Gerhard Navratil

Processes in a cadastre

Abstract A cadastre is a system of major importance for economy and planning. A cadastre provides data on land. It is the basis for legal aspects like ownership as well as fiscal aspects like taxation of land. The cadastre also provides data for planning assignments (for example, boundaries of constructions, land use, and soil). Storage and update of these data require a complex system that had been developed in Austria during more than 100 years. Understanding, using, and improving a cadastre requires knowledge on the cadastral processes. The problems a cadastre must solve are important to understand the needs for a cadastre. It is also important to understand the processes of a cadastre to see how a cadastre works. These processes define the way a cadastre handles data and what prerequisites the data must fulfil to be accepted by the cadastre. Improving a system requires analysis of the processes. The user wants to work with a cadastre. He needs processes that meet his demands. Improving the efficiency of the processes, therefore, improves the efficiency of the cadastre directly because then the user will be satisfied (his work will be done better or faster). The paper discusses the tasks of a cadastre. The starting point is the needs of users (owners, government and many others). The needs define the tasks and the data needed to fulfil the tasks. The next step is the definition of the processes to fulfil the tasks. The paper then formalizes these processes. Finally, implementations for two different cadastral systems prove the general validity of the processes.

Research trends in geographic information science

Section I: Philosophical background and Semantics.- Ontology, Epistemology, Teleology: Triangulating Geographic Information Science.- Geonoemata Elicited: Concepts, Objects, and Other Uncertain Geographic Things.- Virtue Ethics for GIS Professionals.- Why Is Scale an Effective Descriptor for Data Quality? The Physical and Ontological Rationale for Imprecision and Level of Detail.- Semantic Engineering.- Section II: Mathematical Methods.- A Common Spatial Model for GIS.- Computation with Imprecise Probabilities.- Spatial Data Quality: Problems and Prospects.- Latent Analysis as a Potential Method for Integrating Spatial Data Concepts.- Stereology for Multitemporal Images with an Application to Flooding.- Modeling Spatiotemporal Paths for Single Moving Objects.- Moving Objects in Databases and GIS: State-of-the-Art and Open Problems.- The Degree Distribution of Random Planar Graphs.- Section III: Tools and Applications.- Geographical Information Engineering in the 21 Century.- Towards Visual Summaries of Geographic Databases Based on Chorems.- Intelligent Spatial Communication.- Training Games and GIS.- Cadastre and Economic Development.

Requirements of 3D cadastres for height systems

Abstract Three-dimensional (3D) cadastral systems can only be built if there are suitable height reference systems. However, the earth is neither homogeneous nor flat, and the plumb lines are curved and not parallel. Thus, the definition of height and the implementation of geodetic height systems are complex. 3D cadastres must connect to the existing national height reference. In addition, cadastral systems are designed to persist for centuries. Over such long periods, the earth changes, from plate tectonics, erosion, human intervention, etc. Changes in the technology of measurement equipment can also occur, allowing different definitions. These considerations are important in the design of a 3D cadastre. At minimum, the height system used for the cadastre must be well-defined, to enable adjustments from potential changes in the height system or even the actual point heights. This study examines existing height systems and the determination of height in the context of cadastral tasks. Accuracy requirements for height in a 3D cadastre are analyzed using typical examples. The selected height system must support these requirements. This study also develops the questions that must be answered and highlights the problems that can emerge in some of the solutions. There is no height reference system that fits all needs, and each solution has advantages and disadvantages. Different systems may be optimal for different countries. It may also be beneficial to allow different geometrical qualities for different parts of a country.

Spatial Urban Expansion and Land Tenure Security in Ethiopia: Case Studies from Bahir Dar and Debre Markos Peri-Urban Areas

This study analyzes urban expansion and the peri-urban land tenure security situation in Amhara National Regional State of Ethiopia, taking Bahir Dar and Debre Markos as case studies. To detect the extent of urban expansion, data from Landsat satellite images were analyzed using ERDAS IMAGINE, ENVI, and ArcGIS segmentation, classification, and mapping tools. The land tenure security situation was assessed through interviews with local farmers. Analysis shows high rates of spatial urban expansion, but stagnating levels of property registration and certification among peri-urban landholders, affecting their feelings of land tenure security. Though Ethiopias efforts to impart land tenure security by implementing low-cost land registration programs in rural areas are promising, the programs in peri-urban areas are underdeveloped, and these areas are subject to expropriation due to urban expansion. Policies for more sensitive growth are needed in rapidly developing places like these.

