HCI Bibliography Home | HCI Journals | About VLC | Journal Info | VLC Journal Volumes | Detailed Records | RefWorks | EndNote | Hide Abstracts
VLC Tables of Contents: 16171819202122232425

Journal of Visual Languages & Computing 20

Editors:S.-K. Chang; Stefano Levialdi
Standard No:ISSN: 1045-926X
Links:Table of Contents
  1. VLC 2009-02 Volume 20 Issue 1
  2. VLC 2009-04 Volume 20 Issue 2
  3. VLC 2009-06 Volume 20 Issue 3
  4. VLC 2009-08 Volume 20 Issue 4
  5. VLC 2009-10 Volume 20 Issue 5
  6. VLC 2009-12 Volume 20 Issue 6

VLC 2009-02 Volume 20 Issue 1

On user involvement in production of images used in visual authentication BIBAKFull-Text 1-15
  Karen Renaud
Recognition-based visual authentication schemes use a variety of different kinds of images. These mechanisms have now matured sufficiently that we should start considering tailoring and fine-tuning them -- looking at ways to make them more efficient. Since these mechanisms use images, the obvious starting point in this tailoring process is to consider the image type or genre being used by the mechanism.
   Images have a number of properties which are bound to influence the efficacy of the visual authentication mechanism. In this paper the notion of essential and tuning image properties is proposed. The former are those that an image must exhibit or possess in order to be used in visual authentication at all -- failure to meet these metrics should disqualify the image from use. Tuning properties, on the other hand, are properties that will improve the efficiency of the mechanism. The tuning property which is the focus of this paper is the user's involvement in the production of his/her secret images.
   A longitudinal study was carried out with a visual authentication system in order to determine the effectivity of images with three levels of user involvement, using randomly issued images from an archive, a set of hand-drawn images called doodles, and user-provided photos.
   The hand-drawn doodles performed better than both system-issued images and personal photos. Furthermore, whereas doodles demonstrate viability, personal photos have many insuperable problems which make them unsuitable for use in a security setting.
Keywords: Security; Visual authentication; Image type
End-user strategy programming BIBAKFull-Text 16-29
  Christoph Neumann; Ronald A. Metoyer; Margaret Burnett
Rule-based programming systems can be fragile because they force the user to account for all logical alternatives. If an unconsidered case does arise during execution, program behavior falls through the cracks into unspecified behavior. We investigate rule-based, end-user strategy programming by introducing our Interactive Football Playbook -- a domain specific, end-user programming environment to allow American football coaches to create animated football scenarios by associating strategy information with virtual football players. We address the problem of rule explosion through "rule bending" to support a minimalist, scaffolding-driven programming environment. Additionally, we introduce visual language representations for logical and sequential "and" to mitigate end-user confusion with the semantic meaning of these "and" constructs.
Keywords: End-user programming; Natural programming; Visual programming; Computer animation; American football
The expressiveness of spider diagrams augmented with constants BIBAKFull-Text 30-49
  Gem Stapleton; John Taylor; Simon Thompson; John Howse
Spider diagrams are a visual language for expressing logical statements or constraints. Several sound and complete spider diagram systems have been developed and it has been shown that they are equivalent in expressive power to monadic first order logic with equality. However, these sound and complete spider diagram systems do not contain syntactic elements analogous to constants in first order predicate logic. We extend the spider diagram language to include constant spiders which represent specific individuals. Formal semantics are given for the extended diagram language. We prove that this extended system is equivalent in expressive power to the language of spider diagrams without constants and, hence, equivalent to monadic first order logic with equality.
Keywords: Diagrammatic logic; Visual formalism; Formal methods
Cognitive support through visualization and focus specification for understanding large class libraries BIBAKFull-Text 50-59
  Jauhar Ali
Effective object-oriented (OO) programming requires understanding class libraries. This paper presents our approach to design and build a cognitive tool that supports a programmer to understand OO class libraries. The MUDRIK system provides (1) three-dimensional visualization mechanisms for representing class structures and relationships from a variety of views and (2) flexible focus specification mechanisms that allow users to adapt a space of components to be displayed according to the task at hand. Interactive views of MUDRIK enable programmers to examine components' detail while maintaining a global representation of the rest of the library. The paper describes why understanding class library is critical in OO programming, presents a cognitive framework of our approach and design rationale behind the system design, and provides a detailed description of the system followed by a discussion on our approach.
