Peter van Oosterom

The core cadastral domain model

Abstract A standardized core cadastral domain model (CCDM), covering land registration and cadastre in a broad sense (multipurpose cadastre), will serve at least two important goals: (1) Avoid re-inventing and re-implementing the same functionality over and over again, but provide a extensible basis for efficient and effective cadastral system development based on a model driven architecture (MDA), and (2) enable involved parties, both within one country and between different countries, to communicate based on the shared ontology implied by the model. The second goal is very important for creating standardized information services in an international context, where land administration domain semantics have to be shared between countries (in order to enable needed translations). This paper presents an overview of the core cadastral domain model and its developments over the last 4 years. The model has been developed in a set of versions, which were each time adjusted based on the discussions at workshops with international experts and the experience from case studies in several countries of the world (Netherlands, El Salvador, Bolivia, Denmark, Sweden, Portugal, Greece, Australia, Nepal, Egypt, Iceland, and several African and Arab countries). Important conditions during the design of the model were and still are: should cover the common aspects of cadastral registrations all over the world, should be based on the conceptual framework of Cadastre 2014, should follow the international ISO and OGC standards, and at the same time the model should be as simple as possible in order to be useful in practise. Besides presenting the CCDM itself this paper represents an important new wave in geo-information standardization: after the domain independent basic geo-information standards (current series of ISO and OGC standards), the new standards based on specific domains will now be developed. Due to historical differences between countries (and regions) similar domains, such as the cadastral domain, may be modeled differently and therefore non-trivial harmonisation has to be done first. The presented CCDM is a result of this harmonisation and one of the first presented examples of semantic geo-information domain standards. Besides the three well-known concepts, Parcel, Person and Right, at the class level the model also includes immovables such as Building and OtherRegisterObject (geometry of easement, like a right of way, protected region, legal space around utility object, etc.) and the following concepts: SourceDocument such as SurveyDocument or LegalDocument (e.g. deed or title), Responsibilities, Restrictions (defined as Rights by other Person than the one having the ownership Right) and Mortgages. At the attribute level of the model the following aspects are included: SalePrize, UseCode, TaxAmount, Interest, Ranking, Share, Measurements, QualityLabel, LegalSize, EstimatedSize, ComputedSize, TransformationParams, PointCode, and several different date/times. The heart of the model is based on the three classes: (1) RegisterObject (including all kinds of immovables and movables), (2) RRR (right, restriction, responsibility), and (3) Person (natural, non-natural and group). The model supports the temporal aspects of the involved classes and offers several levels of Parcel fuzziness: Parcel (full topology), SpaghettiParcel (only geometry), PointParcel (single point), and TextParcel (no coordinate, just a description). The geometry and topology (2D and 3D) are based on the OGC and ISO/TC211 standard classes. The model is specified in UML class diagrams and it is indicated how this UML model can be converted into and XML schema, which can then be used for actual data exchange in our networked society (interoperability).

Modelling 3D spatial objects in a geo-DBMS using a 3D primitive

The objective of this thesis is answering the following question: How can 3D spatial objects be modelled (i.e. /stored, validated, queried) in a Geo-DBMS using 3D primitives and how can these objects be visualised? To answer this question the theory from various literature is used to create a prototype implementation of a 3D primitive in a Geo-DBMS. 3D Spatial objects are stored with the polyhedron as (3D) primitive. This primitive is easy for users to model objects, can fairly easily be validated, because the algorithms are not too difficult to implement and still result in realistic objects. Each polyhedron has a set of faces, which consist of a set of ordered nodes. These nodes point to a vertex (x,y,x). This means that the data model is geometric with internal topology. Th epolyhedron is stored within the original Oracle Spatial geometry data model. The validation occurs by checking if the polyhedra are stored correctly and after that checking each characteristic of the polyhedra. These characteristics are: flat faces, should bound one volume, simplicit faces and orientable. The improve the performance of queries, a spatial index should be made on a table with polyhedra. The standard Oracle Spatial indices can be used, because of the way the polyhedra are stored in the Oracle Spatial geometry model. A bounding box is constructed around the 3D line or its projection in case of a 2D spatial index. A test shows that it is preferable to create a 3D spatial index (3D R-tree) rather than a 2D spatial index, to get maximal query performance. Using functions that are part of Oracle Spatial, is not suitable for 3D objects, because these functions work with the 2D projection of the 3D objects. Instead, some of the most commonly used functions (e.g. area, volume, point-in-polyhedron and bounding box) are implemented in 3D, so that functions return a realistic value. The polyhedra can be visualised in GIS and CAD programs that can make a DBMS connection. To do this, the polyhedra have to be exported to 3D multi-polygons. This export function is implemented, as is the import function that makes a polyhedron from a 3D multi-polygon. To visualise polyhdra in a VRML viewer, the objects in the database can be exported to a VRML file. This function is implemented, as is the function to make a polyhedron from a VRML object. These concousions together satify the goal to implement a 3D primitive in a Geo-DBMS in a way that improves the maintainability of 3D spatial data and opens the door to more realistic applications.

