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Today, the objective of applying shadow theory to architectural drawing is usually to obtain one (or several) bitmap images. This a priori innocuous fact leads to vector images being conspicuous by their absence when lighting factors come into play during the modelling and parametric design of architecture and its environment. The present article sets out a methodology to calculate shadows by placing vector drawing not only at the heart of the process but also of the obtained results. We found that in today's context of university excellence, it is essential to apply knowledge, control, as well as possible editing and postproduction of the effects generated by rendering process lighting calculations. Such interventions are also generally useful and effective in our profession. [ABSTRACT FROM AUTHOR]

Various web-based image-editing tools and web-based collaborative tools exist in isolation. Research focusing to bridge the gap between these two domains is sparse. We respond to the above and develop prototype groupware for real-time collaborative editing of raster and vector images in a web browser. To better understand the requirements, we conduct a preliminary user study and establish communication and synchronization as key elements. The existing groupware for text documents or presentations handles the above through well-established techniques. However, those cannot be extended as it is for raster or vector graphics manipulation. To this end, we develop a document model that is maintained by a server and is delivered and synchronized to multiple clients. Our prototypical implementation is based on a scalable client–server architecture: using WebGL for interactive browser-based rendering and WebSocket connections to maintain synchronization. We evaluate our work qualitatively through a post-deployment user study for three different scenarios. For quantitative evaluation, we perform a thorough performance measure on both client and server side, thereby identifying design recommendations for future concurrent image-editing software(s). [ABSTRACT FROM AUTHOR]

In this study, the effect of dietary Spirulina (Arthrospira platensis) on color intensity, growth performance, total ammonia–nitrogen excretion (TAN), and profitability of common clownfish (Amphiprion ocellaris) was investigated. Three isoproteic (46%) and isolipidic (13%) diets were formulated as one control (C) and two different levels (15 and 30%) of Spirulina (SP15 and SP30) substituted for fish meal and cornmeal. Ten clownfish (initial body weight of 0.55 ± 0.04 g) per aquarium were distributed to nine glass aquariums (60 L) with three replicates. Fish were hand-fed a day to the satiation thrice. Clownfish were weighed in bulk, and the photographs were taken biweekly during the 12-week experiment. The determined regions of the images were standardized with a raster graphics editor and recorded the color parameters by considering both CMYK (cyan magenta yellow key) and RGB (red green blue) models. After the feeding trial, fish were starved for 3 days, and the total ammonia–nitrogen (TAN) was analyzed with the ammonia salicylate method on the next day for 12 h. At the end of the trial, the final mean weights (FMW) and specific growth rates (SGR) of SP15 (FMW: 1.95 ± 0.18 g, SGR: 1.75 ± 0.04%/day) and SP30 (FMW: 2.05 ± 0.14 g, SGR: 1.81 ± 0.05%/day) were significantly higher than the C (FMW: 1.68 ± 0.12 g, SGR: 1.58 ± 0.06%/day) group (P < 0.05). Both color models have proved the enhancement of the skin coloration (significant improvements were recorded in the colors, including red, green, magenta, and key, P < 0.05). Also, it was determined that the TAN was decreased with the increase of the Spirulina level (29.8, 22.9, and 17.6 mg-N/100 g fish/12 h for C, SP15, and SP30, respectively) in the diet (P < 0.05). However, a high level of Spirulina in the diet negatively affected profitability. Consequently, common clownfish's growth, color, and TAN improved with the dietary Spirulina. Considering that Spirulina is an expensive raw material, adding it into the diet at medium levels (15%) is recommended. [ABSTRACT FROM AUTHOR]

The presented study addresses the characterization of nanometer sized defects acting as damage precursors in nanosecond laser pulse duration regime. Two approaches are used to extract distributions of localized damage precursors, namely, damage probability and damage density measurements. Testing is performed on uncoated and SiO2 monolayer film deposited fused silica substrate exposed with pulsed UV irradiation (355 nm, 4.8 ns). Then, a direct comparison of damage precursor ensembles obtained from both methods is carried out. Our analysis indicates apparent differences between both methods that are discussed in detail. Contamination by ablation products is identified as one of the key factors that influence damage density measurements. [ABSTRACT FROM AUTHOR]

In this paper, we present two approaches for recording a quasi-hologram on the steel surface by femtosecond laser pulses. The recording process is done by rotating the polarization of the laser beam by a half-wave plate or a spatial light modulator (SLM), so we can control the spatial orientation of the formed laser-induced periodic surface structures (LIPSS). Two different approaches are shown, which use vector and bitmap images to record the hologram. For the first time to our knowledge, we managed to record a hologram of a bitmap image by continuously adjusting the laser beam polarization by SLM during scanning. The developed method can substantially improve hologram recording technology by eliminating complex processing procedures, which can lead to increasing the fabrication speed and reducing the cost. [ABSTRACT FROM AUTHOR]

