gvSOS: a new client for the OGC® Sensor Obseration Service Interface standard

A key problem with sensor networks is achieving interoperability between different networks potentially built using different software and hardware platforms. Services interfaced by the Open Geospatial Consortium (OGC) specifications allow GIS clients to access geospatial data without knowing the details about how these data are gathered or stored. Currently, OGC is working on a set of interoperable interfaces and metadata encodings known as Sensor Web Enablement (SWE) that enables the integration of heterogeneous sensor systems and measurements into geospatial information infrastructures. In this article we present the implementation of gvSOS, a new module for gvSIG to connect to Sensor Observation Services (SOS). The gvSOS client module allows gvSIG users to interact with SOS servers, displaying the information gathered by sensors as a layer composed by features. We present the software engineering development process followed to build the module. For each step of the process we specify the main obstacles found during the development such as restrictions of the gvSIG architecture, inaccuracies in the OGC specifications, and a set of common problems found in current SOS server implementations available on the Internet. For most of the problems found we propose a solution, or at least we present a path that might lead to i

User-assisted simplification method for triangle meshes preserving boundaries

This paper proposes a user-assisted mesh simplification method applied to CAD models converted to triangle meshes. This work offers the possibility of simplifying each subobject independently and at different levels of detail. This way, the user can simplify the whole model and then modify some parts, by simplifying more or by refining the desired subobjects. This can be performed while the total number of triangles in the simplified model is maintained. In this method any error metric based on an edge collapse operation can be used. Boundaries between subobjects are preserved and important attributes in the final aspect of simplified models, like normals and texture coordinates, are also considered. © 2009 Elsevier Ltd. All rights reserved

Improving data fusion in personal positioning systems for outdoor environments

A fault detection and correction methodology for personal positioning systems for outdoor environments is presented. We demonstrate its successful use in a system consisting of a global positioning system receiver and an inertial measurement unit. Localization is based on the dead reckoning algorithm. In order to obtain more reliable information from data fusion, which is carried out with Kalman filtering, the proposed methodology involves: (1) evaluation of the information provided by the sensors and (2) adaptability of the filtering. By carefully analyzing these factors we accomplish fault detection in different sources of information and in filtering. This allows us to apply corrections whenever the system requires it. Hence, our methodology consists of two stages. In the first stage, the evaluation is conducted. We apply the principles of causal diagnosis using possibility theory by defining states for normal behavior and for fault states. When a fault occurs, corrective measures are applied according to empirical knowledge. In the second stage, the consistency test of the filtering is performed. If this is inconsistent, principles of adaptive Kalman filtering are applied, which means the process and measurement noise matrices are tuned. Our results indicate a reasonable improvement of the trajectory obtained. At the same time, we can achieve consistent filtering, to obtain a more robust system and reliable information

Developing a virtual trade fair using an agent-oriented approach

Online virtual trade fairs are becoming a popular way of establishing economic trade relationships nowadays. In the current context of the world economy, new ways of creating virtual environments where suppliers can show their products to potential customers are increasingly in demand. Some people can be found in this kind of scenario representing a role such as, for example, the administrator, the customers or the suppliers. The interaction between them is one of the most important characteristics of these commercial environments. Taking all these concepts into account, this article presents a 3D virtual trade fair that has been defined using an agent-oriented approach. This approach makes it possible to model, understand and implement the virtual economic environment, where interaction is the norm. Moreover, it makes it easy to add new components and meet new requirements in order to develop an open architecture that continuously changes and evolves. In this virtual trade fair, the chosen methodology has been Gaia, widely used for agent-oriented analysis and design of multi-agent systems