Andreas Thomsen

Management and visualization of large, complex and time-dependent 3D objects in distributed GIS

This paper presents solutions for architectures of distributed GIS employed for large scale geological modeling in contrast with more traditional GIS. Key technologies are proposed for dealing with complex geological spatio-temporal 3D models. These techniques are then illustrated on a prototype system developed to support interactive work on large models employed by existing geological 3D modeling tools. This prototype has already been successfully applied to the construction of large 3D and 4D models in a geological research project concerning the development of large 3D kinematic models of selected regions within the Lower Rhine Basin. We expect that the enhanced facility in handling large sets of complex data provided by these techniques will enable geoscientists to create more comprehensive and more powerful GIS.

Towards a balanced 3D kinematic model of a faulted domain - the Bergheim open pit mine, Lower Rhine Basin

In the context of the investigation of the sedimentary and structural evolution of the Cenozoic Lower Rhine Basin, the construction of a volume-balanced kinematic model of a small faulted domain with detailed spatial information on strata and fault geometry from a set of parallel geological sections is under development. A 3D geometry model is built that allows for relative movements of blocks at fault surfaces. Rouby’s method of restoration in the map plane is used to determine horizontal displacement fields. The 3D and 3D(t) geometry models are supported by the object-oriented geometry database tool GeoToolKit for storage and retrieval of selected parts of the model using queries referring to spatial and temporal criteria, while visualization is based on key frame technique.

Modelling and Managing Topology in 3D Geoinformation Systems

Modelling and managing topology in 3D GIS is a non-trivial task. The traditional approaches for modelling topological data in 2D GIS cannot be easily extended into higher dimensions. In fact, the topology of real 3D models is much more complex than that of the 2D and 2.5D models used in classical GIS; in consequence there is a great number of different 3D spatial models ranging from constructive solid geometry to boundary representations. The choice of a particular representation is generally driven by the requirements of a given application. Nevertheless, from a data management point of view, it would be useful to provide a general topological model handling 2D, 2.5D and 3D models in a uniform way. In this paper we describe concepts and the realisation of a general approach to modelling and managing topology in a 3D GIS based on oriented d-Generalised Maps and the closely related cell-tuple structures. As an example of the applicability of the approach, the combination of a group of buildings from a 3D city model with the corresponding part of a 2D city is presented. Finally, an outlook to ongoing research is given in the context of topological abstraction for objects represented in multi-representation databases.

DB4GeO, a 3D/4D Geodatabase and Its Application for the Analysis of Landslides

The analysis and preparation of information are still particularly critical points in the early warning chain of natural hazards. Also there is a strong demand for analyzing geological hazards such as earthquakes, landslides, and tsunamis. Therefore the management of heterogeneous and large sets of geodata may become one of the key issues in early warning and emergency management. Geodatabases may support the analysis of landslides significantly, as the responsible decision makers are usually confronted with huge amounts of original and interpreted data. The 3D/4D geodatabase introduced in this chapter provides efficient geodata retrieval by its service-based architecture which enables an easy-to-use internet-based geodata access . Concepts and implementation issues for the management of spatial and spatiotemporal data are presented. An application scenario for early warning demonstrates the applicability of the proposed approach. Finally a conclusion and an outlook on future research are presented within a distributed software environment for early warning geotools.

Topological and Geometric Data Handling for Time-Dependent Geo-Objects Realized in DB4GeO

In advanced spatio-temporal scenarios, such as the simulation of complex geo-processes, the analysis of complex surface- and volume-based objects changing their locations and shapes in time is a central task. For example, the documentation of landfills, mass movements or volcanic activities requires 4D modeling based on dynamic geometric and topological database structures. In this contribution we present our concepts and implementation efforts for the effective handling of geospatial and time-dependent data realized in DB4GeO, a service-based geo-database architecture. The topological and geometric data models of DB4GeO are described in detail. A geoscientific application of an open-pit mine demonstrates the usefulness of the concepts introduced at the beginning of the paper. Finally, an outlook is given on future geo-database work dealing with extensions of DB4GeO and the handling of geo-objects in the context of cooperative 4D metro tracks planning

Some Remarks on Topological Abstraction in Multi Representation Databases

Topology is playing a central role in GIS and data integration. However, the standardisation of topological data models, especially for data represented at different levels of detail, has not yet far progressed. The multi-representation of geo-objects poses new challenges, resulting in the development of Multi-Representation Databases. MRDB manage objects with changing scale and level of detail. As spatial models change their content over time, the users require various representations of geo-objects. A general model based on oriented hierarchical d-Generalized Maps is introduced to represent topology in a MRDB. The model can be used as a data integration platform for 2D, 3D, and 4D topology. The realisation of the approach results in a topological toolbox comprising elementary and complex tools for single and multiple representations. An application example is presented, which uses 2D cartographic datasets from Hannover University. Finally, an outlook to ongoing research is given.

Modeling and Managing Topology for 3-D Track Planning Applications

Topology plays a central role in the modelling and management of n-d geo-information. However, hitherto the standardization of n-d topological data models is still at its beginning. A general model based on oriented hierarchical d-Generalised Maps is proposed to handle topology in object-oriented geo-database management systems. The implementation of the approach is demonstrated as module in DB4GeO, our service-oriented 3-d geo-database architecture. A 3-d tracks planning application example in the city of Munich is presented demonstrating the usage of the n-d topological model. Finally, an outlook on our ongoing 3-d geoinfo research in the Dubai region is given.

Scale Problems in Geometric-Kinematic Modelling of Geological Objects

To reveal, to render and to handle complex geological objects and their history of structural development, appropriate geometric models have to be designed. Geological maps, sections, sketches of strain and stress patterns are such well-known analogous two-dimensional models. Normally, the set of observations and measurements supporting them is small in relation to the complexity of the real objects they derive from. Therefore, modelling needs guidance by additional expert knowledge to bridge empty spaces which are not supported by data. Generating digital models of geological objects has some substantial advantages compared to conventional methods, especially if they are supported by an efficient database management system. Consistent 3D models of some complexity can be created, and experiments with time-dependent geological geometries may help to restore coherent sequences of paleogeological states. In order to cope with the problems arising from the combined usage of 3D-geometry models of different scale and resolution within an information system on subsurface geology, geometrical objects need to be annotated with information on the context, within which the geometry model has been established and within which it is valid, and methods supporting storage and retrieval as well as manipulation of geometry at different scales must also take into account and handle such context information to achieve meaningful results. An example is given of a detailed structural study of an open pit lignite mine in the Lower Rhine Basin.

Temporal and Spatial Database Support for Geothermal Sub-surface Applications

Geothermal energy production from the deep subsurface requires a detailed knowledge of the relevant static and transient parameter distribution in the reservoir and host rock. In reservoir exploration, engineering and operation phases, both temporal and spatial subsurface parameters are acquired, evaluated and monitored in order to improve the reservoir performance. To support temporal and spatial data access to geothermal data sources, an efficient 3D/4D GIS is proposed in this study. We discuss theoretical and first practical approaches for the management of such temporal and spatial geothermal data. A first practical example is provided using the data acquired in the Soultz-sous-Forets geothermal project (France). A distributed software architecture, database design, and the concept for advanced query component with embedded simulations are presented. Finally, we give an outlook on the planned future research in 3D data management of subsurface, near-surface, and above-surface installations in other projects.