| 1. |
- Liu, Yuanhua, 1971, et al.
(author)
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Considering the importance of user profiles in interface design
- 2009
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In: User Interfaces. ; , s. 23-
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Book chapter (other academic/artistic)abstract
- User profile is a popular term widely employed during product design processes by industrial companies. Such a profile is normally intended to represent real users of a product. The ultimate purpose of a user profile is actually to help designers to recognize or learn about the real user by presenting them with a description of a real user’s attributes, for instance; the user’s gender, age, educational level, attitude, technical needs and skill level. The aim of this chapter is to provide information on the current knowledge and research about user profile issues, as well as to emphasize the importance of considering these issues in interface design. In this chapter, we mainly focus on how users’ difference in expertise affects their performance or activity in various interaction contexts. Considering the complex interaction situations in practice, novice and expert users’ interactions with medical user interfaces of different technical complexity will be analyzed as examples: one focuses on novice and expert users’ difference when interacting with simple medical interfaces, and the other focuses on differences when interacting with complex medical interfaces. Four issues will be analyzed and discussed: (1) how novice and expert users differ in terms of performance during the interaction; (2) how novice and expert users differ in the perspective of cognitive mental models during the interaction; (3) how novice and expert users should be defined in practice; and (4) what are the main differences between novice and expert users’ implications for interface design. Besides describing the effect of users’ expertise difference during the interface design process, we will also pinpoint some potential problems for the research on interface design, as well as some future challenges that academic researchers and industrial engineers should face in practice.
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| 2. |
- Boström, Henrik
(author)
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Maximizing the Area under the ROC Curve with Decision Lists and Rule Sets
- 2007
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In: Proceedings of the 7th SIAM International Conference on Data Mining. - : Society for Industrial and Applied Mathematics. - 9780898716306 ; , s. 27-34
-
Conference paper (peer-reviewed)abstract
- Decision lists (or ordered rule sets) have two attractive properties compared to unordered rule sets: they require a simpler classi¯cation procedure and they allow for a more compact representation. However, it is an open question what effect these properties have on the area under the ROC curve (AUC). Two ways of forming decision lists are considered in this study: by generating a sequence of rules, with a default rule for one of the classes, and by imposing an order upon rules that have been generated for all classes. An empirical investigation shows that the latter method gives a significantly higher AUC than the former, demonstrating that the compactness obtained by using one of the classes as a default is indeed associated with a cost. Furthermore, by using all applicable rules rather than the first in an ordered set, an even further significant improvement in AUC is obtained, demonstrating that the simple classification procedure is also associated with a cost. The observed gains in AUC for unordered rule sets compared to decision lists can be explained by that learning rules for all classes as well as combining multiple rules allow for examples to be ranked according to a more fine-grained scale compared to when applying rules in a fixed order and providing a default rule for one of the classes.
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| 3. |
- Hedenberg, Klas, 1968-, et al.
(author)
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Obstacle Detection For Thin Horizontal Structures
- 2008
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In: World Congress on Engineering and Computer Science. - Hong Kong : International Association of Engineers. - 9789889867102 ; , s. 689-693
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Conference paper (peer-reviewed)abstract
- Many vision-based approaches for obstacle detection often state that vertical thin structure is of importance, e.g. poles and trees. However, there are also problem in detecting thin horizontal structures. In an industrial case there are horizontal objects, e.g. cables and fork lifts, and slanting objects, e.g. ladders, that also has to be detected. This paper focuses on the problem to detect thin horizontal structures. The system uses three cameras, situated as a horizontal pair and a vertical pair, which makes it possible to also detect thin horizontal structures. A comparison between a sparse disparity map based on edges and a dense disparity map with a column and row filter is made. Both methods use the Sum of Absolute Difference to compute the disparity maps. Special interest has been in scenes with thin horizontal objects. Tests show that the sparse dense method based on the Canny edge detector works better for the environments we have tested.
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| 4. |
- Magnusson, Andreas
(author)
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Evolutionary optimisation of a morphological image processor for embedded systems
- 2008
-
Doctoral thesis (other academic/artistic)abstract
- The work presented in this thesis concerns the design, development and implementation of two digital components to be used, primarily, in autonomously operating embedded systems, such as mobile robots. The first component is an image coprocessor, for high-speed morphological image processing, and the second is a hardware-based genetic algorithm coprocessor, which provides evolutionary computation functionality for embedded applications. The morphological image coprocessor, the Clutter-II, has been optimised for efficiency of implementation, processing speed and system integration. The architecture employs a compact hardware structure for its implementation of the morphological neighbourhood transformations. The compact structure realises a significantly reduced hardware resource cost. The resources saved by the compact structure can be used to increase parallelism in image processing operations, thereby improving processing speed in a similarly significant manner. The design of the Clutter-II as a coprocessor enables easy-to-use and efficient access to its image processing capabilities from the host system processor and application software. High-speed input-output interfaces, with separated instruction and data buses, provide effective communication with system components external to the Clutter-II. A substantial part of the work presented in this thesis concerns the practical implementation of morphological filters for the Clutter-II, using the compact transformation structure. To derive efficient filter implementations, a genetic algorithm has been developed. The algorithm optimises the filter implementation by minimising the number of operations required for a particular filter. The experience gained from the work on the genetic algorithm inspired the development of the second component, the HERPUC. HERPUC is a hardware-based genetic algorithm processor, which employs a novel hardware implementation of the selection mechanism of the algorithm. This, in combination with a flexible form of recombination operator, has made the HERPUC an efficient hardware implementation of a genetic algorithm. Results indicate that the HERPUC is able to solve the set of test problems, to which it has been applied, using fewer fitness evaluations and a smaller population size, than previous hardware-based genetic algorithm implementations.
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| 5. |
- Castellano, Ginevra, et al.