Keywords: Class library understanding; Software visualization; 3D visualization; Java programming; Cognitive tools; Reuse; Human-computer interaction

VLC 2009-04 Volume 20 Issue 2

Immersive authoring of Tangible Augmented Reality content: A user study BIBAKFull-Text 61-79
  Gun A. Lee; Gerard J. Kim
Immersive authoring refers to the style of programming or developing content from within the target-executable environment. Immersive authoring is important for fields such as augmented reality (AR) in which interaction usability and user perception of the target content must be checked first hand, in situ. In addition, the interaction efficiency and usability of the authoring tools itself is equally important for ease of authoring. In this paper, we propose design principles and describe an implementation of an immersive authoring system for AR. More importantly, we present a formal user study demonstrating its benefits and weaknesses. In particular, our results demonstrate that, compared to using the traditional 2D desktop development method, immersive authoring gained significant efficiency in specifying spatial arrangements and behavior tasks, a major component of AR content authoring. However, it was not so successful for abstract tasks such as logical programming. Based on this result, we suggest that a comprehensive AR authoring tool should include such immersive authoring functionality to help, particularly non-technical media artists, create effective contents based on the characteristics of the underlying media and interaction style.
Keywords: Immersive authoring; Augmented reality; Tangible interface; User study; Interaction design
Personal verification based on extraction and characterisation of retinal feature points BIBAKFull-Text 80-90
  Marcos Ortega; M. G. Penedo; J. Rouco; N. Barreira; M. J. Carreira
This paper describes a methodology of verification of individuals based on a retinal biometric pattern. The pattern consists in feature points of the retinal vessel tree, namely bifurcations and crossovers. These landmarks are detected and characterised adding semantic information to the biometric pattern. The typical authentication process of a person once extracted the biometric pattern includes matching it with the stored pattern for the authorised user obtaining a similarity value between them. A matching algorithm and a deep analysis of similarity metrics performance is presented. The semantic information added for the feature points allows to reduce the computation load in the matching process as only points classified equally can be matched. The system is capable of establishing a safe confidence band in the similarity measure space between scores for patterns of the same individual and between different individuals.
Keywords: Verification system; Similarity measure; Retinal images; Biometric pattern; Feature points matching
A multiexpert collaborative biometric system for people identification BIBAKFull-Text 91-100
  Maria De Marsico; Michele Nappi; Daniel Riccio; Genny Tortora
Present identification through single-biometric systems suffer from a number of limitations, due to the fact that no single bodily or behavioral feature is able to satisfy at the same time acceptability, speed and reliability constraints of authentication in real applications. Multibiometric systems can solve a number of problems of single-biometry approaches. A crucial issue to be investigated relates to how results from different systems should be evaluated and fused, in order to obtain an as reliable as possible global response. A further source of flaws for present systems, both single-biometric and multibiometric, can be found in the lack of dynamic update of parameters, which does not allow them to adapt to changes in the working settings. They are generally calibrated once and for all, so that they are tuned and optimized with respect to specific conditions. In this work, we investigate an architecture where single-biometry subsystems work in parallel, yet exchanging information at fixed points, according to the N-Cross Testing Protocol. In particular, the integrated subsystems work on the same biometric feature, the face in this case, yet exploiting different classifiers. Notice that such specific configuration is interesting to underline how the strengths of one classifier can compensate for flaws of other classifiers, so that the final result is more accurate and reliable. Moreover, parameters of each subsystem are also dynamically optimized according to the behavior of all the others. This is achieved by an additional component, the supervisor module, which analyzes the responses from all subsystems and modifies the degree of reliability required from each of them to accept the respective responses. In this way subsystems collaborate at a twofold level, both for returning a common answer and for tuning to changing operating conditions. The paper explores the combination of these two novel approaches, demonstrating that component collaboration increases system accuracy and allows identifying unstable subsystems.
Keywords: Biometric systems; Score fusion; Supervised reliability indexes
Group-specific face verification using soft biometrics BIBAKFull-Text 101-109
  Gian Luca Marcialis; Fabio Roli; Daniele Muntoni
Soft biometrics have been recently proposed for improving the verification performance of biometric recognition systems. Examples of soft biometrics are skin, eyes, hair colour, height, and ethnicity. Some of them are often cheaper than "hard", standard biometrics (e.g., face and fingerprints) to extract. They exhibit a low discriminant power for recognizing persons, but can add some evidences about the personal identity, and can be useful for a particular set of users. In particular, it is possible to argue that users with a certain high discriminant soft biometric can be better recognized. Identifying such users could be useful in exploiting soft biometrics at the best, as deriving an appropriate methodology for embedding soft-biometric information into the score computed by the main biometric.
