Constrained tGAP for generalisation between scales: the case of Dutch topographic data

This article presents the results of integrating large- and medium-scale data into a unified data structure. This structure can be used as a single non-redundant representation for the input data, which can be queried at any arbitrary scale between the source scales. The solution is based on the constrained topological Generalized Area Partition (tGAP), which stores the results of a generalization process applied to the large-scale dataset, and is controlled by the objects of the medium-scale dataset, which act as constraints on the large-scale objects. The result contains the accurate geometry of the large-scale objects enriched with the generalization knowledge of the medium-scale data, stored as references in the constraint tGAP structure. The advantage of this constrained approach over the original tGAP is the higher quality of the aggregated maps. The idea was implemented with real topographic datasets from The Netherlands for the large- (1:1000) and medium-scale (1:10,000) data. The approach is expected to be equally valid for any categorical map and for other scales as well

Constrained set-up of the tGAP structure for progressive vector data transfer

A promising approach to submit a vector map from a server to a mobile client is to send a coarse representation first, which then is incrementally refined. We consider the problem of defining a sequence of such increments for areas of different land-cover classes in a planar partition. In order to submit well-generalised datasets, we propose a method of two stages: First, we create a generalised representation from a detailed dataset, using an optimisation approach that satisfies certain cartographic constraints. Second, we define a sequence of basic merge and simplification operations that transforms the most detailed dataset gradually into the generalised dataset. The obtained sequence of gradual transformations is stored without geometrical redundancy in a structure that builds up on the previously developed tGAP (topological Generalised Area Partitioning) structure. This structure and the algorithm for intermediate levels of detail (LoD) have been implemented in an object-relational database and tested for land-cover data from the official German topographic dataset ATKIS at scale 1:50 000 to the target scale 1:250 000. Results of these tests allow us to conclude that the data at lowest LoD and at intermediate LoDs is well generalised. Applying specialised heuristics the applied optimisation method copes with large datasets; the tGAP structure allows users to efficiently query and retrieve a dataset at a specified LoD. Data are sent progressively from the server to the client: First a coarse representation is sent, which is refined until the requested LoD is reached

06101 Abstracts Collection -- Spatial Data:mining, processing and communicating

From 05.03.06 to 10.03.06, the Dagstuhl Seminar 06101 ``Spatial Data: mining, processing and communicating\u27\u27 was held in the International Conference and Research Center (IBFI), Schloss Dagstuhl. During the seminar, several participants presented their current research, and ongoing work and open problems were discussed. Abstracts of the presentations given during the seminar as well as abstracts of seminar results and ideas are put together in this paper. The first section describes the seminar topics and goals in general. Links to extended abstracts or full papers are provided, if available

SPLITAREA: an algorithm for weighted splitting of faces in the context of a planar partition

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Groundwater management in land administration: a spatio-temporal perspective

Although the use of land and water is intertwined, specifics for groundwater management are not effectively dealt with in the laws and other institutional mechanisms related to land. Provisions for groundwater aspects in land management are there, but with a focus on the land itself. Land rights and restrictions are more or less static, lacking enough flexibility to incorporate the relatively short interval spatio-temporal dynamics of groundwater resources in the land management and regulation mechanisms. This leads to a gap between the scientific inputs and policy-decision making. The paper suggests the adaptation of a spatial information science based approach to bridge the gap between the technical and administrative aspects of groundwater management. The land administration domain model (LADM) provides a basic set of elements capable of supporting the inclusion of basic groundwater modeling elements into land administration, making it possible to create a support system for the management of land and water. For this purpose, spatial and temporal dimensions under the legal-administrative and spatial unit components of the standard LADM model are reviewed. The paper shows that the advancement of spatial technologies is capable of providing solutions for global issues such as groundwater resource management. As a first step towards implementation of these technologies, it is essential to include spatio-temporal dynamics properly in the standard data models. Increased knowledge of the behaviour of groundwater resources, supported by a technical system built on a land administration counterpart, could help improve greater sustainability in the use of such resources. Considering the specific arrangements of rights, parties and spatial units this could, if desired, also provide the base for a regulated private market in groundwater assets. Further research will be needed to fully operationalize and implement such data models, which ultimately could produce outputs at case study level which can help to formulate policies regarding natural resources more on the basis of technical inputs