(author)
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Expressive Control of Music and Visual Media by Full-Body Movement
- 2007
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In: Proceedings of the 7th International Conference on New Interfaces for Musical Expression, NIME '07. - New York, NY, USA : ACM Press. ; , s. 390-391
-
Conference paper (peer-reviewed)abstract
- In this paper we describe a system which allows users to use their full-body for controlling in real-time the generation of an expressive audio-visual feedback. The system extracts expressive motion features from the user’s full-body movements and gestures. The values of these motion features are mapped both onto acoustic parameters for the real-time expressive rendering ofa piece of music, and onto real-time generated visual feedback projected on a screen in front of the user.
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| 6. |
- Castellano, Ginevra, et al.
(author)
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User-Centered Control of Audio and Visual Expressive Feedback by Full-Body Movements
- 2007
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In: Affective Computing and Intelligent Interaction. - Berlin / Heidelberg : Springer Berlin/Heidelberg. - 9783540748885 ; , s. 501-510
-
Book chapter (peer-reviewed)abstract
- In this paper we describe a system allowing users to express themselves through their full-body movement and gesture and to control in real-time the generation of an audio-visual feedback. The systems analyses in real-time the user’s full-body movement and gesture, extracts expressive motion features and maps the values of the expressive motion features onto real-time control of acoustic parameters for rendering a music performance. At the same time, a visual feedback generated in real-time is projected on a screen in front of the users with their coloured silhouette, depending on the emotion their movement communicates. Human movement analysis and visual feedback generation were done with the EyesWeb software platform and the music performance rendering with pDM. Evaluation tests were done with human participants to test the usability of the interface and the effectiveness of the design.
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| 7. |
- Mancini, Maurizio, et al.
(author)
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A virtual head driven by music expressivity
- 2007
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In: IEEE Transactions on Audio, Speech, and Language Processing. - : Institute of Electrical and Electronics Engineers (IEEE). - 1558-7916 .- 1558-7924. ; 15:6, s. 1833-1841
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Journal article (peer-reviewed)abstract
- In this paper, we present a system that visualizes the expressive quality of a music performance using a virtual head. We provide a mapping through several parameter spaces: on the input side, we have elaborated a mapping between values of acoustic cues and emotion as well as expressivity parameters; on the output side, we propose a mapping between these parameters and the behaviors of the virtual head. This mapping ensures a coherency between the acoustic source and the animation of the virtual head. After presenting some background information on behavior expressivity of humans, we introduce our model of expressivity. We explain how we have elaborated the mapping between the acoustic and the behavior cues. Then, we describe the implementation of a working system that controls the behavior of a human-like head that varies depending on the emotional and acoustic characteristics of the musical execution. Finally, we present the tests we conducted to validate our mapping between the emotive content of the music performance and the expressivity parameters.
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| 8. |
- Mancini, M., et al.
(author)
-
From acoustic cues to an expressive agent
- 2006
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In: Lecture Notes in Computer Science (including subseries Lecture Notes in Artificial Intelligence and Lecture Notes in Bioinformatics). - Berlin, Heidelberg : Springer Berlin Heidelberg. - 3540326243 ; , s. 280-291
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Conference paper (peer-reviewed)abstract
- This work proposes a new way for providing feedback to expressivity in music performance. Starting from studies on the expressivity of music performance we developed a system in which a visual feedback is given to the user using a graphical representation of a human face. The first part of the system, previously developed by researchers at KTH Stockholm and at the University of Uppsala, allows the real-time extraction and analysis of acoustic cues from the music performance. Cues extracted are: sound level, tempo, articulation, attack time, and spectrum energy. From these cues the system provides an high level interpretation of the emotional intention of the performer which will be classified into one basic emotion, such as happiness, sadness, or anger. We have implemented an interface between that system and the embodied conversational agent Greta, developed at the University of Rome "La Sapienza" and "University of Paris 8". We model expressivity of the facial animation of the agent with a set of six dimensions that characterize the manner of behavior execution. In this paper we will first describe a mapping between the acoustic cues and the expressivity dimensions of the face. Then we will show how to determine the facial expression corresponding to the emotional intention resulting from the acoustic analysis, using music sound level and tempo characteristics to control the intensity and the temporal variation of muscular activation.
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| 9. |
- Pousman, Zachary, et al.
(author)
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Living with Tableau Machine : A Longitudinal Investigation of a Curious Domestic Intelligence
- 2008
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In: Proceedings of the 10th International Conference on Ubiquitous Computing. - New York, NY, USA : ACM Press. ; , s. 370-379
-
Conference paper (peer-reviewed)abstract
- We present a longitudinal investigation of Tableau Machine, an intelligent entity that interprets and reflects the lives of occupants in the home. We created Tableau Machine (TM) to explore the parts of home life that are unrelated to accomplishing tasks. Task support for "smart homes" has inspired many researchers in the community. We consider design for experience, an orthogonal dimension to task-centric home life. TM produces abstract visualizations on a large LCD every few minutes, driven by a set of four overhead cameras that capture a sense of the social life of a domestic space. The openness and ambiguity of TM allow for a cycle of co-interpretation with householders. We report on three longitudinal deployments of TM for a period of six weeks. Participant families engaged with TM at the outset to understand how their behaviors were influencing the machine, and, while TM remained puzzling, householders interacted richly with TM and its images. We extract some key design implications for an experience-focused smart home.
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| 10. |
- Romero, Mario, et al.
(author)
-
A preliminary investigation of Alien Presence
- 2005
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In: Proceedings of Human-Computer Interaction International (HCII 2005), Las Vegas, NV, USA, July 2005. - : HCII.
-
Conference paper (peer-reviewed)abstract
- Work in ubiquitous computing and ambient intelligence tends to focus on information access and task supportsystems informed by the office environment, which tend to view the whole world as an office, or on surveillancesystems that feature asymmetric information access, providing interpretations of activity to a central authority. Thealien presence provides an alternative model of ambient intelligence; an alien presence actively interprets abstractqualities of human activity (e.g. mood, social energy) and reports these interpretations, not to a central authority, butback to the user’s themselves in the form of ambient, possibly physical displays. The goal of an alien presence is nottask accomplishment and efficient access to information, but rather to open unusual viewpoints onto everydayhuman activity, create pleasure, and provide opportunities for contemplation and wonder. The design of an alienpresence is an interdisciplinary endeavor drawing on artificial intelligence techniques, art practices of creation andcritique, and HCI methods of design and evaluation. In this paper we present preliminary work on the TableauxMachine, an alien presence designed for the home environment, as well as discuss a number of general design issuesof alien presence including co-interpretation, authorship, richness of expression vs. system complexity, tensionsbetween viewing computation as a medium vs. as a model, issues of privacy, and evaluation.
