View-based Framework Research Articles

A fast object registration method for augmented reality assembly with simultaneous determination of multiple 2D-3D correspondences

Abstract A fast and robust object registration is one of the fundamental steps of an augmented reality (AR) assembly guidance system. To manage the registration of texture-less objects from monocular images, this paper presents a three-dimensional (3D) object registration solution in the view-based framework, which incorporates a new image feature named as chain-of-lines feature (COLF). The COLF, constructed by several directed line segments with geometric constraints, enhances the robustness of the registration by establishing multiple correspondences between the two-dimensional (2D) image and 3D model simultaneously. In order to save on computational cost and improve the efficiency of the COLF-based registration, a compression algorithm based on the local breadth-first search (LBFS) strategy is also proposed; this adaptively reduces the number of keyframes according to the target model. In the experimental evaluation, the combination of COLF and LBFS-based keyframe compression shows higher registration success rate and faster speed in comparison with conventional registration methods. Moreover, an AR assembly guidance prototype system for reductors is introduced to illustrate the application of the proposed registration method.

A View-based Approach to Quality of Service Modelling in Service-oriented Enterprise Systems

Service-oriented enterprise architecture and emerging advanced technologies bring up new problems for enterprise systems engineering or, more exactly, for service-oriented enterprise systems (SoESs) engineering. One of the most important issues is the modelling of quality of services (QoS). The QoS is a complex and multi-sided concept. In various contexts and for different aims it may be defined quite differently. In the context of SoES, QoS has also some specifics that in several aspects differ from the systems implementing service-oriented architecture (SOA) in other contexts, for example, in business-to-consumer or utility-service ones. The paper suggests that it is possible to identify several understandings of QoS reflecting the viewpoints of different SoES stakeholders in a similar way as it is carried out for software products. It also proposes a conceptual view-based framework for QoS modelling in web-based SoES and for balancing different viewpoints.

Navigation and acquisition of spatial knowledge in a virtual maze.

Spatial behavior in humans and animals includes a wide variety of behavioral competences and makes use of a large number of sensory cues. Here we studied the ability of human subjects to search locations, to find shortcuts and novel paths, to estimate distances between remembered places, and to draw sketch maps of the explored environment; these competences are related to goal-independent memory of space, or cognitive maps. Information on spatial relations was restricted to two types: a visual motion sequence generated by simulated movements in a virtual maze and the subject's own movement decisions defining the path through the maze. Visual information was local (i.e., no global landmarks or compass information was provided). Other position and movement information (vestibular or proprioceptive) was excluded. The amount of visual information provided was varied over four experimental conditions. The results indicate that human subjects are able to learn a virtual maze from sequences of local views and movements. The information acquired is local, consisting of recognized positions and movement decisions associated to them. Although simple associations of this type can be shown to be present in some subjects, more complete configurational knowledge is acquired as well. The results are discussed in a view-based framework of navigation and the representation of spatial knowledge by means of a view graph.