   In this paper, we propose a group-specific algorithm to exploit soft-biometric information in a biometric verification system. Our proposal is exemplified using hair colour and ethnicity as soft biometrics and face as biometric. Hair colour and information about ethnicity can be easily extracted from face images, and used only for a small number of users with highly discriminant hair colour or ethnicity. We show by experiments that for those users, hair colour or ethnicity strongly contributes to reduce the false rejection rate without a significant impact on the false acceptance rate, whilst the performance does not change for other users.
Keywords: Biometrics; Soft biometrics; Face verification
Towards realism in drawing areas of interest on architecture diagrams BIBAKFull-Text 110-128
  Heorhiy Byelas; Alexandru Telea
Areas of interest (AOIs) are defined as groups of elements of system architecture diagrams that share some common property. Visualizing AOIs is a useful addition to plain diagrams, such as UML diagrams. Some methods have been proposed to automatically draw AOIs on UML diagrams. However, it is not clear whether actual users perceive the results of such methods to be better or worse as compared to human-drawn AOI, and what needs to be improved. We present here a process of studying and improving the perceived quality of computer-drawn AOI. For this, we conducted a qualitative evaluation that delivered insight in how users perceive the quality of computer-drawn AOIs as compared to hand-drawn diagrams. Following these results, we derived and implemented several improvements to an existing algorithm for computer-drawn AOIs. Next, we designed a distance metric to quantitatively compare different AOI drawings, and used this metric to show that our improved rendering algorithm creates drawings which are closer to (good) human drawings than the original rendering algorithm. We present here the results of the user evaluation, our improved algorithm for drawing AOIs, and the quantitative analysis performed to compare different drawings. The combined user evaluation, algorithmic improvements, and quantitative comparison method support our claim of having improved the perceived quality and understandability of AOI rendered on architecture diagrams.
Keywords: UML diagrams; Software visualization; Information visualization; Empirical evaluations; Visual shape comparison

VLC 2009-06 Volume 20 Issue 3

Introduction to the special issue on Advances in Multimodal Biometric Systems BIBFull-Text 129-130
  Michele Nappi; Genny Tortora
Computational methods for modeling facial aging: A survey BIBAKFull-Text 131-144
  Narayanan Ramanathan; Rama Chellappa; Soma Biswas
Facial aging, a new dimension that has recently been added to the problem of face recognition, poses interesting theoretical and practical challenges to the research community. The problem which originally generated interest in the psychophysics and human perception community has recently found enhanced interest in the computer vision community. How do humans perceive age? What constitutes an age-invariant signature that can be derived from faces? How compactly can the facial growth event be described? How does facial aging impact recognition performance? In this paper, we give a thorough analysis on the problem of facial aging and further provide a complete account of the many interesting studies that have been performed on this topic from different fields. We offer a comparative analysis of various approaches that have been proposed for problems such as age estimation, appearance prediction, face verification, etc. and offer insights into future research on this topic.
Keywords: Age progression; Age estimation; Craniofacial growth; Face recognition
Linguistics and face recognition BIBAKFull-Text 145-155
  Harry Wechsler
We describe in this paper a novel biometric methodology for face recognition suitable to address pose, illumination, and expression (PIE) image variability, temporal change, flexible matching, and last but not least occlusion and disguise that are usually referred to as denial and deception. The adverse conditions listed above affect the scope and performance of biometric analysis vis-à-vis both training and testing. The conceptual framework proposed here draws support from discriminative methods using likelihood ratios. At the conceptual level it links forensics and biometrics, while at the implementation level it links the Bayesian framework and statistical learning theory. As many of the concerns listed usually affect only parts of the face, a non-parametric recognition-by-part approach is advanced here for the purpose of reliable face recognition. Recognition-by-parts facilitates authentication because it does not seek for explicit invariance. Instead, it handles variability using component-based configurations that are flexible enough to compensate among others for limited pose changes, if any, and limited occlusion and disguise. The recognition-by-parts approach proposed here supports incremental and progressive processing. It is similar in nature to modern linguistics and practical intelligence with the emphasis on semantics and pragmatics. Layered categorization starts with face detection using implicit rather than explicit segmentation. It proceeds with face authentication that involves feature selection of local patch instances including dimensionality reduction, exemplar-based clustering of patches into parts, and data fusion for matching using boosting driven by parts that play the role of weak learners. The implementation, driven by transduction, employs proximity and typicality (ranking) realized using strangeness and random deficiency p-values, respectively. The feasibility and reliability of the proposed architecture has been validated using FERET and FRGC data. The paper concludes with suggestions for augmenting and enhancing the scope and utility of the recognition-by-parts architecture.
