Lars Bodum

Using 3D in Visualization

Publisher Summary This chapter addresses the role of three-dimensionality used in both the process of visualization and more specifically in the representation of 3D objects and space. It also provides a brief characterization of 3D visual representations and presents some examples of 3D visualizations. The mutual influence and impact of 3D visualization, technology, and theory is also discussed. Three-dimensionality as a central and challenging phenomenon is used by an increasing number of visualization applications and systems. However, there is still too little known about the time appropriate to do so and the way 3D can be used in visualization most effectively. The term “3D” may be taken to refer to the dimensionality of the raw data that forms the basis of the visualization process. There are manifold implications of 3D in visualizations with respect to expressiveness, effectiveness, and appropriateness. For example, the generation of geological borehole data, or the vertical and planimetric measurement of atmospheric temperature and wind speeds can all be considered 3D. However, the dimensionality of raw data need not be limited to spatial quantities.

GRIFINOR: Integrated Object-Oriented Solution for Navigating Real-Time 3D Virtual Environments

The ability to navigate a 3d virtual environment in real-time has a high priority in connection with different applications for disaster management. This paper presents GRIFINOR — a platform for applications within this area. As a part of GRIFINOR, three new innovations have been promoted. They are presented in this paper as well. In many situations it is important that geoinformation can be accessible for queries within a very short time-frame (minutes). Questions about spatial reasoning and volumetric calculations in connection with different types of simulation has been very dependent on a priori models and very fast computer graphics hardware and software. It is also essential that the features of the model become real objects with attributes etc. Urban 3d models have traditionally been built as wire frame models. This makes it very difficult and in some situations impossible to attach geoinformation to the spatial structure in a way so that it is useful for real-time navigation in 3d. These wire frame models are not suitable for either a connection to a spatial database or for spatial queries. Centre for 3D GeoInformation at Aalborg University, is developing a system that handles 3D data structures as objects with facilities to support real-time geovisualization. The need for a new concept in this area has been one of the major motivations for the development of GRIFINOR. Instead of dealing with simple geometry in a CAD-based environment, GRIFINOR is developed to support object-oriented technology.

Modelling Virtual Environments for Geovisualization: A Focus on Representation

The use of virtual environments in geovisualization has become a major topic within the last few years. The main reason for this interest is the growing use of 3D models and visual realizations of these representations in a wide range of applications concerned with the geographic element of information. The implementation and use of virtual environments has developed from being a rather sophisticated type of visualization that demanded extreme computer resources to become an integral part of the software on every desktop computer. This chapter addresses both philosophical and technical issues regarding the modelling of virtual environments. It specifically focuses on the different representational aspects to be taken into consideration when a virtual environment is created. These aspects are data modelling, 3D modelling and level-of-detail. A range of different approaches can be taken to visualize a virtual environment within the geographic domain. A categorization of the virtual environments is offered through which the differences between them are highlighted. It is possible to achieve this categorization in many ways and from many perspectives since this is not and will not be research of a purely positivistic nature. The two variables used for the categorization in this chapter are level of abstraction and the temporal characteristic of the model.

Mapping virtual worlds

Metaphors from traditional cartography are very appropriate when constructing and documenting virtual worlds. But it is also a question about developing new methods for multi-dimensional and dynamic mapping of virtual worlds as means for navigationa and way finding.

Managed Objects for Infrastructure Data

Using data objects to describe features in the real world is a new idea and several approaches have already been shown to match scientific paradigms exceedingly well [1, 2, 3]. Depending on the required level of abstraction, it is possible to represent the world more or less closely to reality. In the realm of 3D Geoinformation research, this realism is often related to the way the spatial world is represented. By contrast, the 2D GIS community focuses on attribute data that describes additional states or characteristics of a feature. The main focus in 3D Geoinformation has always been on the representation of spatial objects, on relations like topology, ontology, and on storing and presenting them with more or less detail. The Centre for 3D GeoInformation (3DGI) at Aalborg University is currently participating in a project that explores objects that will not only contain geometry and associated attributive data but also will contain behavioural information. Our goal is to communicate the design and handling of these enhanced objects by means of the concept introduced in Java whereby objects are created in bytecode and subsequently executed within a Java virtual machine. This concept has already been implemented in the GRIFINOR (http://www.grifinor.net) platform [4]. This article will present the core ideas of relevance to this concept as it relates to current understanding of objects. Our work also offers suggestions on how to implemented such algorithms using real-life infrastructure data. Furthermore, we elaborate on the possibilities and challenges associated with moving from mostly static objects to dynamic objects in the area of 3D geoinformation.

Modelling Virtual Environments for Geovisualization

The use of virtual environments in geovisualization has become a major topic within the last few years. The main reason for this interest is the growing use of 3D models and visual realizations of these representations in a wide range of applications concerned with the geographic element of information. The implementation and use of virtual environments has developed from being a rather sophisticated type of visualization that demanded extreme computer resources to become an integral part of the software on every desktop computer. This chapter addresses both philosophical and technical issues regarding the modelling of virtual environments. It specifically focuses on the different representational aspects to be taken into consideration when a virtual environment is created. These aspects are data modelling, 3D modelling and level-of-detail. A range of different approaches can be taken to visualize a virtual environment within the geographic domain. A categorization of the virtual environments is offered through which the differences between them are highlighted. It is possible to achieve this categorization in many ways and from many perspectives since this is not and will not be research of a purely positivistic nature. The two variables used for the categorization in this chapter are level of abstraction and the temporal characteristic of the model.

