A method to improve two-dimensional layout

A graphics problem of great interest to industry is that of optimum two-dimensional layout. An operator is given a number of rectangular sheets and an order for a specified number of certain types of two-dimensional shapes. The objective is to cut the shapes out of the sheets in such a way as to minimize the amount of waste produced. A system is proposed where a tentative solution is automatically generated and then interactive improvements are allowed by a conversational display unit. The design criteria, the structure and the main features of the system are illustrated.     

Interactive display of large NURBS models

We present algorithms for interactive rendering of large-scale NURBS models. The algorithms convert the NURBS surfaces to Bezier surfaces, tessellate each Bezier surface into triangles, and render them using the triangle-rendering capabilities common to current graphics systems. We present algorithms for computing tight bounds on surface properties in order to generate high quality tessellation of Bezier surfaces. We introduce enhanced visibility determination techniques and present methods to make efficient use of coherence between successive frames. In addition, we also discuss issues in parallelization of these techniques. The algorithm also avoids polygonization anomalies like cracks. Our algorithms work well in practice and, on high-end graphics systems, are able to display models described using thousands of Bezier surfaces at interactive frame rates     

Windows下多幅大尺寸位图的显示与浏览

本文介绍了在Ｗｉｎｄｏｗｓ环境下,利用Ｗｉｎｄｏｗｓ的ＡＰＩ函数,显示与游览多幅大尺寸彩色位图的几种方法。通过比较几个常用图象函数的运行结果,提出了提高程序运行速度的方法,并给出相关的源程序。     

Interactive visualization of large state spaces

Insight into the global structure of a state space is of great help in the analysis of the underlying process. We advocate the use of visualization for this purpose and present a method to visualize the structure of very large state spaces with millions of nodes. The method uses a clustering based on an equivalence relation to obtain a simplified representation, which is used as a backbone for the display of the entire state space. With this visualization we are able to answer questions about the global structure of a state space that cannot easily be answered by conventional methods. We show this by presenting a number of visualizations of real-world protocols .     

Interactive display techniques for the Tektronix 4027 colour terminal

Various interactive display techniques implemented on a Tektronix 4027 colour terminal are described. The facilities of the device are outlined and techniques enhancing man machine communication in a caad context are explored. The techniques are classified into three groups - data input, command selection and output representation     

Incorporating multiple distance spaces in optimum-path forest classification to improve feedback-based learning

In content-based image retrieval (CBIR) using feedback-based learning, the user marks the relevance of returned images and the system learns how to return more relevant images in a next iteration. In this learning process, image comparison may be based on distinct distance spaces due to multiple visual content representations. This work improves the retrieval process by incorporating multiple distance spaces in a recent method based on optimum-path forest (OPF) classification. For a given training set with relevant and irrelevant images, an optimization algorithm finds the best distance function to compare images as a combination of their distances according to different representations. Two optimization techniques are evaluated: a multi-scale parameter search (MSPS), never used before for CBIR, and a genetic programming (GP) algorithm. The combined distance function is used to project an OPF classifier and to rank images classified as relevant for the next iteration. The ranking process takes into account relevant and irrelevant representatives, previously found by the OPF classifier. Experiments show the advantages in effectiveness of the proposed approach with both optimization techniques over the same approach with single distance space and over another state-of-the-art method based on multiple distance spaces.     

A large screen matrix display using an array of ac plasma display panels

A direct-view large-screen matrix type display using an array of ac plasma display modules has been developed. Its resolution can reach 160 lines m^?1 and 230 lines m^?1: the screen area being expanded according to the user's requirements. It can be used in the areas of alphanumerics and graphics. This paper describes its structure, drive circuit, and some design considerations.     

Automatic mining of source code repositories to improve bug finding techniques

We describe a method to use the source code change history of a software project to drive and help to refine the search for bugs. Based on the data retrieved from the source code repository, we implement a static source code checker that searches for a commonly fixed bug and uses information automatically mined from the source code repository to refine its results. By applying our tool, we have identified a total of 178 warnings that are likely bugs in the Apache Web server source code and a total of 546 warnings that are likely bugs in Wine, an open-source implementation of the Windows API. We show that our technique is more effective than the same static analysis that does not use historical data from the source code repository.     