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| 11. |
- Romero, Mario, 1973-, et al.
(author)
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Alien Presence in the Home : The Design of Tableau Machine
- 2008
-
In: Personal and Ubiquitous Computing. - : Springer. - 1617-4909 .- 1617-4917. ; 12:5, s. 373-382
-
Journal article (peer-reviewed)abstract
- We introduce a design strategy, alien presence, which combines work in human---computer interaction, artificial intelligence, and media art to create enchanting experiences involving reflection over and contemplation of daily activities. An alien presence actively interprets and characterizes daily activity and reflects it back via generative, ambient displays that avoid simple one-to-one mappings between sensed data and output. We describe the alien presence design strategy for achieving enchantment, and report on Tableau Machine, a concrete example of an alien presence design for domestic spaces. We report on an encouraging formative evaluation indicating that Tableau Machine does indeed support reflection and actively engages users in the co-construction of meaning around the display.
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| 12. |
- Bouguerra, Abdelbaki, 1974-, et al.
(author)
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An autonomous robotic system for load transportation
- 2009
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In: 2009 IEEE Conference on Emerging Technologies & Factory Automation (EFTA 2009). - New York : IEEE conference proceedings. - 9781424427277 - 9781424427284 ; , s. 1563-1566
-
Conference paper (peer-reviewed)abstract
- This paper presents an overview of an autonomous robotic material handling system. The goal of the system is to extend the functionalities of traditional AGVs to operate in highly dynamic environments. Traditionally, the reliable functioning of AGVs relies on the availability of adequate infrastructure to support navigation. In the target environments of our system, such infrastructure is difficult to setup in an efficient way. Additionally, the location of objects to handle are unknown, which requires that the system be able to detect and track object positions at runtime. Another requirement of the system is to be able to generate trajectories dynamically, which is uncommon in industrial AGV systems.
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| 13. |
- Li, Liyuan, et al.
(author)
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An Efficient Sequential Approach to Tracking Multiple Objects through Crowds for Real-Time Intelligent CCTV Systems
- 2008
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In: IEEE Transactions on Systems, Man and Cybernetics Part B: Cybernetics. - 1083-4419. ; 38:5, s. 1254-1269
-
Journal article (peer-reviewed)abstract
- Efficiency and robustness are the two most important issues for multi-object tracking algorithms in real-time intelligent video surveillance systems. We propose a novel2 1/2 D approach to real time multi-object tracking in crowds, which is formulated as a MAP estimation problem and is approximated through an “assignment” step and a “location” step. Observing that the occluding object is usually less affected by the occluded objects, sequential solutions for the assignment and the location are derived. A novel dominant color histogram (DCH) is proposed as an efficient object model. The DCH can be regarded as a generalized color histogram, where dominant colors are selected based on a given distance measure. Comparing with conventional color histograms, DCH only requires a few color components (31 in average). Further, our theoretical analysis and evaluation on real data have shown that DCHs are robust to illumination changes. Using DCH, efficient implementations of sequential solutions for the assignment and the location steps are proposed. The "Assignment" step includes the estimation of depth order for the objects in a dispersing group, one-by-one assignment, and feature exclusion from the group representation. The "Location" step includes the depth order estimation for the objects in a new group, two-phase mean-shift location, and the exclusion of tracked objects from the new position in the group. Multi-object tracking results and evaluation from public datasets are presented. Experiments on image sequences captured from crowded public environments have shown good tracking results, where about 90% of objects have been successfully tracked with the correct identification numbers by the proposed method. Our results and evaluation have indicated that the method is efficient and robust for tracking multiple objects (large than or equal to 3) in complex occlusions for real world surveillance scenarios.
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| 14. |
- Wang, Tiesheng, 1975, et al.
(author)
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Face Tracking Using Rao-Blackwellized Particle Filter and Pose-Dependent Probabilistic PCA
- 2008
-
In: Proceedings - International Conference on Image Processing, ICIP. - 1522-4880. - 9781424417643 ; , s. 853-856
-
Conference paper (peer-reviewed)abstract
- This paper deals with face blob tracking, where face undergoes various pose changes. We propose a novel trackingmethod to deal with face pose changes during tracking. In the method, tracking is formulated as an approximate solution to the MAP estimate of state vector, consisting of a linear and a nonlinear part. Multi-pose face appearance is modeled by locally linear models, and estimated by the probabilistic PCA for individual pose combined with a Markov model for pose changes. Shape and locations of face blobs and pose index are assumed to be nonlinear and estimated by Rao-Blackwellized particle filters (RBPF), which also enables separate estimation of linear state vector through marginalizing the joint probability. The proposed method has been tested for videos containing frequent face pose changes and large illumination variations, under 5 pose models (left, frontal, right, up, down), and the tracking results are shown to be robust to varying speed pose changes and with relatively tight boxes.
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| 15. |
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| 16. |
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| 17. |
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| 18. |
- Faraj, Maycel, 1979-, et al.
(author)
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Synergy of lip motion and acoustic features in biometric speech and speaker recognition
- 2007
-
In: IEEE Transactions on Computers. - New York : IEEE Press. - 0018-9340 .- 1557-9956. ; 56:9, s. 1169-1175
-
Journal article (peer-reviewed)abstract
- This paper presents the scheme and evaluation of a robust audio-visual digit-and-speaker-recognition system using lip motion and speech biometrics. Moreover, a liveness verification barrier based on a person's lip movement is added to the system to guard against advanced spoofing attempts such as replayed videos. The acoustic and visual features are integrated at the feature level and evaluated first by a support vector machine for digit and speaker identification and, then, by a Gaussian mixture model for speaker verification. Based on ap300 different personal identities, this paper represents, to our knowledge, the first extensive study investigating the added value of lip motion features for speaker and speech-recognition applications. Digit recognition and person-identification and verification experiments are conducted on the publicly available XM2VTS database showing favorable results (speaker verification is 98 percent, speaker identification is 100 percent, and digit identification is 83 percent to 100 percent).
