Previous work on estimating the epipolar geometry of two views relies on being able to reliably match feature points based on appearance. In this paper, we go one step further and show that it is feasible to compute both the epipolar geometry and the correspondences at the same time based on geometry only. We do this in a globally optimal manner. Our approach is based on an efficient branch and bound technique in combination with bipartite matching to solve the correspondence problem. We rely on several recent works to obtain good bounding functions to battle the combinatorial explosion of possible matchings. It is experimentally demonstrated that more difficult cases can be handled and that more inlier correspondences can be obtained by being less restrictive in the matching phase.

Outliers pose a problem in all real structure from motion systems. Due to the use of automatic matching methods one has to expect that a (sometimes very large) portion of the detected correspondences can be incorrect. In this paper we propose a method that estimates the relative translation between two cameras and simultaneously maximizes the number of inlier correspondences. Traditionally, outlier removal tasks have been addressed using RANSAC approaches. However, these are random in nature and offer no guarantees of finding a good solution. If the amount of mismatches is large, the approach becomes costly because of the need to evaluate a large number of random samples. In contrast, our approach is based on the branch and bound methodology which guarantees that an optimal solution will be found. While most optimal methods trade speed for optimality, the proposed algorithm has competitive running times on problem sizes well beyond what is common in practice. Experiments on both real and synthetic data show that the method outperforms state-of-the-art alternatives, including RANSAC, in terms of solution quality. In addition, the approach is shown to be faster than RANSAC in settings with a large amount of outliers.

In this paper we explore the use of a mobile video-conferencing tool (MVCT) in advanced home care of children. We present the results from a qualitative study where we have evaluated mobile video communication between the patient's home and the hospital unit. Our results show that mobile video enhances communication between home care teams and medical staff at the unit, makes more effective use of practitioners' time and that the equipment have additional values for staff that extend beyond video communication. Challenges identified are related to technical problems, limitations in the MVCT's design and the concern that the inability to handle problems may affect health care professionals' role as an authority. The benefits of the MVCT rely to a great extent on individual users' creativity and the willingness of key actors in the organization's management to find ways of improving the present home care format.

It has long been recognized that one of the fundamental difficulties in the estimation of two-view epipolar geometry is the capability of handling outliers. In this paper, we develop a fast and tractable algorithm that maximizes the number of inlier under the assumption of a purely translating camera. Compared to classical random sampling methods, our approach is guaranteed to compute the optimal solution of a cost function based on reprojection errors and it has better time complexity. The performance is in fact independent of the inlier/outlier ratio of the data. This opens up for a more reliable approach to robust ego-motion estimation. Our basic translation estimator can be embedded into a system that computes the full camera rotation. We demonstrate the applicability in several difficult settings with large amounts of outliers. It turns out to be particularly well-suited for small rotations and rotations around a known axis (which is the case for cellular phones where the gravitation axis can be measured). Experimental results show that compared to standard RANSAC methods based on minimal solvers, our algorithm produces more accurate estimates in the presence of large outlier ratios.

Feature content of modern mobile devices is increasing rapidly, followed by a soaring power consumption. We are forced to optimize for power consumption, which impacts design at both hardware and software level. The complexity of the problem increases when considering event driven real time systems where the CPU speed can affect temporal validity. We present an industrial implementation of a real time power aware scheduling algorithm on the Enea OSE operating system. Even sporadic tasks and workloads up to 100% can be scheduled, with significant power saving results. An additional run time mode is also introduced with reduced quality of service towards soft real time tasks, but without jeopardizing hard real time deadlines and further suppressing power consumption in battery critical situations.

A Worst-Case Execution Time (WCET) analysis derives upper bounds for execution times of programs. Such bounds are crucial when designing and verifying real-time systems. A major problem with todaypsilas WCET analysis approaches is that there is no feedback on the particular values of the input variables that cause the programpsilas WCET. However, this is important information for the real-time system developer.We present a novel approach to overcome this problem. In particular, we present a method, based on a combination of input sensitive static WCET analysis and systematic search over the value space of the input variables, to derive the input value combination that causes the WCET. We also present several different approaches to speed up the search. Our evaluations show that the WCET input values can be relatively quickly derived for many type of programs, even for program with large input value spaces. We also show that the WCET estimates derived using the WCET input values often are much tighter than the WCET estimates derived when all possible input value combinations are taken into account.

We present a contract-based technique to achieve reuse of known worst-case execution times (WCET) in conjunction with reuse of software components. For resource constrained systems, or systems where high degree of predictability is needed, classical techniques for WCET- estimation will result in unacceptable overestimation of the execution-time of reusable software components with rich behavior. Our technique allows different WCETs to be associated with subsets of the component behavior. The appropriate WCET for any usage context of the component is selected be means of component contracts over the input domain. In a case-study we illustrate our technique and demonstrate its potential in achieving tight WCET- estimates for reusable components with rich behavior.

The use of component-based development (CBD) is growing in the software engineering community and it has been successfully applied in many engineering domains such as office applications and in web-based distributed applications. Recently, the need of CBD is growing also in other domains related to dependable and embedded systems, namely, in the control engineering domain. However, the widely used commercial component technologies are unable to provide solutions to the requirements of embedded systems as they require too much resources and they do not provide methods and tools for developing predictable and analyzable embedded systems. There is a need for new component-based technologies appropriate to development of embedded systems. In this paper we briefly present a component-based development framework called SAVEComp. SAVEComp is developed for safety-critical real-time systems. One of the main characteristics of SAVEComp is syntactic and semantic simplicity which enables a high analyzability of properties important for embedded systems. We discuss how SAVEComp is able to provide an efficient support for designing and implementing embedded control systems by mainly focusing on simplicity and analyzability of functional requirements and of real-time and dependability quality attributes. In particular we discuss the typical solutions of control systems in which feedback loops are used and which significantly complicate the design process. We provide a solution for increasing design abstraction level and still being able to reason about system properties using SAVEComp approach. Finally, we discuss an extension of SAVEComp with dynamic run-time property checking by utilizing run-time spare capacity that is normally induced by real-time analysis.