Using OVA modeling to improve classification performance for large datasets

One-Versus-All (OVA) classification is a classifier construction method where a k-class prediction task is decomposed into k 2-class sub-problems. One base model is constructed for each sub-problem and the base models are then combined into one model. Aggregate model implementation is the process of constructing several base models which are then combined into a single model for prediction. In essence, OVA classification is a method of aggregate modeling. This paper reports studies that were conducted to establish whether OVA classification can provide predictive performance gains when large volumes of data are available for modeling as is commonly the case in data mining. It is demonstrated in this paper that firstly, OVA modeling can be used to increase the amount of training data while at the same time using base model training sets whose size is much smaller than the total amount of available training data. Secondly, OVA models created from large datasets provide a higher level of predictive performance compared to single k-class models. Thirdly, the use of boosted OVA base models can provide higher predictive performance compared to un-boosted OVA base models. Fourthly, when the combination algorithm for base model predictions is able to resolve tied predictions, the resulting aggregate models provide a higher level of predictive performance.     

Interactive display of large solid models for walkthroughs

A new paradigm for designing complex engineering systems has emerged from computer graphics and CAD/CAM technology. Virtual design environments allow users to design and visualize all stages of the product. They not only free designers from the two dimensions of pencil and paper but also eliminate costly construction of physical mock-ups. We are developing the necessary technology for interactive walkthroughs of large mechanical and architectural models. This development includes model construction, display and interfacing with high-performance graphics systems and immersive technologies. Our ultimate goal is to create an environment where users will explore the complete model of a large design, such as a submarine, and verify that all constraints are satisfied in the same way they would a real one-by walking around in it. In applying our approach to a submarine storage and handling system model, we improved the overall frame rate by three to four times compared with rendering the polygonal B-rep. The online triangulation allows us to spend our rendering resources in the parts of the model significant for the current image. The overall system is currently being applied to large CAD models like submarines and fighting vehicles     

Application of machine learning techniques to analyse student interactions and improve the collaboration process

In e-learning environments that use the collaboration strategy, providing participants with a set of communication services may not be enough to ensure collaborative learning. It is thus necessary to analyse collaboration regularly and frequently. Using machine learning techniques is recommended when analysing environments where there are a large number of participants or where they control the collaboration process. This research studied two approaches that use machine learning techniques to analyse student collaboration in a long-term collaborative learning experience during the academic years 2006–2007, 2007–2008 and 2008–2009. The aims were to analyse collaboration during the collaboration process and that it should be domain independent. Accordingly, the intention was to be able to carry out the analysis regularly and frequently in different collaborative environments. One of the two approaches classifies students according to their collaboration using unsupervised machine learning techniques, clustering, while the other approach constructs metrics that provide information on collaboration using supervised learning techniques, decision trees. The research results suggest that collaboration can be analysed in this way, thus achieving the aims set out with two different machine learning techniques.     

Knowledge representation and inference techniques to improve the management of gas and oil facilities

This paper describes an experimental work carried out in the framework of an important European project to create and make use of a wide-ranging knowledge base in the gas/oil domain. In the context of this work, “knowledge base” means a collection of formal statement relating, with a negligible loss of information, the inner content (the ‘meaning’) of “complex events” included in two different “storyboards”. These events – originally presented under the form of unstructured natural language information – concern some general activities proper to the management of gas/oil facilities, like recognizing and monitoring gas leakage alarms in a gas processing plant or triggering the different steps needed to activate a gas turbine. To express this sort of information and to set up the knowledge base, the NKRL (Narrative Knowledge Representation Language) formalism has been used. NKRL is a conceptual meta-model and Computer Science environment expressly created to deal, in an ‘intelligent’ and complete way, with complex and content-rich ‘narrative’ data sources. The final knowledge base has been firstly tested in depth using the standard NKRL querying and information retrieval tools. High-level inference procedures have then been used, both “transformation rules” – unsuccessful queries are ‘transformed’ to produce results that are ‘semantically similar’ to those searched for initially – and “hypothesis rules” – information in the knowledge base is automatically aggregated to supply a sort of ‘causal’ explanation of some retrieved events.     