3D Geo-Information Sciences

Keynotes.- A Virtual Geographic Environment for a Simulation of Air Pollution Dispersion in the Pearl River Delta (PRD) Region.- Representing and Exchanging 3D City Models with CityGML.- Research and Development Program for the Third National Geographic Information System Project in Korea: Korean Land Spatialization Program.- Papers.- Construction Operators for Modelling 3D Objects and Dual Navigation Structures.- A Multilayered Space-Event Model for Navigation in Indoor Spaces.- Towards Defining a Framework for Automatic Generation of Buildings in CityGML Using Building Information Models.- Managed Objects for Infrastructure Data.- Integrating Terrain Surface and Street Network for 3D Routing.- Using a B-Rep Structure to Query 9-Intersection Topological Relationships in 3D GIS - Reviewing the Approach and Improving Performance.- Query Processing in 3D Spatial Databases: Experiences with Oracle Spatial 11g.- Making Interoperability Persistent: A 3D Geo Database Based on CityGML.- Use of Finite Arithmetic in 3D Spatial Databases.- Automatic Digital Aerial Image Resection Controlled by LIDAR Data.- Automatic Surface Patch Generation from a Video Image Sequence.- Indoor 3D Modeling and Visualization with a 3D Terrestrial Laser Scanner.- Automatic Image Mosaic-Building Algorithm for Generating Facade Textures.- 3D Continuous K-NN Query for a Landmark-based Wayfinding Location-based Service.- 3D Geo-Network for Agent-based Building Evacuation Simulation.- Hierarchical Modelling of Multi-Geospatial Databases as Basis for Geo-Oriented 3D Analysis Capabilities.- Solar Radiation over the Urban Texture: LIDAR Data and Image Processing Techniques for Environmental Analysis at City Scale.- Creation and Error Analysis of High Resolution DEM Based on Source Data Sets of Various Accuracy.- A Topological Analysis Method for 3D Geo-Entities Structured as Hexahedron Tessellations.- Constraint-based Generation and Visualization of 3D City Models.- GeoVEs as Tools to Communicate in Urban Projects: Requirements for Functionality and Visualization.- Producing 3D Applications for Urban Planning by Integrating 3D Scanned Building Data with Geo-spatial Data.- 3D Dynamic Simulation and Visualization for GIS-based Infiltration Excess Overland Flow Modelling.A complete methodology from the extraction of Light Detection and Ranging (LIDAR) data to the environmental analysis of urban models and the visualization of results is presented. Aim of t he work is to establish a process to investigate digital urban models integra ting cross-disciplinary competences, like remote sensing, GIS, image proces sing and urban and environmental studies. Toward this goal, working on several interfaces, tools and datasets was necessary to provide a conse quent structure to the introduced methodology. Case study for application was a squared area 300 m etres wide in central Geneva where LIDAR data are available. The us of a hybrid approach from raw LIDAR data and vectorial digital maps (GIS data) of buildings footprints for the interpolation of a 2.5 -D urban surface model, with a resolution grid of 0.50 by 0.50 metres, allo wed to refine vertical

Design Issues to be Considered for Development of an Object-Oriented System for 3D Geovisualization: The Aalborg Experience

The Center for 3D GeoInformation at Aalborg University (DK) became a reality in 2001. Among the many activities in the center, there is one that goes through all the others as an important red line. That is the development of a general object-oriented system for real-time 3D visualization of geographically based Virtual Environments, called GRIFINOR. This paper will reveal some of the considerations and aspects that have been discussed in the preliminary design of GRIFINOR. The system involves use of several different methods for semi-automatic generation of 3D objects from LIDAR data, Orthophotos, building footprints and data from various public registers. At the moment the system is only prepared for generation of static physical elements such as buildings, but later the system will be able to visualize traditional geoinformation such as socio-economic attribute values on “top” of the Virtual Environment. The buildings are generated as objects based on representation in the 2D technical/topographical map, the LIDAR data and information about each building from the national building and dwelling registry (BBR). After each entity is generated as an object it is saved in a custom built object database. This database is the heart of the system and several specific issues regarding the development of it will be discussed. At the front end, a 3D viewer based on a Java-driven scene graph is the core of the graphical user interface. The considerations behind a representational model for the objects will also be presented and finally some discussions about potential viewing platforms.

The Democratizing Potential of Geographic Exploration Systems (GES) Through the Example of GRIFINOR

In this paper we have looked at the obvious possibility that GES can change the very fundament of spatial data infrastructures when it comes to democratization of geo-information. From the ideas of “Digital Earth” to the situation of today where several vendors has launched equivalent solutions to support the idea of GES. The second part of the paper presented a new GES called GRIFINOR, where major principles such as distributable network, object-orientation and open source was explained. With the launch of GRIFINOR, a new and exiting platform for geographic exploration is accessible for everyone. Next step in this evolution will be development of specific applications that can run on the platform. We hope this will take place in the near future.

Chapter 19 – Modelling Virtual Environments for Geovisualization: A Focus on Representation

The use of virtual environments in geovisualization has become a major topic within the last few years. The main reason for this interest is the growing use of 3D models and visual realizations of these representations in a wide range of applications concerned with the geographic element of information. The implementation and use of virtual environments has developed from being a rather sophisticated type of visualization that demanded extreme computer resources to become an integral part of the software on every desktop computer. This chapter addresses both philosophical and technical issues regarding the modelling of virtual environments. It specifically focuses on the different representational aspects to be taken into consideration when a virtual environment is created. These aspects are data modelling, 3D modelling and level-of-detail. A range of different approaches can be taken to visualize a virtual environment within the geographic domain. A categorization of the virtual environments is offered through which the differences between them are highlighted. It is possible to achieve this categorization in many ways and from many perspectives since this is not and will not be research of a purely positivistic nature. The two variables used for the categorization in this chapter are level of abstraction and the temporal characteristic of the model.