Forty years ago, the first General Purpose Raster Graphics Processor made the transition from research project to commercial product. This is the story of the creation of a new graphics system and the startup company that produced it in the early days of raster computer graphics. [ABSTRACT FROM AUTHOR]

Glaciers depicted on old maps reveal their historical extents, before the advent of aerial and satellite remote sensing. Digital glacier inventories produced from these maps can be employed in assessments of centennial-scale glacier change. This study reconstructs the ~1899 (covering the period 1882–1916) glacier extent in Nordland, northern Norway, from historical gradteigskart maps, with an emphasis on examining the accuracy of the mapped glaciers. Glacier outlines were digitised from georectified scans of the analogue maps in a raster graphics editor and were subsequently inventoried in a GIS. The accuracy of the historical glacier extent was established from written descriptions and landscape photographs created during the original field surveys, and further validated against independent glacier outlines of (1) the maximum Little Ice Age extent derived from geomorphological evidence, and (2) the 1945 extent derived from vertical aerial photographs. An overall uncertainty of ±17% is associated with our inventory. Nordland's glaciers covered an area of 1712 ± 291 km2 in 1899. By 2000, total ice cover had decreased by 47% (807 ± 137 km2) at a rate of 6% 10 a−1 (80 ± 14 km2 10 a−1). The approach presented here may serve as a blueprint for future studies intending to derive glacier inventories from historical maps. [ABSTRACT FROM AUTHOR]

We report the preliminary results of a meta-analysis conducted to examine possible biases in the uncertainty values published in papers by ATLAS and CMS experiments. We have performed this analysis using two independent techniques: a vectoral analysis of the vector graphics files and a bitmap analysis of the raster graphic files of the exclusion plots from various physics searches. In both procedures, the aim is to compute the percentages of the data points scattered within 1σ and 2σ bands of the plots and verify whether the measured percentages agree with statistical norms, assuming unbiased estimations of the uncertainties. [ABSTRACT FROM AUTHOR]

The plastic forming properties of metal depend on the nature of the metal and on the deformation conditions. However, in the process of grating mechanical scribing, the flow of materials, the distribution of stress and strain fields, and the tool loading can be hardly detected and controlled. In order to obtain a better groove shape and ensure the quality of the grating geometry, the metal flow inside the material during the scratching process was studied. The equivalent strain map, stress distribution, and metal flow rate of the scratching process can be clearly obtained from the simulation results of the grating scribe, and the flow law of the metal material can be grasped. By analyzing the equivalent strain map and stress distribution of the grating scribing process, the force distribution and size of the aluminum film are obtained, which is reflected in the stress of each side of the extended pyramid knife and each blade. To provide the theoretical basis and test data for the design of diamond-like tool design and its process, so as to improve the design quality and efficiency of the tool and provide scientific basis for the orientation and development of such diamond scribe tool. [ABSTRACT FROM AUTHOR]

Piezoelectric actuators are widely used in scanning platforms of scanning probe microscopes (SPMs). However, the hysteresis of piezoelectric actuators reduces positioning accuracy and results in distorted SPM images. When regular raster scanning of SPM starts, the piezoelectric actuators move repeatedly at the same scanning range and frequency once the scanning parameters are set. In this study, a practical and simple mathematical model derived from experimental phenomenon, which is the combination of sinusoidal and linear functions, was proposed to describe the hysteresis behavior of piezoelectric actuators with repeated scanning. The model parameter was calculated from the coordinates of matched feature points in the trace and retrace images of ordinary sample obtained with an atomic force microscope (AFM). Experimental results show that the hysteresis of the scanned images is decreased from 107.46 pixels to 2.50 pixels after correction, with a width of 800 pixels. Hysteresis in other scanned images with different scanning frequencies and ranges was also corrected effectively using this model. The proposed model can be used to correct the hysteresis of AFM images without using any expensive displacement sensors or standard samples. The model is suitable and easy to be integrated into the scanning program of AFM without requiring hardware modifications. [ABSTRACT FROM AUTHOR]

Bitmap-based indexes are known to be the most effective indexing method for retrieving and answering selective queries in a read-only environment. Various types of encoding bitmap indexes significantly improve query time efficiency by utilizing fast Boolean operations directly on the index before retrieving the raw data. In particular, the dual bitmap index improves the performance of equality queries in terms of the space vs. time trade-off. However, the performance of range queries is unsatisfactory. In this paper, an optimizing algorithm is proposed to improve the range query processing for the dual bitmap index. The results of the experiment conducted show that the proposed algorithm, called Dual-simRQ, reduces the number of bitmap vectors scanned and the Boolean operations performed, which impacts the overall performance for range query processing. [ABSTRACT FROM AUTHOR]