Evaluation of visual display techniques for assembly sequence planning

This study examined the effects of visual display formats for assembly planning tasks. A single assembly sequence was presented in: (a) a nonintegrated display format containing an arc and node diagram with an exploding graphic view of each step, and (b) an integrated display that incorporated pictures in the arc and node diagram and allowed enlargement of nodes. Both displays were tested with and without verbal and contextual information using five assembly rules. Overall, participants performed better and preferred the integrated display. Performance depended on the type of rule being examined. An integrated display format with verbal and contextual information is recommended for assembly sequence visualization. © 2001 John Wiley & Sons, Inc.     

Predicting movie success with machine learning techniques: ways to improve accuracy

Previous studies on predicting the box-office performance of a movie using machine learning techniques have shown practical levels of predictive accuracy. Their works are technically- and methodologically-oriented, focusing mainly on what algorithms are better at predicting the movie performance. However, the accuracy of prediction model can also be elevated by taking other perspectives such as introducing unexplored features that might be related to the prediction of the outcomes. In this paper, we examine multiple approaches to improve the performance of the prediction model. First, we develop and add a new feature derived from the theory of transmedia storytelling. Such theory-driven feature selection not only increases the forecast accuracy, but also enhances the interpretability of a prediction model. Second, we use an ensemble approach, which has rarely been adopted in the research on predicting box-office performance. As a result, the proposed model, Cinema Ensemble Model (CEM), outperforms the prediction models from the past studies that use machine learning algorithms. We suggest that CEM can be extensively used for industrial experts as a powerful tool for improving decision-making process.     

Configural display design techniques considered at multiple levels of evaluation

Two studies were conducted to examine issues in the design and evaluation of configural displays. Four design techniques (bar graphs/extenders, scale markers/ scale grids, color coding/color layering/color separation, and annotation with digital values) were applied, alone and in combination, to a baseline configural display, forming 10 displays. Two qualitatively different evaluations assessed performance for (A) low-level data probes (quantitative estimates of individual variables) and (B) system control and fault detection tasks. Three of the four design techniques improved performance significantly for low-level data probes (color coding was the exception). A display with digital values only (i.e., no analog configural display) produced the poorest performance for control/fault detection tasks. When both levels of evaluation are considered, a composite display (configural display with all four techniques applied) was clearly the most effective. Overall, the findings obtained in the two experiments provide very limited evidence for the generalization of results between evaluations. The two levels of evaluation, the display manipulations, and the patterns of results are considered in terms of a cognitive systems engineering evaluation framework. General implications for the evaluation of displays and interfaces are discussed. Actual or potential applications include design techniques to improve graphical displays and methodological insights to focus and improve evaluation efforts.     

Enabling the interactive display of large medical volume datasets by multiresolution bricking

In this paper, we present an approach to interactive out-of-core volume data exploration that has been developed to augment the existing capabilities of the LhpBuilder software, a core component of the European project LHDL (). The requirements relate to importing, accessing, visualizing and extracting a part of a very large volume dataset by interactive visual exploration. Such datasets contain billions of voxels and, therefore, several gigabytes are required just to store them, which quickly surpass the virtual address limit of current 32-bit PC platforms. We have implemented a hierarchical, bricked, partition-based, out-of-core strategy to balance the usage of main and external memories. A new indexing scheme is introduced, which permits the use of a multiresolution bricked volume layout with minimum overhead and also supports fast data compression. Using the hierarchy constructed in a pre-processing step, we generate a coarse approximation that provides a preview using direct volume visualization for large-scale datasets. A user can interactively explore the dataset by specifying a region of interest (ROI), which further generates a much more accurate data representation inside the ROI. If even more precise accuracy is needed inside the ROI, nested ROIs are used. The software has been constructed using the Multimod Application Framework, a VTK-based system; however, the approach can be adopted for the other systems in a straightforward way. Experimental results show that the user can interactively explore large volume datasets such as the Visible Human Male/Female (with file sizes of 3.15/12.03 GB, respectively) on a commodity graphics platform, with ease.     