Reprint of: Requirements of 3D cadastres for height systems ☆

Abstract Three-dimensional (3D) cadastral systems can only be built if there are suitable height reference systems. However, the earth is neither homogeneous nor flat, and the plumb lines are curved and not parallel. Thus, the definition of height and the implementation of geodetic height systems are complex. 3D cadastres must connect to the existing national height reference. In addition, cadastral systems are designed to persist for centuries. Over such long periods, the earth changes, from plate tectonics, erosion, human intervention, etc. Changes in the technology of measurement equipment can also occur, allowing different definitions. These considerations are important in the design of a 3D cadastre. At minimum, the height system used for the cadastre must be well-defined, to enable adjustments from potential changes in the height system or even the actual point heights. This study examines existing height systems and the determination of height in the context of cadastral tasks. Accuracy requirements for height in a 3D cadastre are analyzed using typical examples. The selected height system must support these requirements. This study also develops the questions that must be answered and highlights the problems that can emerge in some of the solutions. There is no height reference system that fits all needs, and each solution has advantages and disadvantages. Different systems may be optimal for different countries. It may also be beneficial to allow different geometrical qualities for different parts of a country.

Using Weather Information to Improve Route Planning

Weather has a significant influence on navigation processes. Driving during a heavy rain, for example, is slower and due to poor visibility more dangerous than driving in perfect weather conditions. Thus from time management and safety perspective including weather information is beneficial. Weather, especially rain may also be critical for transportation tasks since some commodities like straw or sand should not get wet. In the last years, the quality of weather information and weather forecast has improved and could be used to improve route planning.The paper discusses how weather information can be included in route planning algorithms. A first approximating algorithm to incorporate weather forecast data is presented. Some examples showing the impact on route planning conclude the paper.

Lifting Imprecise Values

The article presents a conceptual framework for computations with imprecise values. Typically, the treatment of imprecise values differs from the treatment of precise values. While precise computations use a single number to characterize a value, computations with imprecise values must deal with several numbers for each value. This results in significant changes in the program code because values are represented, e.g., by expectation and standard deviation and both values must be considered within the computations. It would be desirable to have a solution where only limited changes in very specific places of the code are necessary. The mathematical concept of lifting may lead to such a solution.

What makes Location-Based Services fail?

A lot of research projects deal with location-based services and also telephone providers services. Some services fail to become an economic success. In this paper we investigate possible pitfalls for location-based services. The categories of pitfalls are technical possibilities, legal restrictions, and usability. Using two example services we show how to determine the possible pitfalls.

Maintainable city models for sustainable development

3D city models are getting more important as a field of research and business and received an increasing amount of attention from both the scientific community and the professional field. 3D city models are one of the new tools for sustainable city development. Since development questions occur repeatedly, the used city models should be maintainable, i.e. the system should be kept up-to-date and not be created new for each decision. This is a challenge. Creating a model representing the current status of a city has been addressed in research literature. The major challenge is the vast amount of data to be collected, processed and visualised. However, keeping the resulting model up-to-date has not been discussed yet. Updating requires the introduction of a suitable concept of time in the model. This would then allow representing historic and current status of the city as well as future scenarios. Processes provide the connection between different points in time. Processes also change the appearance of the city and need to be represented in the model for change detection. In this paper, we discuss the challenges and show necessary properties for city models and systems maintaining them to reach a reasonable level of maintainability.

On Reproducing Linear Estimators within the Gauss―Markov Model with Stochastic Constraints

In a Gauss–Markov Model (GMM) with fixed constraints, all the relevant estimators perfectly satisfy these constraints. As soon as they become stochastic, most estimators are allowed to satisfy them only approximately, thereby leaving room for nonvanishing residuals to describe the deviation from the prior information. Sometimes, however, linear estimators may be preferred that are able to perfectly reproduce the prior information in form of stochastic constraints, including their variances and covariances. As typical example may be considered the case where a geodetic network ought to be densified without changing the higher-order point coordinates that are usually introduced together with their variances and (some) covariances. Traditional estimators are based on the “Helmert” or “S-transformation,” respectively an adaptation of the fixed-constraints Least-Squares estimator. Here we show that neither approach generates the optimal reproducing estimator, which will be presented in detail and compared with the other reproducing estimators in terms of their MSE-risks.