Highlights • Two joint image compression and encryption schemes based on JPEG are proposed. • A trade-off between encryption power and compression ability is considered. • The first encryption scheme has better compression performance. • The second encryption scheme has stronger security level. Abstract Joint image encryption and compression schemes have shown their great potential values in protecting compressed images. To achieve the protection, a trade-off between encryption power and compression ability needs to be considered. In this paper, we propose two new joint encryption and compression schemes, where one scheme emphasizes compression performance, another highlights protection performance. For a given plain-image, we first raster scan it into non-overlapping 16 × 16 blocks, then apply various encryption techniques to it. In the first scheme, encryption operations are conducted at the transformation stage and quantization stage of JPEG. As for the second scheme, we add the run/size and value (RSV) pairs' shuffling operation at JPEG's entropy coding stage after first scheme's encryption operations. Performance evaluations using various criteria are conducted to show that the first scheme has better compression efficiency, while the second scheme has better defense ability against the statistical attack. [ABSTRACT FROM AUTHOR]

Novel fault leveling techniques based on address remapping (AR) are proposed in this paper. We can change the logical-to-physical address mapping of the page buffer such that faulty cells within a flash page can be evenly distributed into different codewords. Therefore, the adopted ECC scheme can correct them effectively. Based on the production test or on-line BIST results, the fault bitmap can be used for executing the heuristic fault leveling analysis (FLA) algorithm and evaluating control words used to steer fault leveling. A new page buffer architecture suitable for address remapping is also proposed. According to experimental results, repair rate, yield, and reliability can be improved significantly with negligible hardware overhead. [ABSTRACT FROM AUTHOR]

Fidelity has been a critical concern of researchers throughout the history of driving simulation. Understanding the limits of a driving simulation system is a prerequisite for conducting valid driving simulator studies. This paper proposes a novel and interdisciplinary methodology to ensure validity of studies using driving simulators (primarily for traffic control devices and other object detection tasks) based on the visual limits of human sensory and perceptual capabilities, and the characteristics of raster graphics. This methodology decomposes the perceptual issues of a stimulus into perceptual issues of different visual properties like luminance, hue, or text of the stimulus. By systematically analyzing the mechanism of human vision in driving simulators, the perceptual principle is proposed to ensure perceivable visual details in human-in-the-loop driving simulation systems. Additionally, the graphic principle is proposed to ensure perceivable features of a target object in the virtual driving environment. Both principles quantify the minimum requirements of visual fidelity with two measurements: angular resolution and matrix dimensions. The enriched results from existing pertinent studies are analyzed and organized to yield support of both principles. This research focuses on the minimum requirements for four factors; namely the visual acuity of drivers, the specifications of display systems, the configurations of graphics systems, and the design of virtual scenarios, as well as the relationship among all these factors to assess the visual fidelity in driving simulation systems. Within the realm of human perception, this work can provide criteria for proper design, calibration, and usage of driving simulators. [ABSTRACT FROM AUTHOR]

The paper proposes a novel method for detecting indicators of image forgery by locating grid alignment abnormalities in JPEG compressed image bitmaps. The method evaluates multiple grid positions with respect to a fitting function, and areas of lower contribution are identified as grid discontinuities and possibly tampered areas. An image segmentation step is introduced to differentiate between discontinuities produced by tampering and those that are attributed to image content, making the output maps easier to interpret by suppressing non-relevant activations. Our evaluations, on both synthetically produced datasets and real world tampering cases against seven methods from the literature, highlight the effectiveness of the proposed method in its ability to produce output maps that are clear and readable, and which can achieve successful detections on cases where other algorithms fail. [ABSTRACT FROM AUTHOR]

In this paper, we present techniques for offsetting spherical curves represented in vector or raster form. Such techniques allow us to efficiently determine and visualize the region within a given distance of a spherical curve. Our methods additionally support multiresolution representations of the underlying data, allowing the initial coarse offsets to be provided quickly, which may then be iteratively refined to the correct result. An example application of offsetting is also specifically explored in the form of improving the performance of inside/outside tests in the vector case. [ABSTRACT FROM AUTHOR]

Computer architectures have evolved into parallel and heterogeneous systems with multi-core CPUs, many-core GPUs, and vector instructions. Meanwhile, advances in data collection technologies have led to a rapid increase in the spatial and temporal resolution of geographic data. Efficiently dealing with large volumes of geographic data demands, now more than ever, an effective use of modern parallel computers. However, parallel programming is distinctly more challenging than writing sequential scripts. Moreover, parallelism is not the only issue; data locality is critical, too. This work addresses the issues of data escalation and parallel transition using a compiler approach to map algebra. More specifically, we design and implement a framework that uses compiler techniques to automatically speed up raster spatial analysis. In this way, users simply write sequential map algebra scripts in Python, which are translated into a graph where optimizations are applied. Then the scripts are parallelized, reordered for locality, and executed on OpenCL devices such as multi-core CPUs and GPUs. The novelty of our approach resides in the efficient organization of the execution, which we achieve via compilation. Unlike interpreters, our framework reorders the raster operations to maximize data reuse and minimize memory movements. The reordering occurs at two hierarchical levels and is controlled by a scheduler and a fusion technique. This strategy targets data locality, which, as we show, is key to the performance of raster spatial analysis. The experiments report speed-ups of one to two orders of magnitude compared to traditional interpreters. [ABSTRACT FROM AUTHOR]