Comparison of visual fatigue caused by head-mounted display for virtual reality and two-dimensional display using objective and subjective evaluation

This study aimed to evaluate objective and subjective visual fatigue experienced before and after performing a visual task while using a head-mounted display for virtual reality (VR-HMD) and two-dimensional (2D) display. Binocular fusion maintenance (BFM) was measured using a binocular open-view Shack–Hartmann wavefront aberrometer equipped with liquid crystal shutters. Twelve healthy subjects performed the BFM test and completed a questionnaire regarding subjective symptoms before and after performing a visual task that induces low visually induced motion sickness (VIMS). BFM (p = .87) and total subjective eye symptom scores (p = .38) were not significantly different between both groups, although these values were significantly lower after the visual task than before the task within both groups (p < .05). These findings suggest that visual fatigue after using a VR-HMD is not significantly different from that after using a 2D display in the presence of low-VIMS VR content.

Practitioner summary: Objective and subjective evaluation of visual fatigue were not significantly different with the use of a head-mounted display for virtual reality (VR-HMD) and two-dimensional display. These results should be valuable not only to engineers developing VR content but also to researchers involved in the evaluation of visual fatigue using VR-HMD.

Abbreviations: VR: virtual reality; VR-HMD: head-mounted display for virtual reality; BFM: binocular fusion maintenance; BWFA: binocular open-view Shack–Hartmann wavefront aberrometer     

On conformal and projective flatness of two-dimensional constant-Berwald Finsler spaces in epidemiology

Berwald connections with constant coefficients in two-dimensional Finsler spaces are important in the ecology of colonial organisms and also in the epidemiology of myxomatosis, the European wild rabbit disease. Because of the well-known results in the Riemannian case, only conformally flat or projectively flat Finsler spaces of constant-Berwald type are considered here. Complete classifications are given of the possible metric functions and their geodesics. New results on the myxomatosis model of Antonelli and Seymour modified to account for host/parasite ratio effects are discussed briefly in the final section.Partially supported by NSERC-A-7667     

Comparison of transform coding techniques for two-dimensional arbitrarily shaped images

Envisioned advanced multimedia video services include arbitrarily shaped (AS) image segments as well as regular rectangular images. Image segments of the TV weather report produced by the chromo-key technique [1] and image segments produced by video analysis and image segmentation [2–4] are typical examples of AS image segments. This paper explores efficient intraframe transform coding techniques for general two-dimensional (2D) AS image segments, treating the traditional rectangular images as a special case. In particular, we focus on the transform coding of the partially defined image blocks along the boundary of the AS image segments. We recognize two different approaches — thebrute force transform coding approach and theshape-adaptive transform coding approach. The former fills the uncovered area with the optimal redundant data such that the resulting transform spectrum is compact. A simple but efficient mirror image extension technique is proposed. Once augmented into full image blocks, these boundary blocks can be processed by traditional block-based transform techniques like the popular discrete cosine transform (DCT). In the second approach, we change either the transform basis or the coefficient calculation process adaptively based on the shape of the AS image segment. We propose an efficientshape-projected problem formulation to reduce the dimension of the problem. Existing coding algorithms, such as the orthogonal transform by Gilge [5] and the iterative coding by Kaup and Aach [6], can be interpreted intuitively. We also propose a new adaptive transform based on the same principle as that used in deriving the DCT from the optimal Karhunen-Loeve transform (KLT). We analyze the tradeoff relationship between compression performance, computational complexity, and codec complexity for different coding schemes. Simulation results show that complicated algorithms (e.g., iterative, adaptive) can improve the quality by 5–10 dB at some computational or hardware cost. Alternatively, the simple mirror image extension technique improves the quality by 3–4 dB without any overheads. The contributions of this paper lie in efficient problem formulations, new transform coding techniques, and numerical tradeoff analyses.     

LED大屏幕异步控制器多窗口显示的实现

介绍一种应用广泛的LED大屏幕异步控制器的设计方案。该系统采用高性能32位ARM微处理器为其控制核心,并且基于uc/OS-Ⅱ进行软件设计。可实现单屏幕多窗口任意位置的显示,使得屏幕显示变得丰富灵活。