Keywords: Authentication; Biometrics; Boosting; Clustering; Cross-validation; Data fusion; Face recognition; Feature selection; FERET; Forensics; FRGC; ICA; k Nearest neighbor; Likelihood ratio; Linguistics; Margin; MDL; Multimodal integration; Neyman-Pearson; Occlusion; Recognition; p-Values; Parsing; Random deficiency; Ranking; Recognition-by-parts; Segmentation; SIFT; Strangeness; Surveillance; Transduction; Typicality
Normal maps vs. visible images: Comparing classifiers and combining modalities BIBAKFull-Text 156-168
  Andrea Francesco Abate; Maria De Marsico; Stefano Ricciardi; Daniel Riccio
This work investigates face recognition based on normal maps, and the performance improvement that can be obtained when exploiting it within a multimodal system, where a further independent module processes visible images. We first propose a technique to align two 3D models of a face by means of normal maps, which is very fast while providing an accuracy comparable to well-known and more general techniques such as Iterative Closest Point (ICP). Moreover, we propose a matching criterion based on a technique which exploits difference maps. It does not reduce the dimension of the feature space, but performs a weighted matching between two normal maps. In the second place, we explore the range of performances offered by different linear and nonlinear classifiers, when applied to the normal maps generated from the above aligned models. Such experiments highlight the added value of chromatic information contained in normal maps. We analyse a solid list of classifiers which were selected due to their historical reference value (e.g. Principal Component Analysis) or to their good performances in the bidimensional setting (Linear Discriminant Analysis, Partitioned Iterated Function Systems). Last but not least, we perform experiments to measure how different ways of combining normal maps and visible images can enhance the results obtained by the single recognition systems, given that specific characteristics of the images are taken into account. For these last experiments we only consider the classifier giving the best average results in the preceding ones, namely the PIFS-based one.
Keywords: Face recognition; Normal maps; Multimodal biometrics
Robustness of multimodal biometric fusion methods against spoof attacks BIBAKFull-Text 169-179
  Ricardo N. Rodrigues; Lee Luan Ling; Venu Govindaraju
In this paper, we address the security of multimodal biometric systems when one of the modes is successfully spoofed. We propose two novel fusion schemes that can increase the security of multimodal biometric systems. The first is an extension of the likelihood ratio based fusion scheme and the other uses fuzzy logic. Besides the matching score and sample quality score, our proposed fusion schemes also take into account the intrinsic security of each biometric system being fused. Experimental results have shown that the proposed methods are more robust against spoof attacks when compared with traditional fusion methods.
Keywords: Multimodal biometrics; Secure biometrics; Face recognition; Fingerprint
Person recognition using facial video information: A state of the art BIBAKFull-Text 180-187
  Federico Matta; Jean-Luc Dugelay
In this article we propose a detailed state of the art on person recognition using facial video information. We classify the existing approaches present in the scientific literature between those that neglect the temporal information, and those that exploit it even partially. Concerning the first category, we detail the extensions to video data of: eigenfaces, fisherfaces, active appearance models (AAMs), radial basis function neural networks (RBFNNs), elastic graph matching (EGM), hierarchical discriminative regression trees (HDRTs) and pairwise clustering methods. After that, we focus on the strategies exploiting the temporal information, in particular those analysing: the facial motion with optical flow, the evolution of facial appearance over time with hidden Markov models (HMMs) or with various probabilistic tracking and recognition approaches, and the head motion with Gaussian mixture models.
Keywords: Person recognition; Person identification; Person authentication; Person verification; Video; Facial information; State of the art; Survey
Audio-visual human recognition using semi-supervised spectral learning and hidden Markov models BIBAKFull-Text 188-195
  Wei Feng; Lei Xie; Jia Zeng; Zhi-Qiang Liu
This paper presents a multimodal system for reliable human identity recognition under variant conditions. Our system fuses the recognition of face and speech with a general probabilistic framework. For face recognition, we propose a new spectral learning algorithm, which considers not only the discriminative relations among the training data but also the generative models for each class. Due to the tedious cost of face labeling in practice, our spectral face learning utilizes a semi-supervised strategy. That is, only a small number of labeled faces are used in our training step, and the labels are optimally propagated to other unlabeled training faces. Besides requiring much less labeled data, our algorithm also enables a natural way to explicitly train an outlier model that approximately represents unauthorized faces. To boost the robustness of our system for human recognition under various environments, our face recognition is further complemented by a speaker identification agent. Specifically, this agent models the statistical variations of fixed-phrase speech using speaker-dependent word hidden Markov models. Experiments on benchmark databases validate the effectiveness of our face recognition and speaker identification agents, and demonstrate that the recognition accuracy can be apparently improved by integrating these two independent biometric sources together.