Ontology-Based Geographic Data Set Integration

In order to develop a system to propagate updates we investigate the semantic and spatial relationships between independently produced geographic data sets of the same region (data set integration). The goal of this system is to reduce operator intervention in update operations between corresponding (semantically similar) geographic object instances. Crucial for this reduction is certainty about the semantic similarity of different object representations. In this paper we explore a framework for ontology-based geographic data set integration, an ontology being a collection of shared concepts. Components of this formal approach are an ontology for topographic mapping (a domain ontology), an ontology for every geographic data set involved (the application ontologies), and abstraction rules (or capture criteria). Abstraction rules define at the class level the relationships between domain ontology and application ontology. Using these relationships, it is possible to locate semantic similarity at the object instance level with methods from computational geometry (like overlay operations). The components of the framework are formalized in the Prolog language, illustrated with a fictitious example, and tested on a practical example.

Variable-scale Topological Data Structures Suitable for Progressive Data Transfer: The GAP- face Tree and GAP-edge Forest

This paper presents the first data structure for a variable scale representation of an area partitioning without redundancy of geometry. At the highest level of detail, the areas are represented using a topological structure based on faces and edges; there is no redundancy of geometry in this structure as the shared boundaries (edges) between neighbor areas are stored only once. Each edge is represented by a Binary Line Generalization (BLG)-tree, which enables selection of the proper repre- sentation for a given scale. Further, there is also no geometry redundancy between the different levels of detail. An edge at a higher importance level (less detail) does not contain copies of the lower-level edges or coordinates (more detail), but it is represented by efficiently combining their corresponding BLG trees. Which edges have to be combined follows from the generalization computation, and this is stored in a data structure. This data structure turns out to be a set of trees, which will be called the (Generalized Area Partitioning) GAP-edge forest. With regard to faces, the generalization result can be captured in a single tree structure for the parent-child relationships—the GAP face-tree. At the client side there are no geometric computations necessary to compute the polygon representations of the faces, merely following the topological references is sufficient. Finally, the presented data structure is also suitable for progressive transfer of vector maps, assuming that the client maintains a local copy of the GAP-face tree and the GAP-edge forest.This paper presents the first data structure for a variable scale representation of an area partitioning without redundancy of geometry. At the highest level of detail, the areas are represented using a topological structure based on faces and edges; there is no redundancy of geometry in this structure as the shared boundaries (edges) between neighbor areas are stored only once. Each edge is represented by a Binary Line Generalization (BLG)-tree, which enables selection of the proper representation for a given scale. Further, there is also no geometry redundancy between the different levels of detail. An edge at a higher importance level (less detail) does not contain copies of the lower-level edges or coordinates (more detail), but it is represented by efficiently combining their corresponding BLG trees. Which edges have to be combined follows from the generalization computation, and this is stored in a data structure. This data structure turns out to be a set of trees, which will be called the (Generalized Area Partitioning) GAP-edge forest. With regard to faces, the generalization result can be captured in a single tree structure for the parent-child relationships—the GAP face-tree. At the client side there are no geometric computations necessary to compute the polygon representations of the faces, merely following the topological references is sufficient. Finally, the presented data structure is also suitable for progressive transfer of vector maps, assuming that the client maintains a local copy of the GAP-face tree and the GAP-edge forest.

5D data modelling: full integration of 2D/3D space, time and scale dimensions

This paper proposes an approach for data modelling in five dimensions. Apart from three dimensions for geometrical representation and a fourth dimension for time, we identify scale as fifth dimensional characteristic. Considering scale as an extra dimension of geographic information, fully integrated with the other dimensions, is new. Through a formal definition of geographic data in a conceptual 5D continuum, the data can be handled by one integrated approach assuring consistency across scale and time dimensions. Because the approach is new and challenging, we choose to step-wise studying several combinations of the five dimensions, ultimately resulting in the optimal 5D model. We also propose to apply mathematical theories on multidimensional modelling to well established principles of multidimensional modelling in the geo-information domain. The result is a conceptual full partition of the 3Dspace+time+scale space (i.e. no overlaps, no gaps) realised in a 5D data model implemented in a Database Management System.