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| 19. |
- Jacobsson, Mattias
(author)
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Play, Belief and Stories about Robots : A Case Study of a Pleo Blogging Community
- 2009
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In: Proceedings of RO-MAN 2009. - NEW YORK : IEEE. ; , s. 830-835
-
Conference paper (other academic/artistic)abstract
- We present an analysis based on user-provided content collected from online blogs and forums about the robotic artifact Pleo. Our primary goal is to explore stories about how human-robot interaction would manifest themselves in actual real-world contexts. To be able to assess these types of communicative media we are using a method based on virtual ethnography that specifically addresses underlying issues in how the data is produced and should be interpreted. Results indicate that generally people are staging, performing and have a playful approach to the interaction. This is further emphasized by the way people communicate their stories through the blogging practice. Finally we argue that these resources are indeed essential for understanding and designing long-term human-robot relationships.
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| 20. |
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| 21. |
- Vidholm, Erik, et al.
(author)
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Hardware accelerated visualization of parametrically mapped dynamic breast MRI data
- 2007
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In: Proceedings of MICCAI workshop: Interaction in Medical Image Analysis and Visualization. - 978 0 643 09521 2 - 9780643095212 ; , s. 33-40, s. 33-40
-
Conference paper (peer-reviewed)abstract
- We present a new approach to visualising parametric vol-umes obtained in voxel-wise model fitting of dynamic contrast-enhanced(DCE) MRI data of the breast. The visualisation makes use of hardware-accelerated rendering to obtain an interactive, 3D colour-correct maxi-mum intensity projection (MIP). The method has been realised in soft-ware that permits the user to not only interactively visualise the paramet-ric volume but also to delineate 3D regions of interest using a 2D slice-wise interface. Experimental results, based on 14 DCE-MRI data setsfrom routine clinical practice, show that using the visualisation/tracingtool a medically qualified operator can achieve the same sensitivity forthe detection of malignancy as a radiologist using conventional manualinterpretation, but with better specificity. The results demonstrate thatthe visualisation methodology/software has potential as a tool for assist-ing the radiologist with the task of interpreting 4D DCE-MRI data inthe routine clinical setting.
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| 22. |
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| 23. |
- Backhouse, Andrew, 1978, et al.
(author)
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ML Nonlinear Smoothing for Image Segmentation and Its Relationship to The Mean Shift
- 2007
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In: IEEE International conf. on Image Processing (ICIP '07).
-
Conference paper (peer-reviewed)abstract
- This paper addresses the issues of nonlinear edge-preserving image smoothing and segmentation. A ML-based approach is proposed which uses an iterative algorithm to solve the problem. First, assumptions about segments are made by describing the joint probability distribution of pixel positions and colours within segments. Based on these assumptions, an optimal smoothing algorithm is derived under the ML condition. By studying the derived algorithm, we show that the solution is related to a two-stage mean shift which is separated in space and range. This novel ML-based approach takes a new kernel function. Experiments have been conducted on a range of images to smooth and segment them. Visual results and evaluations with 2 objective criteria have shown that the proposed method has led to improved results which suffer from less over-segmentation than the standard mean-shift.
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| 24. |
- Backhouse, Andrew, 1978, et al.
(author)
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Robust Object Tracking using Particle Filters and Multi-Region Mean Shift
- 2009
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In: Lecture Notes in Computer Science (including subseries Lecture Notes in Artificial Intelligence and Lecture Notes in Bioinformatics). - Berlin, Heidelberg : Springer Berlin Heidelberg. - 1611-3349 .- 0302-9743. - 9783642104664 ; 5879, s. 11-403
-
Conference paper (peer-reviewed)abstract
- In this paper, we introduce a novel algorithm which buildsupon the combined anisotropic mean-shift and particle filter framework. The anisotropic mean-shift with 5 degrees of freedom, is extended to work on a partition of the object into concentric rings. This adds spatial information to the description of the object which makes the algorithm more resilient to occlusion and less susceptible to confusion with objects having similar color densities. Experiments conducted on videos containing deformable objects with long-term partial occlusion (or, short-term full occlusion) and intersection have shown robust tracking performance, especially in tracking objects with long term partial occlusion, short term full occlusion, close color background clutter, severe object deformation and fast changing motion. Comparisons with two existing methods have shown marked improvement in terms of robustness to occlusions, tightness and accuracy of tracked box, and tracking drifts.
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| 25. |
- Berrada, Dounia, et al.
(author)
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Automatic Administration of the Get Up and Go Test
- 2007
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In: HealthNet'07. - New York, NY, USA : ACM Digital Library. ; , s. 73-75
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Conference paper (peer-reviewed)abstract
- In-home monitoring using sensors has the potential to improve the life of elderly and chronically ill persons, assist their family and friends in supervising their status, and provide early warning signs to the person's clinicians. The Get Up and Go test is a clinical test used to assess the balance and gait of a patient. We propose a way to automatically apply an abbreviated version of this test to patients in their residence using video data without body-worn sensors or markers.
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| 26. |
- Bhatt, Mehul, Professor, 1980-, et al.
(author)
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A Qualitative Model of Dynamic Scene Analysis and Interpretation in Ambient Intelligence Systems
- 2009
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In: International Journal of Robotics and Automation. - : ACTA Press. - 0826-8185 .- 1925-7090. ; 24:3, s. 235-244
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Journal article (peer-reviewed)abstract
- Ambient intelligence environments necessitate representing and reasoning about dynamic spatial scenes and configurations. The ability to perform predictive and explanatory analyses of spatial scenes is crucial towards serving a useful intelligent function within such environments. We present a formal qualitative model that combines existing qualitative theories about space with it formal logic-based calculus suited to modelling dynamic environments, or reasoning about action and change in general. With this approach, it is possible to represent and reason about arbitrary dynamic spatial environments within a unified framework. We clarify and elaborate on our ideas with examples grounded in a smart environment.