Keywords: Face recognition; Speaker identification; Semi-supervised spectral learning; Hidden Markov models (HMMs)
Dialogue patterns -- A visual language for dynamic dialogue BIBAKFull-Text 196-220
  J. Siegel; D. Szafron
A dynamic dialogue is a conversation in which each participant alternately selects remarks based on a changing world state and in which each remark can change the world state. Dynamic dialogues happen frequently as conversations between a player character (PC) and a non-player character (NPC) in a computer game. When it is the PC's turn to speak, the current game state is used to filter the static set of remarks available to the PC to a contextually appropriate subset that is made available to the player. Selecting a PC remark then leads to a candidate set of NPC remarks as appropriate responses to the PC. The world state is used to filter this set of remarks to a single remark, which is used by the NPC as the reply. To construct a dynamic dialogue, an author must not only create the remarks, but also write the code that determines which remarks are available to both participants at any point in the dialogue. We present "generative dialogue patterns" as a new visual language for designing dynamic dialogues and generating the program code that is necessary to select the appropriate remarks during the dialogue. We use a case study from the computer games domain to evaluate the effectiveness of generative dialogue patterns.
Keywords: Dynamic dialogue; Computer game; Design pattern; Generative; Scripting

VLC 2009-08 Volume 20 Issue 4

Special issue on selected papers from VL/HCC 2008: Guest Editors' introduction BIBFull-Text 221-222
  Paolo Bottoni; Mary Beth Rosson
Codetrail: Connecting source code and web resources BIBAKFull-Text 223-235
  Max Goldman; Robert C. Miller
When faced with the need for documentation, examples, bug fixes, error descriptions, code snippets, workarounds, templates, patterns, or advice, software developers frequently turn to their web browser. Web resources both organized and authoritative as well as informal and community-driven are heavily used by developers. The time and attention devoted to finding (or re-finding) and navigating these sites is significant. We present Codetrail, a system that demonstrates how the developer's use of web resources can be improved by connecting the Eclipse integrated development environment (IDE) and the Firefox web browser. Codetrail uses a communication channel and shared data model between these applications to implement a variety of integrative tools. By combining information previously available only to the IDE or the web browser alone (such as editing history, code contents, and recent browsing), Codetrail can automate previously manual tasks and enable new interactions that exploit the marriage of data and functionality from Firefox and Eclipse. Just as the IDE will change the contents of peripheral views to focus on the particular code or task with which the developer is engaged, so, too, the web browser can be focused on the developer's current context and task.
Keywords: Software development; Development environment; Web browser; Human-computer interaction
AgentCubes: Incremental 3D end-user development BIBAKFull-Text 236-251
  Andri Ioannidou; Alexander Repenning; David C. Webb
3D game development can be an enticing way to attract K-12 students to computer science, but designing and programming 3D games is far from trivial. Students need to achieve a certain level of 3D fluency in modeling, animation, and programming to be able to create compelling 3D content. The combination of innovative end-user development tools and standards-based curriculum that promotes IT fluency by shifting the pedagogical focus from programming to design, can address motivational aspects without sacrificing principled educational goals. The AgentCubes 3D game-authoring environment raises the ceiling of end-user development without raising the threshold. Our formal user study shows that with Incremental 3D, the gradual approach to transition from 2D to 3D authoring, middle school students can build sophisticated 3D games including 3D models, animations, and programming.
Keywords: Incremental 3D; Game design; Visual programming; End-user development; IT fluency; Computational thinking
Generic and reflective graph transformations for checking and enforcement of modeling guidelines BIBAKFull-Text 252-268
  Elodie Legros; Carsten Amelunxen; Felix Klar; Andy Schürr
In the automotive industry, the model driven development of software, today considered as the standard paradigm, is generally based on the use of the tool MATLAB Simulink/Stateflow. To increase the quality, the reliability, and the efficiency of the models and the generated code, checking and elimination of detected guideline violations defined in huge catalogs has become an essential task in the development process. It represents such a tremendous amount of boring work that it must necessarily be automated. In the past we have shown that graph transformation tools like Fujaba/MOFLON allow for the specification of single modeling guidelines on a very high level of abstraction and that guideline checking tools can be generated from these specifications easily. Unfortunately, graph transformation languages do not offer appropriate concepts for reuse of specification fragments -- a MUST, when we deal with hundreds of guidelines. As a consequence we present an extension of MOFLON that supports the definition of generic rewrite rules and combines them with the reflective programming mechanisms of Java and the model repository interface standard Java Metadata Interface (JMI).