Raster map viewers can be used by various entities, including public administration units. They are used in particular when there is no economic justification for creating extended and comprehensive mapping services, or when there is a need to quickly publish the given map. These viewers can be made using one of many available components. However, not all of them are optimal for such applications. Selected raster map viewers may be inefficient, which may make it difficult or even impossible to view the map. The aim of the present work was to conduct a comparative analysis of the performance of selected raster map viewers. The prototype applications were used to test the implementation of selected designing tools. The efficiency measurement was made using tools for test automation. The value of the ESSCORE (Estimated Speed Score) synthetic performance meta-index has been determined. It has been shown that the application created with the use of the ImageViewer component (jQuery JavaScript) was objectively the best of the tests tested for the presentation of raster graphics (according to the adopted testing scheme). [ABSTRACT FROM AUTHOR]

An MeV-SIMS microprobe has been constructed based on primary beam collimation by a conical glass capillary. Molecular surface mapping is obtained by raster scanning of the sample with a piezo-driven XY stage. The angular divergence of the collimated beam is smaller than 0.3 mrad, which allows a relatively large distance between capillary exit and sample without a significant loss in lateral resolution. With a capillary of 5 μm outlet diameter a lateral resolution of approximately 10 μm has been observed at a working distance of 50 mm. Capillary collimation can be obtained in a very simple and inexpensive fashion and is virtually independent of the used beam particle properties over a large range of ion mass and energy. [ABSTRACT FROM AUTHOR]

Matrix-assisted laser desorption/ionization-mass spectrometry imaging (MALDI-MSI) has been employed to rapidly screen longitudinally sectioned drug user hair samples for cocaine and its metabolites using continuous raster imaging. Optimization of the spatial resolution and raster speed were performed on intact cocaine contaminated hair samples. The optimized settings (100 × 150 μm at 0.24 mm/s) were subsequently used to examine longitudinally sectioned drug user hair samples. The MALDI-MS/MS images showed the distribution of the most abundant cocaine product ion at m/z 182. Using the optimized settings, multiple hair samples obtained from two users were analyzed in approximately 3 h: six times faster than the standard spot-to-spot acquisition method. Quantitation was achieved using longitudinally sectioned control hair samples sprayed with a cocaine dilution series. A multiple reaction monitoring (MRM) experiment was also performed using the 'dynamic pixel' imaging method to screen for cocaine and a range of its metabolites, in order to differentiate between contaminated hairs and drug users. Cocaine, benzoylecgonine, and cocaethylene were detectable, in agreement with analyses carried out using the standard LC-MS/MS method. [ABSTRACT FROM AUTHOR]

We consider two NP-hard open dimension nesting problems for which a set of items has to be packed without overlapping into a two-dimensional bin in order to minimize one or both dimensions of this bin. These problems are faced by real-life applications, such as textile, footwear and automotive industries. Therefore, there is a need for specialized systems to help in a decision making process. Bearing this in mind, we derive new concepts as the no-fit raster, which can be used to check overlapping between any two-dimensional generic-shaped items. We also use a biased random key genetic algorithm to determine the sequence in which items are packed. Once the sequence of items is determined, we propose two heuristics based on bottom-left moves and the no-fit raster concept, which are in turn used to arrange these items into the given bin observing the objective criteria. As far as we know, the problem with two-open dimensions is being solved for the first time in the context of nesting problems and we present the first whole quadratic model for this problem. Computational experiments conducted on benchmark instances from the literature (some from the textile industry and others including circles, convex, and non-convex polygons) show the competitiveness of the approaches developed as they were able to calculate the best results for 74.14% of the instances. It can be observed that these results show new directions in terms of solving nesting problems whereby approaches can be coupled in existing intelligent systems to support decision makers in this field. [ABSTRACT FROM AUTHOR]

In BitTorrent network, the bitmap is used to indicate the state of data blocks of file owned by a peer. Before the downloading of the file starts, the file provider first sends its corresponding bitmap to the requester to show which data blocks it owns. This provides the possibility for hiding the identity information in the bitmap and exchanging the identity information secretly. In this paper, we propose a bitmap-based steganographic handshake approach and implement a prototype system based on the BitTorrent network. In our prototype system, the network can operate normally. More importantly, hidden peers successfully exchange their identity information and accurately identify the other hidden peers without being detected by the regular peers. © 2017 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc. [ABSTRACT FROM AUTHOR]