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| 27. |
- Bhatt, Mehul, Professor, 1980-, et al.
(author)
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Modelling Dynamic Spatial Systems in the Situation Calculus
- 2008
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In: Spatial Cognition and Computation. - : Taylor & Francis Group. - 1387-5868 .- 1573-9252 .- 1542-7633. ; 8:1-2, s. 86-130
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Journal article (peer-reviewed)abstract
- We propose and systematically formalise a dynamical spatial systems approach for the modelling of changing spatial environments. The formalisation adheres to the semantics of the situation calculus and includes a systematic account of key aspects that are necessary to realize a domain-independent qualitative spatial theory that may be utilised across diverse application domains. The spatial theory is primarily derivable from the all-pervasive generic notion of "qualitative spatial calculi" that are representative of differing aspects of space. In addition, the theory also includes aspects, both ontological and phenomenal in nature, that are considered inherent in dynamic spatial systems. Foundational to the formalisation is a causal theory that adheres to the representational and computational semantics of the situation calculus. This foundational theory provides the necessary (general) mechanism required to represent and reason about changing spatial environments and also includes an account of the key fundamental epistemological issues concerning the frame and the ramification problems that arise whilst modelling change within such domains. The main advantage of the proposed approach is that based on the structure and semantics of the proposed framework, fundamental reasoning tasks such as projection and explanation directly follow. Within the specialised spatial reasoning domain, these translate to spatial planning/re-configuration, causal explanation and spatial simulation. Our approach is based on the hypothesis that alternate formalisations of existing qualitative spatial calculi using high-level tools such as the situation calculus are essential for their utilisation in diverse application domains such as intelligent systems, cognitive robotics and event-based GIS.
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| 28. |
- Brun, Anders, 1976-, et al.
(author)
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Similar Tensor Arrays : A Framework for Storage of Tensor Array Data
- 2009. - 1
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In: Tensors in Image Processing and Computer Vision. - London : Springer. - 9781848822986 - 9781848822993 ; , s. 407-428
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Book chapter (other academic/artistic)abstract
- Abstract This chapter describes a framework for storage of tensor array data, useful to describe regularly sampled tensor fields. The main component of the framework, called Similar Tensor Array Core (STAC), is the result of a collaboration between research groups within the SIMILAR network of excellence. It aims to capture the essence of regularly sampled tensor fields using a minimal set of attributes and can therefore be used as a “greatest common divisor” and interface between tensor array processing algorithms. This is potentially useful in applied fields like medical image analysis, in particular in Diffusion Tensor MRI, where misinterpretation of tensor array data is a common source of errors. By promoting a strictly geometric perspective on tensor arrays, with a close resemblance to the terminology used in differential geometry, (STAC) removes ambiguities and guides the user to define all necessary information. In contrast to existing tensor array file formats, it is minimalistic and based on an intrinsic and geometric interpretation of the array itself, without references to other coordinate systems.
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| 29. |
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| 30. |
- Duca, Florin, et al.
(author)
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Real-Time 3D Hand Interaction: Single Webcam Low-Cost Approach
- 2007
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In: IEEE VR 2007 Workshop on Trends and issues in Tracking for Virtual Environments. - 0945-0807. ; , s. 1-5
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Conference paper (peer-reviewed)abstract
- The purpose of this project is to create a library that will allow its users to control 3D applications by using one or both of their hands. The final product could easily be incorporated into 3D applications, each customized to utilize a set of poses. Even though off-the-shelf motion capture gloves have reached lower prices in recent years, they are still expensive for home users. The algorithm suggested is based only on a single webcam combined with coded palm and fingers. Users should be able to code one or more of the fingers. One webcam is still somewhat constraining as two should ideally be used for 3D mapping of the hand, but by additionally using palm and finger coding we can greatly improve precision and, most importantly, reduce the processing power required for feasible real-time 3D interaction.
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| 31. |
- Ericson, Stefan, et al.
(author)
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Algorithms for Visual Odometry in Outdoor Field Environment
- 2007
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In: Proceedings of the 13th IASTED International Conference on Robotics and Applications. - Anaheim, Calif. : ACTA Press. - 9780889866850 - 9780889866867 ; , s. 287-292
-
Conference paper (peer-reviewed)abstract
- In this paper different algorithms for visual odometry are evaluated for navigating an agricultural weeding robot in outdoor field environment. Today there is an encoder wheel that keeps track of the weeding tools position relative the camera, but the system suffers from wheel slippage and errors caused by the uneven terrain. To overcome these difficulties the aim is to replace the encoders with visual odometry using the plant recognition camera. Four different optical flow algorithms are tested on four different surfaces, indoor carpet, outdoor asphalt, grass and soil. The tests are performed on an experimental platform. The result shows that the errors consist mainly of dropouts caused by overriding maximum speed, and of calibration error due to uneven ground. The number of dropouts can be reduced by limiting the maximum speed and detection of missing frames. The calibration problem can be solved using stereo cameras. This gives a height measurement and the calibration will be given by camera mounting. The algorithm using normalized cross-correlation shows the best result concerning number of dropouts, accuracy and calculation time.
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| 32. |
- Gu, Irene Yu-Hua, 1953, et al.
(author)
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Automatic Classification of Wood Defects using Support Vector Machines
- 2008
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In: Lecture Notes in Computer Science (including subseries Lecture Notes in Artificial Intelligence and Lecture Notes in Bioinformatics). - Berlin, Heidelberg : Springer Berlin Heidelberg. - 1611-3349 .- 0302-9743. - 3642023444 ; 5337, s. 356-367
-
Conference paper (peer-reviewed)abstract
- This paper addresses the issue of automatic wood defect classification. We propose a tree-structure support vector machine (SVM) to classify four types of wood knots by using images captured from lumber boards. Simple and effective features are proposed and extracted by first partitioning the knot images into 3 distinct areas, followed by applying an order statistic filter to yield an average pseudo color feature in each area. Excellent results have been obtained for the proposed SVM classifier that is trained by 800 wood knot images. Performance evaluation has shown that the proposed SVM classifier has resulted in an average classification rate of 96.5% and false alarm rate of 2.25% over 400 test knot images. Our future work includes more extensive tests on large data set and the extension of knot types.