Keywords: Graph transformation; Generic rules; Reflection
Automatic detection of dimension errors in spreadsheets BIBAKFull-Text 269-283
  Chris Chambers; Martin Erwig
We present a reasoning system for inferring dimension information in spreadsheets. This system can be used to check the consistency of spreadsheet formulas and thus is able to detect errors in spreadsheets.
   Our approach is based on three static analysis components. First, the spatial structure of the spreadsheet is analyzed to infer a labeling relationship among cells. Second, cells that are used as labels are lexically analyzed and mapped to potential dimensions. Finally, dimension information is propagated through spreadsheet formulas. An important aspect of the rule system defining dimension inference is that it works bi-directionally, that is, not only "downstream" from referenced arguments to the current cell, but also "upstream" in the reverse direction. This flexibility makes the system robust and turns out to be particularly useful in cases when the initial dimension information that can be inferred from headers is incomplete or ambiguous.
   We have implemented a prototype system as an add-in to Excel. In an evaluation of this implementation we were able to detect dimension errors in almost 50% of the investigated spreadsheets, which shows (i) that the system works reliably in practice and (ii) that dimension information can be well exploited to uncover errors in spreadsheets.
Keywords: Spreadsheet; Dimension; Unit of measurement; Static analysis; Inference rule; Error detection

VLC 2009-10 Volume 20 Issue 5

Introduction to the special issue on multimodal interaction through haptic feedback BIBFull-Text 285-286
  Maria De Marsico; Giuliana Vitiello
Enhancing personal communication with spatial haptics: Two scenario-based experiments on gestural interaction BIBAKFull-Text 287-304
  Jani Heikkinen; Jussi Rantala; Thomas Olsson; Roope Raisamo; Jani Lylykangas; Jukka Raisamo; Veikko Surakka; Teemu Ahmaniemi
Haptic gestures and sensations through the sense of touch are currently unavailable in remote communication. There are two main reasons for this: good quality haptic technology has not been widely available and knowledge on the use of this technology is limited. To address these challenges, we studied how users would like to, and managed to create spatial haptic information by gesturing. Two separate scenario-based experiments were carried out: an observation study without technological limitations, and a study on gesturing with a functional prototype with haptic actuators. The first study found three different use strategies for the device. The most common gestures were shaking, smoothing and tapping. Multimodality was requested to create the context for the communication and to aid the interpretation of haptic stimuli. The second study showed that users were able to utilize spatiality in haptic messages (e.g., forward-backward gesture for agreement). However, challenges remain in presenting more complex information via remote haptic communication. The results give guidance for communication activities that are usable in spatial haptic communication, and how to make it possible to enable this form of communication in reality.
Keywords: Haptics; Communication; Gestures; User study; Prototype; Scenarios
Vibrotactile feedback to aid blind users of mobile guides BIBAKFull-Text 305-317
  Giuseppe Ghiani; Barbara Leporini; Fabio Paternò
In this work, we report on a solution for providing support to the blind using mobile museum guides by exploiting the haptic channel as a complement to the audio/vocal one. The overall goal is to improve the autonomy and social integration of blind visitors. We followed an iterative approach in which the proposed system went through various user evaluations and further refinements. The final solution includes vibrotactile feedback enhancement for orientation and obstacle avoidance obtained through the use of unobtrusive actuators applied to two of the user's fingers combined with an electronic compass and obstacle detector sensors connected wirelessly to the mobile guide. Our study indicates that vibrotactile feedback is particularly useful to provide frequent unobtrusive indications of useful dynamic information, such as the level of proximity of an obstacle or the distance from the right orientation.
Keywords: Mobile guide; Accessibility; Blind users; Vibrotactile feedback; Multi-modal user interfaces
A haptic-based approach to virtual training for aerospace industry BIBAKFull-Text 318-325
  Andrea F. Abate; Mariano Guida; Paolo Leoncini; Michele Nappi; Stefano Ricciardi
In the last years, the industrial world has been increasingly adopting computer-aided solutions for design for maintainability and maintenance training tasks with the goal to reduce development costs and to shorten time, and to improve product and service quality. Computer-based training systems created to simulate machine assembly maintenance are normally operated by means of ordinary human-computer interfaces (keyboard, mouse, etc.), but this usually results in systems that are far from the real procedures, and therefore not effective in terms of training. In this study, we show that a better solution may come from the combination of virtual reality techniques and haptic interaction. To this regard, we present the results of a research aimed at testing and evaluating the effectiveness of the haptic feedback for first-person maintenance tasks targeted to the aerospace industry. The proposed system implements an interaction environment in which each of the main maintenance activities can be simulated by the trainee exploiting a hand-based commercial haptic device, operated by means of specific haptic-rendering techniques to provide realistic feedbacks during manipulation. A usability study is included to help assessing the potential of this approach.
