The objective of this paper is to discuss methods of producing a digital terrain model (DTM) from different quality datasets. The current quantity of DTMs and other spatial databases offers potential ...for an enhanced production of DTMs with a better quality than is currently obtainable. Two methods of integrating different datasets are described in this paper. The first is based on the simultaneous interpolation of all useful spatial data sources, and is supported by a proper prediction function according to the weights. The second - weighted sum of data with geomorphologic enhancement - sequentially combines individual datasets according to their weights and is maintained by geomorphologic enhancement. The weights in both methods depend on the output of the used spatial datasets quality control. The methods are tested with regard to original methodological solutions of DTM production developed for the integration of datasets.
Abstract
The LiDAR point clouds captured with airborne laser scanning provide considerably more information about the terrain surface than most data sources in the past. This rich information is not ...simply accessed and convertible to a high quality digital elevation model (
DEM
) surface. The aim of the study is to generate a homogeneous and high quality
DEM
with the relevant resolution, as a 2.5
D
surface. The study is focused on extraction of terrain (bare earth) points from a point cloud, using a number of different filtering techniques accessible by selected freeware. The proposed methodology consists of: (1) assessing advantages/disadvantages of different filters across the study area, (2) regionalization of the area according to the most suitable filtering results, (3) data fusion considering differently filtered point clouds and regions, and (4) interpolation with a standard algorithm. The resulting
DEM
is interpolated from a point cloud fused from partial point clouds which were filtered with multiscale curvature classification (
MCC
), hierarchical robust interpolation (
HRI
), and the
LAS
tools filtering. An important advantage of the proposed methodology is that the selected landscape and datasets properties have been more holistically studied, with applied expert knowledge and automated techniques. The resulting highly applicable
DEM
fulfils geometrical (numerical), geomorphological (shape), and semantic quality properties.
An algorithm of automated karst depression recognition uses a digital terrain model (DTM) and mainly applies the methods of a moving window with a kernel size of 3 3 cells using focal functions. It ...is divided into four parts: watershed calculation, depression delineation, higher level depression delineation and elimination of non-karst depressions. The essential part of the algorithm is the delineation of depression by the elevation of the lowest border cell of watershed. Depressions at higher levels are recognised by filling previously recognised depressions. The performance of algorithm was tested on test area in the Kras region (Slovenia) using DTMs with a spatial resolution of 12.5 m and 3 m. The results mainly depend on the DTM characteristics and quality, especially of their spatial resolution.
A spatial ETL tool that allows interoperability between spatial and non-spatial data is presented in this article. The primary goal of the tool is to provide spatial data processing and ...transformation among various data formats. This is made possible by the ETL process, which extracts, transforms and loads data. The use of spatial data has become significant in everyday life, because only correctly applying the data enables users to extract the true value spatial data offers. The main purpose of this article is to demonstrate the capability and usability of the spatial ETL tool, in order to introduce a more detailed definition of the ETL process to acquaint the reader with the FME Desktop tool, and to demonstrate the applicability of the tool in two case studies. In the first case, a unified spatial data warehouse is built from non-homogeneous data warehouses in order to assess the impacts and effects the geological basis had on the amount of damage to buildings in the 2004 earthquake. The second case demonstrates how the spatial ETL tool can be used to inform locals of predicted spatial changes in the area. The flexibility and the efficiency of the spatial ETL tool are successfully demonstrated in both cases; ETL turns out to be a robust tool for editing and analysing data.
Geographic information systems have been applied on the World Wide Web with different approaches and there is a need to recognize how different groups of users conceptualize the domain of geographic ...space. In the authors research, they present an attempt to model a semantic reference system in a semantic web by the concept of global geo-ontology. Taxonomy is based on general knowledge representation as physical and conceptual shapes, simultaneously with basic and advanced human activities. Developed ontology includes 588 concepts on five levels and is extendable. Within such a structure, the rules as independence of location, time frame and culture are respected.
Spatial data sources, like the geodetic reference system, administrative spatial units, addresses and topographic maps, serve as a base for geo-referencing to the most of dependant thematic spatial ...databases. The marketing strategy of the surveying profession towards the users of spatial data infrastructure should be in the design of an integrative semantic reference system to be used within the Semantic Web, or so-called Web 3.0. The main motivation for our research was the representation of possibilities to automate tool development for efficient and more sensible approaches to query information within web-published spatial data. In contemporary research there are several solutions offered as upgrades of basic GIS systems with the knowledge presented in the form of ontologies. Therefore, we are faced with the new generation of GIS technology, which has been named "inteligent GIS". In this article, we present method of modelling the semantic reference system as an application of the ontology of geographic space in the subset of first order predicate calculus. Such a semantic network of geographic space represents the foundation for semantic data analyses and data integration in distributed information systems. Our application is based on the methods of machine learning and use of the Prolog programming language.