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| 33. |
- Hansson, Andreas, et al.
(author)
-
Using Segmentation to Control the Retrieval of Data
- 2006
-
In: The 2006 IEEE International Joint Conference on Neural Network Proceedings. - : IEEE. - 0780394909 - 9780780394902 ; , s. 1764-1769
-
Conference paper (other academic/artistic)abstract
- One problem when storing sequential data using recurrent neural networks is that it is hard to preserve long term dependencies. Only the most recently stored data tend to be accurately recalled. One approach for reducing this recency effect has been to divide the data into segments and store the segments separately. This approach has provided promising results in prediction and classification domains. This paper analyzes in what way recall of the stored data is affected by segmentation. It is concluded that segmentation enables the control of which data that can be recalled. The problem of preserving long term dependencies in recurrent neural networks can therefore be reduced.
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| 34. |
- Khan, Zulfiqar Hasan, 1976, et al.
(author)
-
Joint Anisotropic Mean Shift and Consensus Point Feature Correspondences for Object Tracking in Video
- 2009
-
In: Proc. of IEEE International conf. on Multimedia and Expo. (ICME '09). ; , s. 1270-1273
-
Conference paper (peer-reviewed)abstract
- We propose a novel tracking scheme that jointly employs point feature correspondences and object appearance similarity. For selecting point correspondences, we use a subset of scale-invariant point features from SIFT that agree with a pre-defined affine transformation. The selected consensus points are then used for pre-selecting candidate regions. For appearance similarity based tracking, we employ an existing anisotropic mean shift, from which the formula for estimating bounding box parameters (width, height, orientation and center) are derived. A switching criterion is utilized to handle the situation where only a small number of point correspondences is found. Experiments and evaluation are performed on tracking moving objects on videos where objects may contain partial occlusions, intersection, deformation and pose changes among other transforms. Our comparisons with two existing methods have shown that the proposed scheme has yielded marked improvement, especially in terms of reducing tracking drifts, of robustness to occlusions, and of tightness and accuracy of tracked bounding box.
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| 35. |
- Khan, Zulfiqar Hasan, 1976, et al.
(author)
-
Joint particle filters and multi-mode anisotropic mean shift for robust tracking of video objects with partitioned areas
- 2009
-
In: IEEE international conf. on image processing (ICIP 2009). ; , s. 4077-4080
-
Conference paper (peer-reviewed)abstract
- We propose a novel scheme that jointly employs anisotropic mean shift and particle filters for tracking moving objects from video. The proposed anisotropic mean shift, that is applied to partitioned areas in a candidate object bounding box whose parameters (center, width, height and orientation) are adjusted during the mean shift iterations, seeks multiple local modes in spatial-kernel weighted color histograms. By using a Gaussian distributed Bhattacharyya distance as the likelihood and mean shift updated parameters as the state vector, particle filters become more efficient in terms of tracking using a small number of particles (
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| 36. |
- Kylberg, Gustaf, et al.
(author)
-
Towards Automated TEM for Virus Diagnostics : Segmentation of Grid Squares and Detection of Regions of Interest
- 2009
-
In: Proceedings of the 16th Scandinavian Conference on Image Analysis (SCIA). - Berlin : Springer-Verlag. - 9783642022296 ; , s. 169-178, s. 169-178
-
Conference paper (peer-reviewed)abstract
- When searching for viruses in an electron microscope thesample grid constitutes an enormous search area. Here, we present methodsfor automating the image acquisition process for an automatic virusdiagnostic application. The methods constitute a multi resolution approachwhere we first identify the grid squares and rate individual gridsquares based on content in a grid overview image and then detect regionsof interest in higher resolution images of good grid squares. Our methodsare designed to mimic the actions of a virus TEM expert manually navigatingthe microscope and they are also compared to the expert’s performance.Integrating the proposed methods with the microscope wouldreduce the search area by more than 99.99% and it would also removethe need for an expert to perform the virus search by the microscope.
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| 37. |
- Laptev, Ivan, et al.
(author)
-
Local velocity-adapted motion events for spatio-temporal recognition
- 2007
-
In: Computer Vision and Image Understanding. - : Elsevier. - 1077-3142 .- 1090-235X. ; 108:3, s. 207-229
-
Journal article (peer-reviewed)abstract
- In this paper, we address the problem of motion recognition using event-based local motion representations. We assume that similar patterns of motion contain similar events with consistent motion across image sequences. Using this assumption, we formulate the problem of motion recognition as a matching of corresponding events in image sequences. To enable the matching, we present and evaluate a set of motion descriptors that exploit the spatial and the temporal coherence of motion measurements between corresponding events in image sequences. As the motion measurements may depend on the relative motion of the camera, we also present a mechanism for local velocity adaptation of events and evaluate its influence when recognizing image sequences subjected to different camera motions. When recognizing motion patterns, we compare the performance of a nearest neighbor (NN) classifier with the performance of a support vector machine (SVM). We also compare event-based motion representations to motion representations in terms of global histograms. A systematic experimental evaluation on a large video database with human actions demonstrates that (i) local spatio-temporal image descriptors can be defined to carry important information of space-time events for subsequent recognition, and that (ii) local velocity adaptation is an important mechanism in situations when the relative motion between the camera and the interesting events in the scene is unknown. The particular advantage of event-based representations and velocity adaptation is further emphasized when recognizing human actions in unconstrained scenes with complex and non-stationary backgrounds.