Due to the rapid development of the Internet of Things (IoT), many feasible deployments of sensor monitoring networks have been made to capture the events in physical world, such as human diseases, weather disasters and traffic accidents, which generate large-scale temporal data. Generally, the certain time interval that results in the highest incidence of a severe event has significance for society. For example, there exists an interval that covers the maximum number of people who have the same unusual symptoms, and knowing this interval can help doctors to locate the reason behind this phenomenon. As far as we know, there is no approach available for solving this problem efficiently. In this paper, we propose the Bitmap-based Maximum Range Counting (BMRC) approach for temporal data generated in sensor monitoring networks. Since sensor nodes can update their temporal data at high frequency, we present a scalable strategy to support the real-time insert and delete operations. The experimental results show that the BMRC outperforms the baseline algorithm in terms of efficiency. [ABSTRACT FROM AUTHOR]

Among cartographic works, three-dimensional panoramas should be marked out as a special kind of map, which are characterised by visual modes of representing objects in space. The main principles of the creation of both hand-painted and automated maps vector and raster graphics software (Corel Draw and Adobe Photoshop) are considered in the paper. The use of modern information technologies has several advantages over traditional mapping. [ABSTRACT FROM AUTHOR]

Intuition from our everyday lives gives rise to the belief that information exchanged between remote parties is carried by physical particles. Surprisingly, in a recent theoretical study [Salih H, Li ZH, Al-Amri M, Zubairy MS (2013) Phys Rev Lett 110:170502], quantum mechanics was found to allow for communication, even without the actual transmission of physical particles. From the viewpoint of communication, this mystery stems from a (nonintuitive) fundamental concept in quantum mechanics—wave-particle duality. All particles can be described fully by wave functions. To determine whether light appears in a channel, one refers to the amplitude of its wave function. However, in counterfactual communication, information is carried by the phase part of the wave function. Using a single-photon source, we experimentally demonstrate the counterfactual communication and successfully transfer a monochrome bitmap from one location to another by using a nested version of the quantum Zeno effect. [ABSTRACT FROM AUTHOR]

The field of computational cognitive neuroscience (CCN) builds and tests neurobiologically detailed computational models that account for both behavioral and neuroscience data. This article leverages a key advantage of CCN–namely, that it should be possible to interface different CCN models in a plug-and-play fashion–to produce a new and biologically detailed model of perceptual category learning. The new model was created from two existing CCN models: the HMAX model of visual object processing and the COVIS model of category learning. Using bitmap images as inputs and by adjusting only a couple of learning-rate parameters, the new HMAX/COVIS model provides impressively good fits to human category-learning data from two qualitatively different experiments that used different types of category structures and different types of visual stimuli. Overall, the model provides a comprehensive neural and behavioral account of basal ganglia-mediated learning. [ABSTRACT FROM AUTHOR]

Geospatial transformations in the form of reprojection calculations for large datasets can be computationally intensive; as such, finding better, less expensive ways of achieving these computations is desired. In this paper, we report our efforts in developing a Compute Unified Device Architecture (CUDA)-based parallel algorithm to perform map reprojections for raster datasets on personal computers using Graphics Processing Units (GPUs). This algorithm has two unique features: a) an output-space-based parallel processing strategy to handle transformations more rigorously, and b) a chunk-based data decomposition method for projected space in conjunction with an on-the-fly data retrieval mechanism to avoid memory overflow. To demonstrate the performance of our CUDA-based map reprojection approaches, we have conducted tests between this method and the traditional serial version using the Central Processing Unit (CPU). The results show that speedup ratios range from 10 times to 100 times in all test scenarios. The lessons learned from the tests are summarized. [ABSTRACT FROM AUTHOR]

Vector and raster are two types of spatial data structures used in a geographic information system (GIS). With the development of GIS and remote sensing (RS) technologies, how to rapidly convert raster to vector data and establish topological relations among vectorized polygons is becoming a bottleneck in data integration between GIS and RS. Based on the previous work, an improved vectorization method is proposed to vectorize classified RS raster data quickly and automatically establish topological relations. In accordance with the connection information of arcs and nodes and both-sides polygonal attributes of arcs, the next arc can be searched directly by attribute matching when constructing polygons, thereby improving search efficiency. Moreover, our method addressed the problems of self-intersecting polygons, shared-boundary, and multi-nested islands and gave corresponding solutions, which can establish the topological relations of an entire image quickly. Two experiments, one for comparison between before and after vectorization of two different classified RS raster maps, and the other for comparison with several methods, are carried out to test the accuracy and efficiency of our method. Results show that the method solves the self-intersecting polygons, shared-boundary, and multi-nested islands problems. In addition, its vectorization speed is more than double that of commercial software ArcGIS, and the advantage of our method becomes more obvious as the number of polygons increases. Thus, our method can vectorize large and complex classified RS raster data with sufficient efficiency for practical use and establish topological relations among vectorized polygons. [ABSTRACT FROM AUTHOR]

