The detection of peaks (summits) as the upper parts of mountains and the delineation of their shape is commonly confirmed by inspections carried out by mountaineers. In this study the complex task of ...peak detection and shape delineation is solved by autometric methodological procedures, more precisely, by developing relatively simple but innovative image-processing and spatial-analysis techniques (e.g., developing inventive variables using an annular moving window) in remote sensing and GIS domains. The techniques have been integrated into automated morphometric methodological procedures. The concepts of peaks and their shapes (sharp, blunt, oblong, circular and conical) were parameterized based on topographic and morphologic criteria. A geomorphologically high quality DEM was used as a fundamental dataset. The results, detected peaks with delineated shapes, have been integratively enriched with numerous independent datasets (e.g., with triangulated spot heights) and information (e.g., etymological information), and mountaineering criteria have been implemented to improve the judgments. This holistic approach has proved the applicability of both highly standardized and universal parameters for the geomorphologically diverse Kamnik Alps case study area. Possible applications of this research are numerous, e.g., a comprehensive quality control of DEM or significantly improved models for the spatial planning proposes.
This paper describes in detail the applicability of the developed ground-penetrating radar (GPR) model with a kinematic GPR and self-tracking (robotic) terrestrial positioning system (TPS) surveying ...setup (GPR-TPS model) for the acquisition, processing and visualisation of underground utility infrastructure (UUI) in a real urban environment. The integration of GPR with TPS can significantly improve the accuracy of UUI positioning in a real urban environment by means of efficient control of GPR trajectories. Two areas in the urban part of Celje in Slovenia were chosen. The accuracy of the kinematic GPR-TPS model was analysed by comparing the three-dimensional (3D) position of UUI given as reference values (true 3D position) from the officially consolidated cadastre of utility infrastructure in the Republic of Slovenia and those obtained by the GPR-TPS method. To determine the reference 3D position of the GPR antenna and UUI, the same positional and height geodetic network was used. Small unmanned aerial vehicles (UAV) were used for recording to provide a better spatial display of the results of UUI obtained with the GPR-TPS method. As demonstrated by the results, the kinematic GPR-TPS model for data acquisition can achieve an accuracy of fewer than 15 centimetres in a real urban environment.
► Test recognition method for monitoring the invasive Robinia pseudacacia. ► Low-cost remote-sensed sources sufficed. ► Digital orthophotos taken in the flowering period yielded the best results. ► ...Filtering the data with forest extent information (GIS layer) improved the results. ► Specially adapted measure outperforms AUC in assessing model performance.
Monitoring the spread of invasive species is crucial for nature conservation; however regularity can only be assured if cost-effectiveness can be achieved. We aimed at testing low-cost remote sensing sources and simple methodology for recognising the invasive species Robinia pseudacacia and thus founding a monitoring scheme. A study area with mixed wooded stands containing R. pseudacacia has been selected for this purpose in NE Slovenia. Four different sources (Landsat ETM and airborne orthophotos from summer and spring) were tested together with a filtering for forested areas. Filtering was based either on Landsat information or on a forest polygon layer as alternatives. Generalised linear models were constructed in a training window within the study area to establish a statistical rule of recognition for the species based on spectral information. Models were tested both within and outside the training window for accuracy. As means of accuracy assessment both the well-established AUC and the specially adapted Jaccard index have been applied.
The best and most reliable recognition was achieved by using the spring orthophoto, in which the species was captured in flower, combined with a GIS filtering by a forest vector layer. The superiority of this combination was especially striking when tested over the full study area. The Jaccard index appeared to be more sensitive in discrimination between models. Thus we conclude that even spectrally less detailed data sources may provide a basis for successful monitoring if the phenology of the target species is also considered.
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 2.5D 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 LAStools 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.