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| 38. |
- Lindeberg, Tony, 1964-
(author)
-
Scale-Space
- 2009
-
In: Wiley Encyclopedia of Computer Science and Engineering. - Hoboken, New Jersey : John Wiley & Sons. ; , s. 2495-2504
-
Book chapter (peer-reviewed)abstract
- Scale-space theory is a framework for multiscale image representation, which has been developed by the computer vision community with complementary motivations from physics and biologic vision. The idea is to handle the multiscale nature of real-world objects, which implies that object may be perceived in different ways depending on the scale of observation. If one aims to develop automatic algorithms for interpreting images of unknown scenes, no way exists to know a priori what scales are relevant. Hence, the only reasonable approach is to consider representations at all scales simultaneously. From axiomatic derivations is has been shown that given the requirement that coarse-scale representations should correspond to true simplifications of fine scale structures, convolution with Gaussian kernels and Gaussian derivatives is singled out as a canonical class of image operators forthe earliest stages of visual processing. These image operators can be used as basis to solve a large variety of visual tasks, including feature detection, feature classification, stereo matching, motion descriptors, shape cues, and image-based recognition. By complementing scale-space representation with a module for automatic scale selection based on the maximization of normalized derivatives over scales, early visual modules can be made scale invariant. In this way, visual modules canadapt automatically to the unknown scale variations that may occur because of objects and substructures of varying physical size as well as objects with varying distances to the camera. An interesting similarity to biologic vision is that the scale-space operators resemble closely receptive field profiles registered in neurophysiologic studies of the mammalian retina and visual cortex.
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| 39. |
- Malm, Henrik, et al.
(author)
-
Adaptive enhancement and noise reduction in very low light-level video
- 2007
-
In: 11th International Conference on Computer Vision, 2007. - 1550-5499. - 9781424416318 ; , s. 1395-1402
-
Conference paper (peer-reviewed)abstract
- A general methodology for noise reduction and contrast enhancement in very noisy image data with low dynamic range is presented. Video footage recorded in very dim light is especially targeted. Smoothing kernels that automatically adapt to the local spatio-temporal intensity structure in the image sequences are constructed in order to preserve and enhance fine spatial detail and prevent motion blur. In color image data, the chromaticity is restored and demosaicing of raw RGB input data is performed simultaneously with the noise reduction. The method is very general, contains few user-defined parameters and has been developed for efficient parallel computation using a GPU. The technique has been applied to image sequences with various degrees of darkness and noise levels, and results from some of these tests, and comparisons to other methods, are presented. The present work has been inspired by research on vision in nocturnal animals, particularly the spatial and temporal visual summation that allows these animals to see in dim light.
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| 40. |
- Malmberg, Filip, 1980-, et al.
(author)
-
Sub-pixel Segmentation with the Image Foresting Transform
- 2009
-
In: Proceedings of International Workshop on Combinatorial Image Analysis. - Berlin, Heidelberg : Springer. - 9783642102080 ; 5852, s. 201-211
-
Conference paper (peer-reviewed)abstract
- The Image Foresting Transform (IFT) is a framework forimage partitioning, commonly used for interactive segmentation. Givenan image where a subset of the image elements (seed-points) have beenassigned user-defined labels, the IFT completes the labeling by computingminimal cost paths from all image elements to the seed-points. Eachimage element is then given the same label as the closest seed-point. Inits original form, the IFT produces crisp segmentations, i.e., each imageelement is assigned the label of exactly one seed-point. Here, we proposea modified version of the IFT that computes region boundaries withsub-pixel precision by allowing mixed labels at region boundaries. Wedemonstrate that the proposed sub-pixel IFT allows properties of thesegmented object to be measured with higher precision.
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| 41. |
- Niazi, Muhammad Khalid Khan, 1978-, et al.
(author)
-
Fully Automatic Heart Beat Rate Determination in Digital Video Recordings of Rat Embryos
- 2009
-
In: Transactions on Mass-Data Analysis of Images and Signals. - Leipzig, Germany : IBAI Publishing. - 1868-6451. ; 1:2, s. 132-146
-
Journal article (peer-reviewed)abstract
- Embryo cultures of rodents is an established technique for monitoring adverse effects of chemicals on embryonic development. The assessment involves determination of the heart rate of the embryo which is usually done visually, a technique which is tedious and error prone. We present a new method for fully automatic heart detection in digital videos of rat embryos. First it detects the heart location by using decimation free directional filter bank along with first absolute moment, and then it counts the number of heart beats for a predetermined period of time. Using this automated method many more embryos can be evaluated at reasonable cost.
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| 42. |
- Seipel, Stefan, et al.
(author)
-
Real-Time Rendering of Ice
- 2007
-
In: Proceedings of the Ninth IASTED International Conference on Computer Graphics and Imaging. - 9780889866447 ; , s. 60-66
-
Conference paper (peer-reviewed)abstract
- We present a method for implementing visual appearance of ice and its most important characteristics in real-time. The proposed method is capable of filling a given convex geometry with air particles and bubbles as well as adding an arbitrary amount of cracks. Techniques are presented for creating a bumpy and irregular surface that multiply reflects and refracts the environment. An improved image space technique for clipping a geometry using the Boolean difference of two geometries is presented as well. This technique is used on the cracks to clip them against the ice's geometry. The reflection and refraction effects on the ice are implemented by using environment mapping. Two-sided refraction is accomplished by combining the normal vectors of the front and back side of the ice object. The result is ice with convincing visual appearance rendered in real-time using modem graphics hardware.
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| 43. |
- Seipel, Stefan
(author)
-
Volumetric Normal Mapping in Rendering of Multivariate Volume Data
- 2007
-
In: Proceedings of EUROGRAPHICS 2007. ; , s. 49-52
-
Conference paper (peer-reviewed)abstract
- The work presented in this paper introduces volumetric normal maps for producing visual structure in directvolume rendering (DVR) of 3D data for the purpose of visualizing multiple attributes in a 3D volume. We usevolumetric normal maps to represent normal vector glyphs that are subsequently applied to warp the gradients inthe primary volume data. This method is intended to visualize some secondary attribute in DVR. We demonstratethat our method can render visual structures in DVR without the need of explicit surface reconstruction andtexturing.
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| 44. |
- Sladoje, Natasa, et al.
