Catálogo de publicaciones - libros

We attempt to show that a tessellated spatial model has definite advantages for cartographic applications, and facilitates a kinetic structure for map updating and simulation. We develop the moving-point Delaunay/Voronoi model that manages collision detection snapping and intersection at the data input stage by maintaining a topology based on a complete tessellation. We show that the Constrained Delaunay triangulation allows the simulation of edges, and not just points, with only minor changes to the moving-point model. We then develop an improved kinetic Line-segment Voronoi diagram, which is a better-specified model of the spatial relationships for compound map objects than is the Constrained Triangulation. However, until now it has been more difficult to implement. We believe that this method is now viable for 2D cartography, and in many cases it should replace the Constrained approach. Whichever method is used, the concept of using the moving point as a pen, with the ability to delete and add line segments as desired in the construction and updating process, appears to be a valuable development.

Maps are a fundamental spatial concept capable of representing and storing large amounts of information in a visual form. Map operations have been studied and rigorously defined in the literature; however, we identify a new class of operations which cannot be completed using existing operations. We then consider existing operations involving connectivity concepts, and extend this class of operations by defining new, more complex operations that take advantage of the connectivity properties of maps.

The Tangible Augmented Street Map (TASM) is a novel interface to geographic objects, such as tiled maps of labeled city streets. TASM uses tangible Augmented Reality, the superimposition of digital graphics on top of real world objects in order to enhance the user’s experience. The tangible object (i.e. a cube) replicates the role of an input device. Hence the cube can be rotated to display maps that are adjacent to the current tile in geographic space. The cube is capable of theoretically infinite movement, embedded in a coordinate system with topology enabled. TASM has been tested for usability using heuristic evaluation, where selected experts use the cube, establishing non-correspondence with recognized usability principles. While general and vague, the heuristics helped prioritize immediate geographic and system-based tasks needed to improve the usability of TASM, also pointing the way towards a group of geographically oriented heuristics. This addresses a key geovisualization challenge — the creation of domain-specific and technology-related theory.

In [], the first two authors of this paper presented the first algorithms to construct rectangular cartograms. The first step is to determine a representation of all regions by rectangles and the second — most important — step is to get the areas of all rectangles correct. This paper presents a new approach to the second step. It is based on alternatingly solving linear programs on the -coordinates and the -coordinates of the sides of the rectangles. Our algorithm gives cartograms with considerably lower error and better visual qualities than previous approaches. It also handles countries that cannot be present in any purely rectangular cartogram and it introduces a new way of controlling incorrect adjacencies of countries. Our implementation computes aesthetically pleasing rectangular and nearly rectangular cartograms, for instance depicting the 152 countries of the World that have population over one million.

Elements of urban terrain models such as streets, pavements, lawns, walls, and fences are fundamental for effective recognition and convincing appearance of virtual 3D cities and virtual 3D landscapes. These elements complement important other components such as 3D building models and 3D vegetation models. This paper introduces an object-oriented, rule-based and heuristic-based approach for modeling detailed virtual 3D terrains in an automated way. Terrain models are derived from 2D vector-based plans based on generation rules, which can be controlled by attributes assigned to 2D vector elements. The individual parts of the resulting urban terrain models are represented as “first-class” objects. These objects remain linked to the underlying 2D vector-based plan elements and, therefore, preserve data semantics and associated thematic information.

With urban terrain models, we can achieve high-quality photorealistic 3D geovirtual environments and support interactive creation and manipulation. The automated construction represents a systematic solution for the bi-directional linkage of 2D plans and 3D geovirtual environments and overcomes cost-intensive CAD-based construction processes. The approach both simplifies the geometric construction of detailed urban terrain models and provides a seamless integration into traditional GIS-based workflows.

The resulting 3D geovirtual environments are well suited for a variety of applications including urban and open-space planning, information systems for tourism and marketing, and navigation systems. As a case study, we demonstrate our approach applied to an urban development area of downtown Potsdam, Germany.

In this paper we describe a novel, extensible visualization system currently under development at Aston University. We introduce modern programming methods, such as the use of data driven programming, design patterns, and the careful definition of interfaces to allow easy extension using plug-ins, to 3D landscape visualization software. We combine this with modern developments in computer graphics, such as vertex and fragment shaders, to create an extremely flexible, extensible real-time near photorealistic visualization system. In this paper we show the design of the system and the main sub-components. We stress the role of modern programming practices and illustrate the benefits these bring to 3D visualization.

Topographic features such as physical objects become more complex due to increasing multiple land use. Increasing awareness of the importance of sustainable (urban) development leads to the need for 3D planning and analysis. As a result, topographic products need to be extended into the third dimension. In this paper, we developed a new topological 3D data model that relies on Poincaré algebra. The internal structure is based on a network of simplexes, which are well defined, and very suitable for keeping the 3D data set consistent. More complex 3D features are based on this simple structure and computed when needed. We describe an implementation of this 3D model on a commercial DBMS. We also show how a 2D visualizer can be extended to visualize these 3D objects.

This paper introduces a new approach to 3D handling of geographical information in the context of risk analysis. We propose to combine several geometrical and topological models for 3D data to take advantage from their respective capabilities. Besides, we adapt from crystallography a high-level description of geographical features that enables to compute several metric and cardinal relations, such as the “lay on” relation, which plays a key-role for geographical information.

For the generalization of river network, the importance decision of river channels in a catchment has to consider three aspects at different levels: the spatial distribution pattern at macro level, the distribution density at meso level and the individual geometric properties at micro level. To extract such structured information, this study builds the model of watershed hierarchical partitioning based on Delaunay triangulation. The watershed area is determined by the spatial competition process applying the partitioning similar to Voronoi diagram to obtain the basin polygon of each river channel. The hierarchical relation is constructed to represent the inclusion between different level watersheds. This model supports to compute the parameters such as distribution density, distance between neighbor channels and the hierarchical watershed area. The study presents a method to select the river network by the watershed area threshold. The experiment on real river data shows this method has good generalization effect.

In this paper the detection and typification of grid structures in building groups is described. Typification is a generalization operation that replaces a large number of similar objects by a smaller number of objects, while preserving the global structure of the object distribution. The typification approach is based on three processes. First the grid structures are detected based on the so-called . Second the detected grid structures are regularized by a least square adjustment of an affine or Helmert transformation. The third process is the reduction or simplification of the grid structure, which can be done using the same affine or Helmert transformation approach.