Transportation mode-based segmentation and classification of movement trajectories

The knowledge of the transportation mode used by humans (e.g. bicycle, on foot, car and train) is critical for travel behaviour research, transport planning and traffic management. Nowadays, new technologies such as the Global Positioning System have replaced traditional survey methods (paper diaries, telephone) because they are more accurate and problems such as under reporting are avoided. However, although the movement data collected (timestamped positions in digital form) have generally high accuracy, they do not contain the transportation mode. We present in this article a new method for segmenting movement data into single-mode segments and for classifying them according to the transportation mode used. Our fully automatic method differs from previous attempts for five reasons: (1) it relies on fuzzy concepts found in expert systems, that is membership functions and certainty factors; (2) it uses OpenStreetMap data to help the segmentation and classification process; (3) we can distinguish between 10 transportation modes (including between tram, bus and car) and propose a hierarchy; (4) it handles data with signal shortages and noise, and other real-life situations; (5) in our implementation, there is a separation between the reasoning and the knowledge, so that users can easily modify the parameters used and add new transportation modes. We have implemented the method and tested it with a 17-million point data set collected in the Netherlands and elsewhere in Europe. The accuracy of the classification with the developed prototype, determined with the comparison of the classified results with the reference data derived from manual classification, is 91.6%.

Data model for the collaboration between land administration systems and agricultural land parcel identification systems.

The Common Agricultural Policy (CAP) of the European Union (EU) has dramatically changed after 1992, and from then on the CAP focused on the management of direct income subsidies instead of production-based subsidies. For this focus, Member States (MS) are expected to establish Integrated Administration and Control System (IACS), including a Land Parcel Identification System (LPIS) as the spatial part of IACS. Different MS have chosen different solutions for their LPIS. Currently, some MS based their IACS/LPIS on data from their Land Administration Systems (LAS), and many others use purpose built special systems for their IACS/LPIS. The issue with these different IACS/LPIS is that they do not have standardized structures; rather, each represents a unique design in each MS, both in the case of LAS based or special systems. In this study, we aim at designing a core data model for those IACS/LPIS based on LAS. For this purpose, we make use of the ongoing standardization initiatives for LAS (Land Administration Domain Model: LADM) and IACS/LPIS (LPIS Core Model: LCM). The data model we propose in this study implies the collaboration between LADM and LCM and includes some extensions. Some basic issues with the collaboration model are discussed within this study: registration of farmers, land use rights and farming limitations, geometry/topology, temporal data management etc. For further explanation of the model structure, sample instance level diagrams illustrating some typical situations are also included.

Advances in 3D Geoinformation Systems

This unique book focuses on comparing several types of 3D models. Due to the rapid developments in sensor techniques a vast amount of 3D data is available. Effective algorithms for (semi) automatic object reconstruction are required. Integration of existing 2D objects with height data is a non-trivial process and needs further research. The resulting 3D models can be maintained in several types of 3D models: TEN (Tetrahedral Network), Constructive Solid Geometry (CSG) models, Regular Polytopes, TIN Boundary representation and 3D volume quad edge structure, layered/topology models, voxel based models, 3D models used in urban planning/polyhedrons, and n-dimensional models including time. 3D analysis and 3D simulation techniques explore and extend the possibilities in spatial applications.

On Valid and Invalid Three-Dimensional Geometries

Advances in storage management and visualization tools have expanded the frontiers of traditional 2D domains like GIS to 3Dimensions. Recent proposals such as CityGML and associated gateways bridge a long-standing gap between the terrestrial models from the GIS and the CAD/CAM worlds and shift the focus from 2D to 3D. As a result, efficient and scalable techniques for storage, validation and query of 3D models will become a key to terrestrial data management. In this paper, we focus on the problem of validation of 3D geometries. First we present Oracle’s data model for storing 3D geometries (following the general OGC/ISO GML3 specifications). Then, we define more specific and refined rules for valid geometries in this model. We show that the solid representation is simpler and easier to validate than the GML model but still retains the representative power. Finally, we present explicit examples of valid and invalid geometries. This work should make it to easy to conceptualize valid and invalid 3D geometries.

Enhancing Geo‐Service Chaining through Deep Service Descriptions

We demonstrate the integrated use of semantic and syntactic service descriptions, called deep service descriptions, for service chaining by combining two prototypes: one that deals with geoservice discovery abstract composition (called ‘GeoMatchMaker’), with one that supports concrete composition and execution of geoservices services (called ‘Integrated Component Designer’). Most other service chaining approaches confine themselves to handling either syntactic or semantic service descriptions. The proprietary formats of these descriptions hamper an effective integration of discovery, composition and execution of multiple services. In essence, service chaining should help a user by