P.J.M. van Oosterom

The Balance Between Geometry and Topology

The architecture of Geographic Information Systems (GISs) is changing: more and more systems are based on the integrated architecture, i.e. storing geometric data in the Data Base Management System (DBMS) together with administrative data. The first step in building a Geo-DBMS is by having data types and operators for simple features (i.e. geometric primitives): point, line and polygon. This has reached a level of standardisation and is now implemented in several commercial DBMSs. The next step is to have support for the topologically structured features in the DBMS, i.e. complex features. The DBMS can then check and guarantee consistency. In addition, complex operations can be executed within the DBMS. Despite the fact that topologically structured models are well known and that it is not difficult to store the topological references, it still remains an unresolved issue as to how to effectively implement these models within a relational DBMS. In this paper, we describe the design and implementation of a topologically structured management at the DBMS level. Our focus is to translate topological structures into geometric primitives. It is then possible to define a DBMS view on a topological primitive, which makes this appear as a geometric primitive. This process supports the best of both worlds: on the one hand there are advantages of the topological structure (no redundancy) and on the other hand the ease of explicit geometric primitives in querying, analysis and presentation is available.

Integrating Semantic and Syntactic Descriptions to Chain Geographic Services

Integrating multiple geographic services from different information communities and spatiolinguistic regions is challenging because of its inherent complexity and heterogeneity. A geographic information systems workflow approach can use semantic and syntactic service descriptions to form service chains that can integrate service discovery, composition, and reuse. Service chaining links remote geographic services to help expert users form complex geoprocessing services and perform timely analysis of geodata. This method facilitates the use of XML-based service description languages to build a geoservice-reuse architecture based on common ontologies and shared service descriptions

Spatial data management on a very large cadastral database

Abstract An overview is presented of spatial data management in the Netherlands Cadastre. As a result of more than three years research a major improvement in the accessibility and maintenance of 50 Gb available geometric data has been introduced. Quality assurance of topological relationships, maintenance of historic spatial data and flexible data access by a query tool is supported. The ‘Spatial Location Code’ used for spatial clustering and spatial indexing guarantees excellent performance of the relational database. This opens the possibility to develop new products, which can be delivered efficiently via networks.

Technological aspects of a full 3D cadastral registration

In this paper, we present a new conceptual model for a full 3D cadastral registration system. Two important components are: (1) the ‘surface parcel partition’ based on a detailed elevation model and (2) the volume parcel and its representation. Technological solutions for both parts are not yet available in commercial Geo‐ICT software, and therefore solutions have been investigated, designed and developed (in a Geo‐DBMS environment). A number of countries in the world do already have legislation allowing the registration of volume parcels, sometimes even including detailed regulations for 3D survey plans. However, until now, these have not yet been integrated in the cadastral information system. A 3D case from Queensland, Australia is presented, and a prototype is realized based on an integrated 3D cadastral information system: elevation‐model‐based surface parcels complemented with volume parcels.

A simplicial complex-based DBMS approach to 3D topographic data modelling

This paper introduces a new compact topological 3D data structure. The proposed method models the real world as a complete decomposition of space and this subdivision is represented by a constrained tetrahedral network (TEN). Operators and definitions from the mathematical field of simplicial homology are used to define and handle this TEN structure. Only tetrahedrons need to be stored explicitly in a (single column) database table, while all simplexes of lower dimensions, constraints and topological relationships can be derived in views. As a result the data structure is relatively compact and easy to update, while it still offers favourable characteristics from a computational point of view as well as presence of topological relationships.

3D-GEM: Geo-technical extension towards an integrated 3D information model for infrastructural development

In infrastructural projects, communication as well as information exchange and (re-)use in and between involved parties is difficult. Mainly this is caused by a lack of information harmonisation. Various specialists are working together on the development of an infrastructural project and all use their own specific software and definitions for various information types. In addition, the lack of and/or differences in the use and definition of thematic semantic information regarding the various information types adds to the problem. Realistic 3D models describing and integrating parts of the earth already exist, but are generally neglecting the subsurface, and especially the aspects of geology and geo-technology. This paper summarises the research towards the extension of an existing integrated semantic information model to include surface as well as subsurface objects and in particular, subsurface geological and geotechnical objects. The major contributions of this research are the definition of geotechnical objects and the mechanism to link them with CityGML, GeoSciML and O&M standard models. The model is called 3D-GEM, short for 3D Geotechnical Extension Model. Innovative model (3D-DEM) for semantic and geometric properties of geo-technical data.First model to reflect needs of users involved in infrastructural projects.The model can be easily integrated with above surface data via CityGML.The models provide links to other geological models GeoSciML and O&M.

