time-series features that had previously been identified using judgment. This was done to reduce cost and improve reliability. Third, we simplified the rule-base by removing one method from the four that were used in the original implementation. Although this resulted in some loss in accuracy, it reduced the number of rules in the rule-base from 99 to 64. This version of RBF still benefits from the use of prior findings on extrapolation, so we expected that it would be substantially more accurate than the random walk and somewhat more accurate than equal weights combining. Because most of the previous work on RBF was done using annual data, we especially expected it to perform well with annual data.

理科の教育では自然にたいする理解を深めるため多くの観察実験が用いられてきた。その場観察実験を考える上，走査電子顕微鏡（SEM）とエネルギー分散型Ｘ線分析装置（EDS）は大変便利な装置である。これらの装置を使い酸性雪の原因の一つがイオウ化合物であることを明らかにし，教材化することを試みた。また自然界の化学反応は岩石中の鉱物にその証拠を残している。隕石中のコンドリュールをカラーマッピングすることにより元素の分布を調べ元素間の反応が起こっていることを確かめることができる。また隕石中の金属鉄の存在から46億年前の地球大気の酸素分圧が現在より低かったことを示し，地球環境が変ってきたことを示す。The observation experiment is used for a deeper understanding of nature in the field of science education. When the specimen was observed by scanning electron microscope (SEM), we analyzed it by energy dispersive spectrometer (EDS) at that moment. SEM and EDS have been used as indispensable instruments for the educational material. We indicated by these instruments that one of causes for accid snow is sulfurate compound. Then we try to prepare the teaching materials. In the nature, chemical reaction was found in mineral from rock. Therefore we confirmed the reaction of minerals by the element concentration color map as Mg, Fe and Si etc. Also, the presence of metal iron in meteorite suggests t...

Continuous colormaps are integral parts of many visualization techniques, such as heat-maps, surface plots, and flow visualization. Despite that the critiques of rainbow colormaps have been around and well-acknowledged for three decades, rainbow colormaps are still widely used today. One reason behind the resilience of rainbow colormaps is the lack of tools for users to create a continuous colormap that encodes semantics specific to the application concerned. In this paper, we present a web-based software system, CCC-Tool (short for Charting Continuous Colormaps) under the URL https://ccctool.com, for creating, editing, and analyzing such application-specific colormaps. We introduce the notion of "colormap specification (CMS)" that maintains the essential semantics required for defining a color mapping scheme. We provide users with a set of advanced utilities for constructing CMS's with various levels of complexity, examining their quality attributes using different plots, and exporting them to external application software. We present two case studies, demonstrating that the CCC-Tool can help domain scientists as well as visualization experts in designing semantically-rich colormaps.

We present a computationally inexpensive, flexible feature identification method which uses a comparison of time series to identify a rank-ordered set of features in geophysically-sourced data sets. Many physical phenomena perturb multiple physical variables nearly simultaneously, and so features are identified as time periods in which there are local maxima of absolute deviation in all time series. Unlike other available methods, this method allows the analyst to tune the method using their knowledge of the physical context. The method is applied to a data set from a moored array of instruments deployed in the coastal environment of Monterey Bay, California, and a data set from sensors placed within the submerged Yax Chen Cave System in Tulum, Quintana Roo, Mexico. These example data sets demonstrate that the method allows for the automated identification of features which are worthy of further study.

Colormapping is one of the simplest and most widely used data visualization methods within and outside the visualization community. Uniformity, order, discriminative power, and smoothness of continuous colormaps are the most important criteria for evaluating and potentially improving colormaps. We present a local and a global automatic optimization algorithm in Euclidean color spaces for each of these design rules in this work. As a foundation for our optimization algorithms, we used the CCC-Tool colormap specification (CMS); each algorithm has been implemented in this tool. In addition to synthetic examples that demonstrate each method's effect, we show the outcome of some of the methods applied to a typhoon simulation.

The idea that there is no precedence for the amount of data that is being generated today, and that the need to explore and analyze this vast volumes of data has become anincreasingly difficult task that could benefit from using Data visualization is presented. It is pointed that the goals of data visualization are data-driven and depend largely on the type of application, but the final objective is to convey to people information that is hidden in large volumes of data. Finally, the visualization pipeline is presented to review aspects of visualization methodology and visualization tool design, to conclude that the true potential of visualization emerge from the interaction of the user with the visualization model. The paper concludes establishing that the current processes of digital transformation will increase the need for visual analytics tools.