Summary The graphical fragment assembly (GFA) formats are emerging standard formats for the representation of sequence graphs. Although GFA 1 was primarily targeting assembly graphs, the newer GFA 2 format introduces several features, which makes it suitable for representing other kinds of information, such as scaffolding graphs, variation graphs, alignment graphs and colored metagenomic graphs. Here, we present GfaViz , an interactive graphical tool for the visualization of sequence graphs in GFA format. The software supports all new features of GFA 2 and introduces conventions for their visualization. The user can choose between two different layouts and multiple styles for representing single elements or groups. All customizations can be stored in custom tags of the GFA format itself, without requiring external configuration files. Stylesheets are supported for storing standard configuration options for groups of files. The visualizations can be exported to raster and vector graphics formats. A command line interface allows for batch generation of images. Availability and implementation GfaViz is available at https://github.com/ggonnella/gfaviz Supplementary information Supplementary data are available at Bioinformatics online. [ABSTRACT FROM AUTHOR]

Point alignment is an important topic in computer vision. In order to implement cross-stitch embroidery in an automatic way, the grid points in a raster like pattern are desired to be recognized at first. In this paper, we design an algorithm to align the grid points in a raster like pattern in case of checkerboard pattern, and the proposed method was used to recognize the weave holes in a cross-stitch pattern. The method implemented in four steps. First, vertices on the boundary were extracted via removing the inner points. Next, the four corner points were detected in the extracted boundary points. Then the left-lower and left-upper points were positioned. Finally, the points alignment was implemented starting at the left-lower point from the bottom to top, left to right. The comparison experiments demonstrated that our method is robust to geometrical distortion and pose change. The method was applied to align the weave holes in a cross-stitch pattern. The results showed that the proposed method addressed its potential application to the machine weave of the cross-stitch. [ABSTRACT FROM AUTHOR]

The problem of caching shortest paths has been widely studied. All of existing methods that address this problem assume that the condition of road networks does not change with time. In this paper, we study how to refresh a cache when one edge of the underlying road network (graph) changes. A bitmap-based cache structure is proposed to store and give access to shortest paths. In the following, algorithms are developed to detect shortest paths that are affected by the change of edge. After detecting affected paths, several heuristic-based refreshment strategies are proposed to update the cache. We have conducted a series of experiments to compare the performance of proposed strategies. It shows that replacing affected shortest paths with new paths whose benefit values are the largest should be applied in the shortest path caching applications such as navigation and map services. [ABSTRACT FROM AUTHOR]

This paper presents a method for automatically constructing irregular floor plans. Given image patterns, the program produces a variety of layouts that satisfy users' geometric and topological requirements. The program extracts irregular regions from images via statistical region merging. It employs subgraph matching and simulated annealing to construct topologically feasible layouts. Methods for measuring similarities between the desired templates and irregular rooms are also reported. Applications using raster images and vector graphics are tested. Both applications generate feasible floor plans whose appearances resemble the input patterns. The results indicate that layout automation is valid without an orthogonal framework in the plane. Irregular layout synthesis allows architects to instantly implement visual preferences in early design stages. [ABSTRACT FROM AUTHOR]

Bitmap indexes are commonly used in data warehousing applications such as on-line analytic processing (OLAP). Storing the bitmaps in compressed form has been shown to be effective not only for low cardinality attributes, as conventional wisdom would suggest, but also for high cardinality attributes. Compressed bitmap indexes, such as Byte - aligned Bitmap Compression (BBC), Word - Aligned Hybrid (WAH) and several of their variants have been shown to be efficient in terms of both time and space, compared to traditional database indexes. In this paper, we propose a new technique for compressed bitmap indexing, called Super Byte - aligned Hybrid (SBH) bitmap compression, which improves upon the current state-of-the-art compression schemes. In our empirical evaluation, the query processing time of SBH was about five times faster than that of WAH, while the size of its compressed bitmap indexes was retained nearly close to that of BBC. [ABSTRACT FROM AUTHOR]

Big data are visually cluttered by overlapping data points. Rather than removing, reducing or reformulating overlap, we propose a simple, effective and powerful technique for density cluster generation and visualization, where point marker (graphical symbol of a data point) overlap is exploited in an additive fashion in order to obtain bitmap data summaries in which clusters can be identified visually, aided by automatically generated contour lines. In the proposed method, the plotting area is a bitmap and the marker is a shape of more than one pixel. As the markers overlap, the red, green and blue (RGB) colour values of pixels in the shared region are added. Thus, a pixel of a 24-bit RGB bitmap can code up to 224 (over 1.6 million) overlaps. A higher number of overlaps at the same location makes the colour of this area identical, which can be identified by the naked eye. A bitmap is a matrix of colour values that can be represented as integers. The proposed method updates this matrix while adding new points. Thus, this matrix can be considered as an up-to-time knowledge unit of processed data. Results show cluster generation, cluster identification, missing and out-of-range data visualization, and outlier detection capability of the newly proposed method. [ABSTRACT FROM AUTHOR]