Spatial dimensions of land administration and user rights over groundwater: case study of Kerala, India vs. Coca Cola

Supporting the management of rights related to groundwater based on input from hydrogeology software is contributing to bridging the gap between the technical and administrative aspects of groundwater management. The research reported herein is focused on a specific example (or ‘use case’ in UML terminology), resulting from a court action by Kerala State in India, against the Coca-Cola company, on the overexploitation of the local groundwater aquifer. The use case reports on the economic and policy contexts conducing to the establishment of the Coca-Cola bottling plant in Plachimada, and the ensuing court actions, triggered by the local community assembly first, and then by Kerala State authority, on the grounds of the introduction of toxic waste into the groundwater, making the water unfit for human consumption, and the depletion of the aquifer. Considering the specifics of the use case, the ISO/TC211 Land Administration Domain Model (LADM, DIS 19152) is used as a basis for the development of a specialized profile addressing the need to define laws and regulations with proper spatial and temporal dimensions, to represent the rights to groundwater use by the local communities. Two alternative scenarios are reported: the first is based in the consideration that all the different Property parcels are regulated by Private Law; the second, further develops on the consideration of groundwater as a Public Trust, thus regulating private use through the Public Law domain. The modelling here provided goes from a subset of the LADM conceptual classes to more specialized classes, and is reported through the use of class and instance level (object) diagrams. These build on the existing spatial unit package and the legal and administrative profile, demonstrating the flexibility which can be introduced by LADM. Specifically concerning the representation of spatial units, a previously proposed ‘Mixed 2D/3D’ spatial profile is further developed, addressing the needs of the use case. In combination with the ‘Level’ representation of LADM to organize spatial units, it can contribute to an easier reuse of existing, 2D based, land parcels data, into the proposed 3D and time based model architecture. Concluding, the modelling and architectural framework here reported contributes to a more informed decision in the choice of groundwater rights to be made by the law, policy and courts, taking into account societal needs and changes induced by new socio-economic contexts. The resulting institutional setting will be best informed with spatial and temporal data, and the legal solution chosen be it public or private law focused, can be recorded in a system based on the LADM standard; it allows for much flexibility and only a few specific classes need to be added and further specified in order to be implemented

3D cadastral complexities in dense urban areas of developing countries: case studies from Delhi and satellite towns

Cadastral systems based on 2D spatial representation have served land administration and property management well for centuries. In India, the basic unit of the cadastral record is the land parcel, which is known as plot. Maintenance of land records with ownership; assessment of tax on the property and tax collection is the responsibility of district authorities. Historically, Delhi has been preferred as a capital by different rulers from various dynasties and invaders coming from different partTS03B_ezeomedo_igbokwe_6421s of the world even before 15th century. As in many densely populated areas even the early developments included 3D solutions, both below and above the surface. In the early days these were rather exceptions, but the 3D use of space has only been increased afterwards due to the continuously growing needs for space and the increased (civil) engineering and construction capabilities. In the early decades after gaining independence in 1947, Delhi rapidly began taking shape of a metro city due to large number of refugees coming from Pakistan who changed the landscape of entire Delhi. By the starting of 21st Century, Delhi had started growing rapidly in terms of population and infrastructure development. This rapid expansion in Delhi and immediate neighbouring cities of Noida and Gurgaon found the land administration agencies of these cities unprepared to deal with this rapidly changing land market. Delhi is managed by various land management agencies. Some have a major role to play in planning and development of the land like Delhi Development Authority while others focus more execution and maintenance like municipal corporations. Delhi does have a long-standing system of Deed registration but have no central registry. In general, records of land held by governmental agencies are maintained by each individual agency. The current paper aims to study the multi-stakeholding urban area locations in Delhi and around where (infrastructural) changes are creating the complex land management situations for the authorities involved. Three cases, mainly related to buildings and apartments, are presented in brief to highlight the different aspects of 3D spatial complexities involved while the forth case study is mode elaborated and focusing on multi-infrastructure (utility) networks in one single area. General Spatial Dimensions for each case are discussed focusing on geometric aspects in vertical and horizontal space below or above surface. As a specific focus, the spatial dimensions are discussed within the context of Land Administration Domain Model (LADM) Spatial Unit Package context