A standard internet image search on a scientific topic is common practice, and offers a plethora of images. However, the suggested images provide neither a guarantee in the accuracy of the science content being portrayed, nor in their clarity or artistic elegance. Being curated by both scientists and artists, the online s-Ink collection (https://s-Ink.org) is, in contrast, an exchange platform for high quality, science-related graphical products. The collection is highly structured and effectively searchable via text, keyword, or category. As necessary, its hosted and linked content can be regularly updated to maintain pace with advances in both scientific understanding and graphic-related techniques. Key related information is provided alongside the graphical products, including an explanatory caption, the given license guiding further use, the names of their creators to value their work, and any related publication for proper citing and further in-depth information. By being open ...

Scientific visualization aims to present numerical values, or categorical information, in a way that enables the researcher to make an inference that furthers knowledge. Well-posed visualizations need to consider the characteristics of the data, the display environment, and human visual capacity. In the geosciences, visualizations are commonly applied to spatially varying continuous information or results. In this contribution we make use of a suite of newly written computer applications which enable spatially varying data to be displayed in a performant graphics environment. We present a comparison of color-mapping using illustrative color spaces (RGB, CIELAB). The interactive applications display the gradient paths through the chosen color spaces. This facilitates the creation of color-maps that accommodate the non-uniformity of human color perception, producing an image where genuine features are seen. We also take account of aspects of a dataset such as parameter uncertainty. For an illustrative case study using a seismic tomography result, we find that the use of RGB color-mapping can introduce non-linearities in the visualization, potentially leading to incorrect inference. Interpolation in CIELAB color space enables the creation of perceptually uniform linear gradients that match the underlying data, along with a simply computable metric for color difference, E. This color space assists accuracy and reproducibility of visualization results. Well-posed scientific visualization requires both "visual literacy" and "visual numeracy" on an equal footing with clearly written text. It is anticipated that this current work, with the included color-maps and software, will lead to wider usage of informed color-mapping in the geosciences.

As the 3D human face reconstruction is becoming very popular in recent times, it attracts many researchers. Construction of 3D human face using only two orthogonal images and twelve landmark features are the main context of the proposed approach. For3D object modeling, the Open Graphics Library (OpenGL) is used as the platform through which modeling, modification and rendering is performed on the morphable model. The proposed approach trails through semi-automatic identification of the facial landmark features, calculation of the 3D coordinates of human face, morphable model construction in OpenGL, reshaping of the morphable model and rendering of the morphable model. The facial landmark identification is semiautomatic method, as the module requires the manual interaction for marking the facial landmarks on the image. The reshaping of morphable model is required as the morphable model does not fit to the actual face in most of the cases. The morphable model is reshaped by calculating root mean square (RMS) error of face coordinates. The rendering process does not require a wide screen image because the approach performs rendering using input front face image and side face image as textures. Applications of this research help to overcome the disputes of fields like crime detection, 3D game characterization, the ornaments exhibition and in the area of medical technology like plastic surgery.

Now-a-days the volume of opinions about products, issues, events, and politics etc. on different social, e-commerce and review sites grows very rapidly. From both opinion holder and opinion target point of view, it is very difficult and time consuming task to analyze all the reviews from this massive amount of data on the web. So, there is a need of efficient method that automatically extracts the opinions and relevant features of the opinion target from the reviews and finally generates the feature wise summary. Sometimes people may use different words to express same feature, this may produce a misperception in the results during feature wise summary generation. To avoid this, we need to categorize similar features for precise classification of opinions based on these feature groups. Therefore, our study is targeting the most important tasks of feature based sentiment analysis that are feature extraction and feature categorization. This paper is about to cover the currently available techniques in these two areas. We have also focused on least addressed area in this domain giving an opportunity to researchers for future work.

Color interpolation is critical to many applications across a variety of domains, like color mapping or image processing. Due to the characteristics of the human visual system, color spaces whose distance measure is designed to mimic perceptual color differences tend to be non-Euclidean. In this setting, a generalization of established interpolation schemes is not trivial. This paper presents an approach to generalize linear interpolation to colors for color spaces equipped with an arbitrary non-Euclidean distance measure. It makes use of the fact that in Euclidean spaces, a straight line coincides with the shortest path between two points. Additionally, we provide an interactive implementation of our method for the CIELAB color space using the CIEDE2000 distance measure integrated into VTK and ParaView.