The choice of the proper resolution in landslide susceptibility mapping is a worth considering issue. If, on the one hand, a coarse spatial resolution may describe the terrain morphologic properties with low accuracy, on the other hand, at very fine resolutions, some of the DEM-derived morphometric factors may hold an excess of details. Moreover, the landslide inventory maps are represented throughout geospatial vector data structure, therefore a conversion procedure vector-to-raster is required. This work investigates the effects of raster resolution on the susceptibility mapping in conjunction with the use of different algorithms of vector-raster conversion. The Artificial Neural Network technique is used to carry out such analyses on two Sicilian basins. Seven resolutions and three conversion algorithms are investigated. Results indicate that the finest resolutions do not lead to the highest model performances, whereas the algorithm of conversion data may significantly affect the ANN training procedure at coarse resolutions. [ABSTRACT FROM AUTHOR]

Virtualization provides the function of saving the entire status of the execution environment of a running virtual machine (VM), which makes checkpointing flexible and practical for HPC servers or data center servers. However, the system-level checkpointing needs to save a large number of data to the disk. Moreover, the overhead grows linearly with the increasing size of virtual machine memory, which leads to disk I/O consumption disaster along with poor system scalability. To target this, we propose a novel fast VM checkpointing approach, named Fast Incremental checkpoinTing with Delta memOry Compression (FITDOC). By studying the run-time memory characteristics of different workloads, FITDOC counts the dirty pages in a fine-granularity manner (i.e., the number of 8 bytes), instead of in the conventional method (i.e., the number of pages). FITDOC utilises a dirty page logging mechanism to record the dirty pages. Accordingly, a delta memory compression mechanism is implemented to eliminate redundant memory data in checkpointing files. To locate the dirty data in dirty pages, FITDOC utilizes two mechanisms: by analyzing the distribution characteristics of dirty pages in the dirty bitmap, we propose a fast dirty bitmap scanning method to locate the dirty pages, and take a multi-threading data comparison mechanism to locate the real dirty data in one page. The experimental results show that compared with Xen's default system-level checkpointing algorithm, FITDOC can on average reduce checkpointing time 70.54 % with a 1 GB memory size and achieve better improvement for VMs with larger memory configurations. FITDOC can reduce the size of checkpointing data 52.88 % on average compared with Remus's incremental solution, which is in page granularity. Compared with the default dirty bitmap scanning method in Xen, the scanning time of FITDOC is decreased by 91.13 % on average. [ABSTRACT FROM AUTHOR]

Given a grid of cells each having an associated cost value, a raster version of the least-cost path problem seeks a sequence of cells connecting two specified cells such that its total accumulated cost is minimized. Identifying least-cost paths is one of the most basic functions of raster-based geographic information systems. Existing algorithms are useful if the path width is assumed to be zero or negligible compared to the cell size. This assumption, however, may not be valid in many real-world applications ranging from wildlife corridor planning to highway alignment. This paper presents a method to solve a raster-based least-cost path problem whose solution is a path having a specified width in terms of Euclidean distance (rather than by number of cells). Assuming that all cell values are positive, it does so by transforming the given grid into a graph such that each node represents a neighborhood of a certain form determined by the specified path width, and each arc represents a possible transition from one neighborhood to another. An existing shortest path algorithm is then applied to the graph. This method is highly efficient, as the number of nodes in the transformed graph is not more than the number of cells in the given grid and decreases with the specified path width. However, a shortcoming of this method is the possibility of generating a self-intersecting path which occurs only when the given grid has an extremely skewed distribution of cost values. [ABSTRACT FROM PUBLISHER]

Estimating the cardinality of data streams over a sliding window is an important problem in many applications, such as network traffic monitoring, web access log analysis and database. The problem becomes more difficult in large-scale data streams when time and space complexity is taken into account. In this paper, we present a novel randomized data structure to address the problem. The significant contributions are as follows: (1) A space-efficient counter vector sketch (CVS) are proposed, which extends the well-known bitmap sketch to sliding window settings. (2) Based on the CVS, a random update mechanism is introduced, whereby a small fixed number of entries are randomly chosen from CVS in a step and then updated. This means that the update procedure just costs constant time. (3) Furthermore, estimating cardinality by CVS just needs one-pass scan of the data. (4) Finally, a theoretical analysis is given to show the accuracy of CVS-based estimators. Our comprehensive experiments confirm that the CVS-based schema attains high accuracy, and demonstate its time efficiency in comparison with the Timestamp Vector (TSV) and the auxiliary indexing method. [ABSTRACT FROM AUTHOR]

