Vernieuwde master 'Geomatics for the built environment

OTB ResearchOTB Research Institute for the Built Environmen

Delauney tetrahedralizations: Honor degenerated cases

The definition of a Delaunay tetrahedralization (DT) of a set S of points is well known: a DT is a tetrahedralization of S in which every simplex (tetrahedron, triangle, or edge) is Delaunay. A simplex is Delaunay if all of its vertices can be connected by a circumsphere that encloses no other vertex. An important remark made in virtually all papers on this topic is that “although any number of vertices is permitted on the sphere”, a Delaunay tetrahedralization is unique “only if the points are in general position, which is the absence of degeneracy (i.e., five or more vertices possible on the circumsphere)”. For applications in which the DT must be unique and invariant invariable under either geometrical rotation or the numbering of the points of set S, degenerated cases are expected to be resolved or at least indicated. This research, however, will direct to a method in which degenerated cases are not solved by a geometrically distorted set of input data using Steiner Points, nor is just one of the possible ‘unique’ DTs generated. To the contrary, an extra type of ‘non-geometrical’, flat, zero-volume ‘tetrahedra’ is purposely introduced in order to indicate the degenerated cases within the applied data structure of the tetrahedralization. The four vertices of these flat tetrahedra lie on the same circumsphere as the vertices of their neighboring tetrahedra. Once the set S of points is tetrahedralized, these flat tetrahedra provide a tool with which to discover other ‘unique’ DTs of the set S of points. From this set of unique DTs, the one having a global optimum can be selected for a given purpose, e.g. to support datadependent applications. Another benefit in creating flat tetrahedra is the ability to indicate nearly degenerated cases, eliminating the need for exact arithmetic.OTB onderzoekOTB Research Institute for the Built Environmen

Localization with Wi-fi fingerprinting: Towards indoor navigation on smartphones

GIS TechnologyOTB Research Institute for the Built Environmen

Indoor Signposting and Wayfinding through an Adaptation of the Dutch Cyclist Junction Network System

Finding's ones way in complex indoor settings can be a quite stressful and time-consuming task, especially for users unfamiliar with the environment. There have been developed several different approaches to provide wayfinding assistance in order to guide a person from a starting point to a destination but none of them has emerged to be efficient enough in order to act as a uniform solution. Moreover, referencing to landmarks is not widely employed by wayfinding assistance systems despite the fact that landmark-based navigation is the most natural way for people to navigate through unfamiliar environments. In this paper, a new wayfinding method for indoor environments is proposed, which makes use of the landmark concept. The method to achieve it is by translating the main principles of an already existing outdoor wayfinding system which applies successfully for the case of cyclists in The Netherlands. The first step is to define the locations, i.e. decision points, where wayfinding assistance is needed in indoor settings and secondly, to supply them with a special type of landmark which will be in the form of signpost, which provides all the necessary information. A graph based representation of the indoor setting is generated in order to extract the decision points and create the network of all possible routes in the environment.Architecture and The Built Environmen

Exploratieve Puntenwolken

Dit ‘vliegende startproject’ is uitgevoerd in opdracht van: de Raamovereenkomst Rijkswaterstaat – TU DelftOTBArchitecture and The Built Environmen