This work presents a new approach based on deep learning to automatically extract colormaps from visualizations. After summarizing colors in an input visualization image as a Lab color histogram, we pass the histogram to a pre-trained deep neural network, which learns to predict the colormap that produces the visualization. To train the network, we create a new dataset of ∼64K visualizations that cover a wide variety of data distributions, chart types, and colormaps. The network adopts an atrous spatial pyramid pooling module to capture color features at multiple scales in the input color histograms. We then classify the predicted colormap as discrete or continuous, and refine the predicted colormap based on its color histogram. Quantitative comparisons to existing methods show the superior performance of our approach on both synthetic and real-world visualizations. We further demonstrate the utility of our method with two use cases, i.e., color transfer and color remapping.

The idea that there is no precedence for the amount of data that is being generated today, and that the need to explore and analyze this vast volumes of data has become anincreasingly difficult task that could benefit from using Data visualization is presented. It is pointed that the goals of data visualization are data-driven and depend largely on the type of application, but the final objective is to convey to people information that is hidden in large volumes of data. Finally, the visualization pipeline is presented to review aspects of visualization methodology and visualization tool design, to conclude that the true potential of visualization emerge from the interaction of the user with the visualization model. The paper concludes establishing that the current processes of digital transformation will increase the need for visual analytics tools.

Color palettes are widely used by artists to de ne colors of artworks and explore color designs. In general, artists select the colors of a palette by following a set of rules, e.g. contrast or relative luminance. Existing interactive palette exploration tools explore palette spaces following limited constraints de ned as geometric con gurations in color space e.g. harmony rules on the color wheel. Palette search algorithms sample palettes from color relations learned from an input dataset, however they cannot provide interactive user edits and palette re nement. We introduce in this work a new versatile formulation enabling the creation of constraint-based interactive palette exploration systems. Our technical contribution is a graph-based palette representation, from which we de ne palette exploration as a minimization problem that can be solved e ciently and provide real-time feedback. Based on our formulation, we introduce two interactive palette exploration strategies: constrained palette exploration, and for the rst time, constrained palette interpolation. We demonstrate the performances of our approach on various application cases and evaluate how it helps users nding trade-o s between concurrent constraints.

Scientific visualization aims to present numerical values, or categorical information, in a way that enables the researcher to make an inference that furthers knowledge. Well-posed visualizations need to consider the characteristics of the data, the display environment, and human visual capacity. In the geosciences, visualizations are commonly applied to spatially varying continuous information or results. In this contribution we make use of a suite of newly written computer applications which enable spatially varying data to be displayed in a performant graphics environment. We present a comparison of color-mapping using illustrative color spaces (RGB, CIELAB). The interactive applications display the gradient paths through the chosen color spaces. This facilitates the creation of color-maps that accommodate the non-uniformity of human color perception, producing an image where genuine features are seen. We also take account of aspects of a dataset such as parameter uncertainty. For an illustrative case study using a seismic tomography result, we find that the use of RGB color-mapping can introduce non-linearities in the visualization, potentially leading to incorrect inference. Interpolation in CIELAB color space enables the creation of perceptually uniform linear gradients that match the underlying data, along with a simply computable metric for color difference, E. This color space assists accuracy and reproducibility of visualization results. Well-posed scientific visualization requires both "visual literacy" and "visual numeracy" on an equal footing with clearly written text. It is anticipated that this current work, with the included color-maps and software, will lead to wider usage of informed color-mapping in the geosciences.

Data graphics shape the way science is communicated, and the color schemes we employ can either faithfully represent or tacitly obscure the data a figure is intended to convey (Tufte, 1983). Tasteful use of color can make data graphics visually appealing and can draw viewers in, engaging the audience and encouraging further inspection of a figure. But wherever color is used to represent numerical values, its role transitions from a mere aesthetic nicety to carrying the responsibility of conveying data honestly and accurately. Yet, biases introduced by some common colormaps have gone widely unrecognized within the oceanographic community. Here, we describe the pitfalls of some commonly used colormaps, provide guidelines on effective, accurate colormap selection, and present a suite of perceptually uniform cmocean colormaps that have been designed for oceanographic data display. The cmocean package is available across multiple software programs, including MATLAB, Python, R, Generic Mapping Tools, and Ocean Data Viewer.