Keywords: Hand based haptic interaction; Computer based training; Haptic rendering
Toward multimodal notation for mathematics: Why and how BIBAKFull-Text 326-340
  Cristian Bernareggi; Piero Mussio; Loredana Parasiliti Provenza
Notation is a tool of thought, recording and communicating concepts and activities related to a domain of knowledge. In the history of mathematical notation, written notation is usually considered. However, to be an effective thinking tool, notation must be properly perceived. Blind and partially sighted people run into difficulty in making, exploring and understanding mathematical concepts conceived for being represented in multi-dimensional space. In this paper, we capitalize on the multifaceted nature of digital symbols to define multimodal digital notation for graph structures that allows blind and partially sighted people to represent graph structures, reason about them and communicate their reasoning with sighted people as well as each other. As support tool for notation proposed we have designed a multimodal interactive system, in which haptic signals play a crucial role. An evolutionary prototype of the system has been developed and evaluated according to the star life cycle model.
Keywords: Multimodal notation; Visually impaired users; Haptic I/O; Interaction styles
Tactile feedback enhanced hand gesture interaction at large, high-resolution displays BIBAKFull-Text 341-351
  Stephanie Foehrenbach; Werner A. König; Jens Gerken; Harald Reiterer
Human beings perceive their surroundings based on sensory information from diverse channels. However, for human-computer interaction we mostly restrict the user on visual perception. In this paper, we contribute to the investigation of tactile feedback as an additional perception modality. Therefore, we will first discuss existing user studies and provide a classification scheme for tactile feedback techniques. We will then present and discuss a comparative evaluation study based on the ISO 9241-9 [Ergonomic requirements for office work with visual display terminals (VDTs) -- Part 9: requirements for non-keyboard input devices, 2000]. The 20 participants performed horizontal and vertical one-directional tapping tasks with hand gesture input with and without tactile feedback in front of a large, high-resolution display. In contrast to previous research, we cannot confirm a benefit of tactile feedback on user performance. Our results show no significant effect in terms of throughput (effective index of performance (IPe)) and even a significant higher error rate for horizontal target alignment when using tactile feedback. Based on these results, we suggest that tactile feedback can interfere with other senses in a negative way, resulting in the observed higher error rate for horizontal targets. Therefore, more systematic research is needed to clarify the influencing factors on the usefulness of tactile feedback. Besides these results, we found a significant difference in favor of the horizontal target alignment compared with the vertical one in terms of the effective index of performance (IPe), confirming the work by Dennerlein et al. [Force feedback improves performance for steering and combined steering-targeting tasks, in: CHI '00: Proceedings of the SIGCHI Conference on Human Factors in Computing Systems, ACM, New York, NY, USA, 2000, pp. 423-429].
Keywords: Hand gestures; Tactile feedback; Fitts' Law; Controlled experiment; Input device; Large high-resolution display

VLC 2009-12 Volume 20 Issue 6

Audio-video biometric recognition for non-collaborative access granting BIBAKFull-Text 353-367
  Christian Micheloni; Sergio Canazza; Gian Luca Foresti
In this paper, the problem of non-collaborative person identification for a secure access to facilities is addressed. The proposed solution adopts a face and a speaker recognition techniques. The integration of these two methods allows to improve the performance with respect to the two classifiers.
   In non-collaborative scenarios, the problem of face recognition first requires to detect the face pattern then to recognize it even when in non-frontal poses. In the current work, a histogram normalization, a boosting technique and a linear discrimination analysis have been exploited to solve typical problems like illumination variability, occlusions, pose variation, etc. In addition, a new temporal classification is proposed to improve the robustness of the frame-by-frame classification. This allows to project known classification techniques for still image recognition into a multi-frame context where the image capture allows dynamics in the environment.
   For the audio, a method for the automatic speaker identification in noisy environments is presented. In particular, we propose an optimization of a speech de-noising algorithm to optimize the performance of the extended Kalman filter (EKF). To provide a baseline system for the integration with our proposed speech de-noising algorithm, we use a conventional speaker recognition system, based on Gaussian mixture models and mel frequency cepstral coefficients (MFCCs) as features.
   To confirm the effectiveness of our methods, we performed video and speaker recognition tasks first separately then integrating the results. In particular, two different corpora have been used: (a) a public corpus (ELDSR for audio and FERRET for images) and (b) a dedicated audio/video corpus, in which the speakers read a list of sentences wearing a scarf or a full-face motorcycle helmet. Experimental results show that our methods are able to reduce significantly the classification error rate.