Prostorski podatkovni viri, kot so geodetski referenčni sistem, administrativne prostorske enote, naslovi in topografske teme, so v vseh prostorskih podatkovnih zbirkah podlaga za zajem podatkov in ...položajno umeščanje tematskih podatkov v prostoru. Temeljne strategije geodetske stroke za približevanje potrebam uporabnikov geodetskih podatkov v smislu povezovanja zbirk podatkov so v oblikovanju povezovalnega semantičnega referenčnega sistema v semantičnem spletu ali tako imenovanem spletu 3.0. V tem prispevku so prikazane možnosti za razvoj orodja za enostavnejše in bolj smiselno iskanje ter integracijo na spletu objavljenih prostorskih podatkov. Za rešitev težave je v raziskavah mogoče zaslediti predloge o nadgradnji sedanjih GIS kot sistemov z znanjem, predstavljenim v obliki ontologij. Gre torej za novo generacijo tehnologije GIS, ki jo nekateri imenujejo tudi pametni GIS. Za zdaj takšen GIS obstaja predvsem na teoretični, ne pa tudi na praktični ravni. V tem delu je predstavljena metoda za modeliranje ontologije geografskega prostora v podmnožici predikatnega računa prvega reda. Izdelano semantično omrežje prostora omogoča analize obstoječih zbirk podatkov za namene integracije v okolju porazdeljenih informacijskih sistemov. Naša izvedba temelji na metodah strojnega učenja in uporabi programskega jezika prolog ; Spatial data sources, like the geodetic reference system, administrative spatial units, addresses and topographic maps, serve as a base for geo-referencing to the most of dependant thematic spatial databases. The marketing strategy of the surveying profession towards the users of spatial data infrastructure should be in the design of an integrative semantic reference system to be used within the Semantic Web, or so-called Web 3.0. The main motivation for our research was the representation of possibilities to automate tool development for efficient and more sensible approaches to query information within web-published spatial data. In contemporary research there are several solutions offered as upgrades of basic GIS systems with the knowledge presented in the form of ontologies. Therefore, we are faced with the new generation of GIS technology, which has been named "inteligent GIS". In this article, we present method of modelling the semantic reference system as an application of the ontology of geographic space in the subset of first order predicate calculus. Such a semantic network of geographic space represents the foundation for semantic data analyses and data integration in distributed information systems. Our application is based on the methods of machine learning and use of the Prolog programming language.
Mathematical modelling is a common approach when assessing debris-flow hazards. In this study on the mathematical modelling of debris flows, we applied the widely used Flo2D model. The high accuracy ...of the input parameters is essential for obtaining acceptable results. The numerimi grid in the area of the debrisflow movement is generated from topographic data. The aim of our research was to assess the usefulness of public data for debrisflow-modelling and to compare this data to the LiDAR-derived data. In Slovenia, DEM 5 and DEM 12.5 are publicly available data. However, the morphological accuracy of these dataseis is questionable because of their development methods and their low morphologic resolution. A better solution is LiDAR-derived data with higher resolutions and a multiple options for further improvements with different methods and algorithms. The results with LiDAR data are more accurate-, the torrential channel is better expressed. One downside of LiDAR data is its high price, which prevents wider usage of more precise data. Another downside is the much longer computational times of the model. More precise data means a more agitated surface of the computational grid, which results in shorter computational steps to ensure numerical stability. Methods for LiDAR-derived DEMs improvements are proposed in this study. With modified data, computational times are much shorter and results are even more precise than with non-modified DEMs.
Geographic information systems have been applied on the World Wide Web with different approaches and there is a need to recognize how different groups of users conceptualize the domain of geographic ...space. In our research, we present an attempt to model a semantic reference system in a semantic web by the concept of global geo-ontology. Taxonomy is based on general knowledge representation as physical and conceptual shapes, simultaneously with basic and advanced human activities. Developed ontology includes 588 concepts on five levels and is extendable. Within such a structure, the rules as independence of location, time frame and culture are respected.
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