The land administration domain model (LADM) as the reference model for the Cyprus land information system (CLIS)

In this paper, the enhancement of the data model of the Cyprus land information system (CLIS), with the adoption of the land administration domain model (LADM) is examined. The CLIS was established in 1999, within the Department of Lands and Surveys, to support the operation of the Cyprus cadastral system and has met the majority of its initial set goals. It is however now broadly accepted that the CLIS should be improved and upgraded, and a new data model should be introduced to facilitate the manipulation and provision of data to internal and external users/ customers in a more effective way. The need to enhance the CLIS coincides with the introduction of the LADM, which is under development within the Technical Committee 211 of the International Organization for Standardization and identified as ISO 19152. The LADM provides an abstract, conceptual schema with three basic packages: parties (such as people and organisations), administrative rights, responsibilities and restrictions (such as property rights) and spatial units (such as parcels, buildings and networks), with the latter having one subpackage: surveying and spatial representation [6]. [Note: In this moment (January 2012), the LADM is at the development stage of Final Draft International Standard]. In this paper, the basic entities of the CLIS are presented and restructured, in a way to comply with the LADM. After analysing the characteristics of LADM, it is concluded that this is compatible with CLIS, and can be used as a data model framework for CLIS’s upgrade. Thus, the Cyprus country profile is proposed. The adoption of the LADM is a great opportunity for the Department of Lands and Surveys to introduce an International Organization for Standardization standard model, based on model driven architecture, and to gain all the benefits derived from such a movement. Such benefits include the improvement in the effectiveness and the efficiency of the current system and the expansion of the services provided by CLIS to the broader land administration system and to the Cyprus community. The new functionality includes: better structuring of the rights, responsibilities and restrictions (and related source documents); better fitting in the information infrastructure, both national (e.g. valuation, taxation, building, address and person registrations) and international (e.g. INSPIRE cadastral parcels); and future capabilities for representing three-dimensional spatial units (e.g. legal spaces related to apartment or utility infrastructure).

A Data Model for Multi-scale Topographical Data

The lack of fully automated generalisation forces National Mapping Agencies to maintain topographical data sets at different map scales. For consistency between map scales, but also for supporting (future) automated generalisation processes, information on similarities and differences of the separate data sets should be identified and formalised. This includes information on valid data content at the different scales (‘scale state’), but as important is the semantics of multi-scale and generalisation aspects (‘scale event’). As ‘scale state’ and ‘scale event’ are strongly related (‘different sides of the same coin’) it is important to integrate these in a single model. This paper presents a semantically-rich data model for an integrated topographical database, facilitating (semi-)automated generalisation. UML (including OCL) is used to formalise the model. The scope of the model is outlined and the model is presented based on an analysis of several alternatives for modelling multi-scale and generalisation aspects. The model is evaluated by instantiating the model and applying it to test data.

Developing the information infrastructure based on LADM – the case of Poland

In this paper, the possibilities of developing the national information infrastructure by applying the Land Administration Domain Model (LADM) are discussed. Confirmation of the legitimacy of using the LADM within the (Spatial) Information Infrastructure (SII) context is illustrated with the case of Poland. Creating the information infrastructure is an immense challenge because its components are usually dispersed among various institutions responsible for their maintenance and dissemination. Co-existing spatial and non-spatial components of the information infrastructure require their proper integration. Moreover, the interdisciplinary nature of the SII results in combining objects from physical and legal world in one computer environment. The process of standardisation is the first step to refine land administration system and to make it more understandable and transparent for involved parties. The LADM, being officially adopted as an international standard ISO 19152, gives a basis for building national profiles and supports creating the European information infrastructure, enabling communication based on common terminology. This paper provides a brief overview of the current land information system in Poland emphasising the main issues in creating the national information infrastructure. Then, the general concept of the country profile for Poland with the adaptation of the LADM is described. With respect to the users’ expectations and requirements, the conceptual model is extended to information being outside the scope of LADM. As a final point, several technical aspects of implementing the complemented LADM country profile are explored. The results indicate that effective functioning of the information infrastructure requires proper integration of data, proceeded by analysing the contents of existing data sets, indicating key registers and defining a linkage system between them.

Generalization of integrated terrain elevation and 2D object models

A lot of attention has been paid to generalization (filtering) of Digital Elevation Models (DEMs) and the same is true for generalization of 2D object models (e.g. topographic or land use data). In addition there is a tendency to integrate DEMs with classified real-world objects or features, the result is sometimes called a Digital Terrain Model (DTM). However, there has not been much research on the generalization of these integrated elevation and object models. This paper describes a four step procedure. The first two steps have been implemented and tested with real world data (laser elevation point clouds and cadastral parcels). These tests have yielded promising results as will be shown in this paper.