Keywords: Face recognition; Face detection; Audio de-noising; Speaker recognition
Deriving topological relations between regions from direction relations BIBAKFull-Text 368-384
  Luo Guo; Shihong Du
The integration of topological and direction relations plays an important role in many applications, like spatial databases and pictorial retrieval systems. The method for deriving composition of binary topological relations cannot always yield unique or interesting results. Therefore, to integrate efficiently topological and direction relations, some new mechanisms are required to derive topological relations from direction cases when the above situations occur. This paper presents the computation methods for deriving topological relations from direction relations. The methods fall into two categories: the derivation of topological relations from one direction relation and two direction relations. Our methods can provide topological information when topological relations are unavailable, or more precise results are expected. Thus they are helpful in the integration of the calculi for topological and direction relations.
Keywords: Qualitative spatial reasoning; Topological relations; Direction relations; Direction relation matrix; 9-intersection model
Drawing graphs with nonuniform nodes using potential fields BIBAKFull-Text 385-402
  Chun-Cheng Lin; Hsu-Chun Yen; Jen-Hui Chuang
Graphs with nonuniform nodes arise naturally in many real-world applications. Although graph drawing has been a very active research in the computer science community during the past decade, most of the graph drawing algorithms developed thus far have been designed for graphs whose nodes are represented as single points. As a result, it is of importance to develop drawing methods for graphs whose nodes are of different sizes and shapes, in order to meet the need of real-world applications. To this end, a potential field approach, coupled with an idea commonly found in force-directed methods, is proposed in this paper for drawing graphs with nonuniform nodes in 2-D and 3-D. In our framework, nonuniform nodes are uniformly charged, while edges are modelled by springs. Using certain techniques developed in the field of potential-based path planning, we are able to find analytically tractable procedures for computing the repulsive force and torque of a node in the potential field induced by the remaining nodes. The crucial feature of our approach is that the rotation of every nonuniform node and the multiple edges between two nonuniform nodes are taken into account. In comparison with the existing algorithms found in the literature, our experimental results suggest this new approach to be promising, as drawings of good quality for a variety of moderate-sized graphs in 2-D and 3-D can be produced reasonably efficiently. That is, our approach is suitable for moderate-sized interactive graphs or larger-sized static graphs. Furthermore, to illustrate the usefulness of our new drawing method for graphs with zero-sized nodes, we give an application to the visualization of hierarchical clustered graphs, for which our method offers a very efficient solution.
Keywords: Graph drawing; Potential field
Node overlap removal in clustered directed acyclic graphs BIBAKFull-Text 403-419
  Pushpa Kumar; Kang Zhang
Graph drawing and visualization represent structural information as diagrams of abstract graphs and networks. An important subset of graphs is directed acyclic graphs (DAGs). This paper presents a new E-Spring algorithm, extended from the popular spring embedder model, which eliminates node overlaps in clustered DAGs. In this framework, nodes are modeled as non-uniform charged particles with weights, and a final drawing is derived by adjusting the positions of the nodes according to a combination of spring forces and repulsive forces derived from electrostatic forces between the nodes. The drawing process needs to reach a stable state when the average distances of separation between nodes are near optimal. We introduce a stopping condition for such a stable state, which reduces equilibrium distances between nodes and therefore results in a significantly reduced area for DAG visualization. It imposes an upper bound on the repulsive forces between nodes based on graph geometry. The algorithm employs node interleaving to eliminate any residual node overlaps. These new techniques have been validated by visualizing eBay buyer-seller relationships and has resulted in overall area reductions in the range of 45-79%.
Keywords: Graph visualization; Spring algorithm; Directed acyclic graphs; Node overlap
Phenomena -- A visual environment for querying heterogenous spatial data BIBAKFull-Text 420-436
  Luca Paolino; Monica Sebillo; Genoveffa Tortora; Giuliana Vitiello; Robert Laurini
The need to perform complex analysis and decision making tasks has motivated growing interest in Geographic Information Systems (GIS) as a means to compare different scenarios and simulate the evolution of a phenomenon. However, data and function complexity may critically affect human interaction and system performances during planning and prevention activities. This is especially true when the scenarios of interest involve continuous fields, besides discrete objects.
   In the present paper we describe the visual environment Phenomena, where continuous and discrete data may be handled through a uniform approach. We illustrate how users' activity is supported by a visual framework where they can interact with, manipulate and query heterogeneous data, with a very small training effort. A preliminary experimental study suggests that when users perform complex tasks, a higher usability degree may be achieved compared to the adoption of a textual spatial SQL.
Keywords: Visual environments; Visual query languages; Geographic information systems; Continuous fields; Usability evaluation