(author)
-
High-precision boundary length estimation by utilizing gray-level information
- 2009
-
In: IEEE Transactions on Pattern Analysis and Machine Intelligence. - 0162-8828 .- 1939-3539. ; 31:2, s. 357-363
-
Journal article (peer-reviewed)abstract
- We present a novel method that provides an accurate and precise estimate of the length of the boundary (perimeter) of an object by taking into account gray levels on the boundary of the digitization of the same object. Assuming a model where pixel intensity is proportional to the coverage of a pixel, we show that the presented method provides error-free measurements of the length of straight boundary segments in the case of nonquantized pixel values. For a more realistic situation, where pixel values are quantized, we derive optimal estimates that minimize the maximal estimation error. We show that the estimate converges toward a correct value as the number of gray levels tends toward infinity. The method is easy to implement; we provide the complete pseudocode. Since the method utilizes only a small neighborhood, it is very easy to parallelize. We evaluate the estimator on a set of concave and convex shapes with known perimeters, digitized at increasing resolution. In addition, we provide an example of applicability of the method on real images, by suggesting appropriate preprocessing steps and presenting results of a comparison of the suggested method with other local approaches.
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| 45. |
- Sladoje, Natasa, et al.
(author)
-
Pixel Coverage Segmentation for Improved Feature Estimation
- 2009
-
In: 15th International Conference on Image Analysis and Processing. - Berlin / Heidelberg : Springer. - 9783642041457 ; 5716, s. 929-938
-
Conference paper (peer-reviewed)abstract
- By utilizing intensity information available in images, partial coverage of pixels at object borders can be estimated. Such information can, in turn, provide more precise feature estimates. We present a pixel coverage segmentation method which assigns pixel values corresponding to the area of a pixel that is covered by the imaged object(s). Starting from any suitable crisp segmentation, we extract a one-pixel thin 4-connected boundary between the observed image components where a local linear mixture model is used for estimating fractional pixel coverage values. We evaluate the presented segmentation method, as well as its usefulness for subsequent precise feature estimation, on synthetic test objects with increasing levels of noise added. We conclude that for reasonable noise levels the presented method outperforms the achievable results of a perfect crisp segmentation. Finally, we illustrate the application of the suggested method on a real histological colour image.
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| 46. |
|
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| 47. |
- Strand, Robin, et al.
(author)
-
Topology preserving marching cubes-like algorithms on the face-centered cubic grid
- 2007
-
In: 14TH INTERNATIONAL CONFERENCE ON IMAGE ANALYSIS AND PROCESSING, PROCEEDINGS. - LOS ALAMITOS : IEEE COMPUTER SOC. - 9780769528779 - 0769528775 ; , s. 781-786
-
Conference paper (other academic/artistic)abstract
- The well-known marching cubes algorithm is modified to apply to the face-centered cubic (fcc) grid. Thus, the local configurations that are considered when extracting the local surface patches are not cubic anymore. This paper presents three different partitionings of the fcc grid to be used for the local configurations. The three candidates are evaluated theoretically and experimentally and compared with the original marching cubes algorithm. It is proved that the reconstructed surface is topologically equivalent to the surface of the original object when the surface of the original object that is digitized is smooth and a sufficiently dense fcc grid is used.
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| 48. |
- Strandmark, Petter, et al.
(author)
-
Joint Random Sample Consensus and Multiple Motion Models for Robust Video Tracking
- 2009
-
In: Lecture Notes in Computer Science. - Berlin, Heidelberg : Springer Berlin Heidelberg. - 1611-3349 .- 0302-9743. ; 5575/2009, s. 450-459:5575, s. 450-459
-
Conference paper (peer-reviewed)abstract
- We present a novel method for tracking multiple objects in video captured by a non-stationary camera. For low quality video, RANSAC estimation fails when the number of good matches shrinks below the minimum required to estimate the motion model. This paper extends RANSAC in the following ways: (a) Allowing multiple models of different complexity to be chosen at random; (b) Introducing a conditional probability to measure the suitability of each transformation candidate, given the object locations in previous frames; (c) Determining the best suitable transformation by the number of consensus points, the probability and the model complexity. Our experimental results have shown that the proposed estimation method better handles video of low quality and that it is able to track deformable objects with pose changes, occlusions, motion blur and overlap. We also show that using multiple models of increasing complexity is more effective than just using RANSAC with the complex model only.
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| 49. |
- Svensson, Björn, et al.
(author)
-
On Geometric Transformations of Local Structure Tensors
- 2009. - 1
-
In: Tensors in Image Processing and Computer Vision. - London : Springer. - 9781848822986 - 9781848822993 ; , s. 179-193
-
Book chapter (other academic/artistic)abstract
- The structure of images has been studied for decades and the use of local structure tensor fields appeared during the eighties [3, 14, 6, 9, 11]. Since then numerous varieties of tensors and estimation schemes have been developed. Tensors have for instance been used to represent orientation [7], velocity, curvature [2] and diffusion [19] with applications to adaptive filtering [8], motion analysis [10] and segmentation [17]. Even though sampling in non-Cartesian coordinate system are common, analysis and processing of local structure tensor fields in such systems is less developed. Previous work on local structure in non-Cartesian coordinate systems include [21, 16, 1, 18].
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| 50. |
- Tanács, Attila, et al.
(author)
-
Recovering Affine Deformations of Fuzzy Shapes
- 2009
-
In: 16th Scandinavian Conference on Image Analysis. - Berlin / Heidelberg : Springer. - 9783642022296 ; , s. 735-744, s. 735-744
-
Conference paper (peer-reviewed)abstract
- Fuzzy sets and fuzzy techniques are attracting increasing attention nowadays in the field of image processing and analysis. It has been shown that the information preserved by using fuzzy representation based on area coverage may be successfully utilized to improve precision and accuracy of several shape descriptors; geometric moments of a shape are among them. We propose to extend an existing binary shape matching method to take advantage of fuzzy object representation. The result of a synthetic test show that fuzzy representation yields smaller registration errors in average. A segmentation method is also presented to generate fuzzy segmentations of real images. The applicability of the proposed methods is demonstrated on real X-ray images of hip replacement implants.
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