In raster scanning applications of atomic force microscopies, precisely tracking periodic triangular trajectories is the major objective of nanopositioning stages. Considering the fact of periodic operations, the repetitive control technique becomes promising and has been recently developed to reduce tracking errors. In our new experiments, it is found that, with triangular reference input, the hysteresis nonlinearity mainly affects the system at the odd harmonics of the input signal. In this sense, an odd-harmonic repetitive control (ORC) strategy is proposed to handle the hysteresis nonlinearity, with the hysteresis treated as the odd-harmonic periodic disturbance. Therefore, it avoids the modeling and inverting of the complex hysteresis nonlinearity. Another benefit of the developed ORC strategy is that it can also account for the tracking errors caused by the linear dynamics effect. To verify the effectiveness of the ORC strategy, real-time experiments are performed on a custom-built piezo-actuated nanopositioning stage. Experimental results show that the developed ORC strategy achieves precise tracking of 1562.5-Hz triangular trajectory with the hysteresis nonlinearity mitigated to a negligible level, which demonstrates the feasibility and effectiveness of the developed ORC strategy on hysteresis compensation during high-speed raster scanning. [ABSTRACT FROM AUTHOR]

In real-time collaborative graphical editing systems, bitmap-based graphical editing systems are particularly special and practically useful ones, and Do and Undo/Redo operations are intricate problems in this field. However, existing researches on graphical editing systems are quite scanty. In this paper, based on Multi-version strategy, we propose a new approach to solve the Do and Undo/Redo consistency maintenance problems with due consideration of three possible cases: all-causal, all-independent and causal-independent-mixed operations. Compared with previous collaborative algorithms, the algorithms proposed in this paper support Do and Undo/Redo operations without requiring additional space. In addition, two example analyses are also given to prove the algorithms' effectiveness separately. Furthermore, the time complexity of the two algorithms is both O(n). Finally, a system prototype called bitmap-based Co-Graphical Editor is implemented to verify them realistically. [ABSTRACT FROM AUTHOR]

We propose here an efficient algorithm for high-level vectorization of scanned images of mechanical engineering drawings. The algorithm is marked by several novel features, which merit its superiority over the existing techniques. After preprocessing and necessary refinement of junction points in the image skeleton, it first extracts the graphic primitives, such as lines, circles, and arcs, based on certain digital geometric properties of straightness and circularity in the discrete domain. The primitives are classified into different types with all associated details based on fast and efficient geometric analysis. The vector set is succinctly reduced by such classification in tandem with further consolidation to make out meaningful objects like rectangles and annuli, together with hatching information. Exhaustive testing shows the efficiency of the algorithm and also its robustness and stability toward any affine transformation and injected noise. Easy reconstruction to scalable vector graphics demonstrates its readiness and usability as a state-of-the-art solution. [ABSTRACT FROM AUTHOR]

The virtual globe is the default visualization for Digital Earth applications, but it can only show one half of the Earth. This article introduces user-adjustable, on-the-fly projection of georeferenced raster images for web mapping and web GIS applications. This technique allows users to center a map on arbitrary locations, while still seeing the entire Earth surface. Modern web mapping libraries can apply map projection transformations to vector data in the browser, but they do not currently support the projection of raster images at interactive frame rates. We use the cross-platform WebGL (Web Graphics Library) graphics pipeline for hardware-accelerated projection of raster data in web browsers. Two algorithmic techniques – inverse per-fragment projection, and combined forward per-triangle and inverse per-fragment projection – for georeferenced raster imagery are documented. The resulting raster maps combine the ease of use and flexibility of interactive virtual globes with the ability to show the entire Earth. The adjustable projection of raster imagery allows users to observe global phenomena that are difficult to visualize on virtual globes or traditional maps with static projections. [ABSTRACT FROM PUBLISHER]

Block Truncation Coding (BTC) image compression technique is capable of extraordinary computational efficiency for high-framerate configurations under the trend of high image resolution. However, the recent development such as the Dot-Diffused BTC (DDBTC) method still encounters various challenges of visual artifacts, including impulsive noise, false contours and blocking effects. In this study, a new method, the Near-Aperiodic DDBTC (NADDBTC) technique, is proposed to analyze the tradeoff and balance between computational efficiency and visual artifacts. It is mainly because of the quantization levels and the co-optimized Class Matrix (CM) and Diffused Matrix (DM) during image compression procedure. In addition, the tiling method for bitmap generation is optimized for aperiodic compressed results. Experimental results show that this method is capable of excellent image quality and visual perception, as well as processing efficiency, at a level similar to the DDBTC technique by taking advantage of parallel processing in dot diffusion. [ABSTRACT FROM AUTHOR]