A novel method called multidirectional visibility index (MVI) has been developed and verified. The MVI improves standard cartographic analytical shading with a number of enhancements to topographic ...detail and prominent structures, i.e. the portrayal of flat areas in lighter tones, the accentuation of morphologic edges, and the multiscale visualisation of morphologic terrain features. The procedure requires a digital elevation model (DEM) and involves the following steps: visibility mask computation; the respective multidirectional altering of the azimuth and elevation angle; the generation of continuous grid MVIs that indicate upper/lower views, quasi-slope, and relative relief; and an appropriate visualisation of the relevant MVI as a standalone technique or in combination with standard hill-shaded relief. The modelling parameters are robust and therefore highly adaptive to different landforms.
Terrestrial talus slopes are a common feature of mountainous environments. Their geomorphic form is determined by their being constituted of scree, or similar loose and often poorly sorted material. ...Martian talus slopes are governed by the different nature of the Martian environment, namely: weaker gravity, the wide availability of loose material, the lack of fluvial erosion and the typicality of large escarpments; all these factors make talus slopes a more striking areomorphic feature on Mars than on Earth. This paper concerns the development of a numerical geomorphometric analysis, parameterization and detection of the talus slopes method. We design inventive variables, a multidirectional visibility index (MVI) and a relief above (RA) and propose two techniques of talus slope extraction: ISOcluster and progressive Boolean overlay. Our Martian digital terrain model (DTM) was derived from the ESA Mars Express HRSC imagery, with a resolution of 50m. The method was tested in the study areas of Nanedi Valles and West Candor Chasma. The major challenge concerned the quality of the DTM. The selection of robust variables was therefore crucial. Our final model is to a certain degree DTM-error tolerant. The results show that the method is selective concerning those slopes that can be considered to constitute a talus slopes area, according to the visual interpretation of HRSC images. Based on an analysis of the DTM, it is possible to infer various geological properties and geophysical processes of the Martian and terrestrial environments; this has a range of applications, such as natural hazard risk management.
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•Geomorphometric analysis, parameterization and detecting of the talus slopes.•Inventive variables: multidirectional visibility index (MVI) and relief above (RA).•ISOcluster and novel progressive Boolean overlay model of talus slopes.•The selection of robust variables is more important than the modeling method used.•The procedure is DTM-error tolerant with inferences to geophysical processes.
In this article we analyze a well-known and extensively researched problem: how to find all datasets, on the one hand, and on the other hand only those that are of value to the user when dealing with ...a specific spatially oriented task. In analogy with existing approaches to a similar problem from other fields of human endeavor, we call this software solution 'a spatial data recommendation service.' In its final version, this service should be capable of matching requests created in the user's mind with the content of the existing datasets, while taking into account the user's preferences obtained from the user's previous use of the service. As a result, the service should recommend a list of datasets best suited to the user's needs. In this regard, we consider metadata, particularly natural language definitions of spatial entities, a crucial piece of the solution. To be able to use this information in the process of matching the user's request with the dataset content, this information must be semantically preprocessed. To automate this task we have applied a machine learning approach. With inductive logic programming (ILP) our system learns rules that identify and extract values for the five most frequent relations/properties found in Slovene natural language definitions of spatial entities. The initially established quality criterion for identifying and extracting information was met in three out of five examples. Therefore we conclude that ILP offers a promising approach to developing an information extraction component of a spatial data recommendation service.
V članku je predstavljena inovativna različica pristopa obrnjenega učenja, ki temelji na intenzivni uporabi geomedijev pri poučevanju geografije in geoinformatike. Študentje ocenjujejo kakovost ...kartiranja na podlagi ISO standarda. Rezultati kažejo, da so posamezniki bistveno boljši v primerjavi s skupinami pri tistih nalogah, ki zahtevajo kritično presojo, poglobljeno razumevanje snovi in kreativno razmišljanje. Skupine so uspešnejše pri ugotavljanju unikatnih razlik, kjer prihaja do izraza sinergijski efekt kot posledica sodelovalnega učenja.
This paper describes in detail the development of a ground-penetrating radar (GPR) model for the acquisition, processing and visualisation of underground utility infrastructure (UUI) in a controlled ...environment. The initiative was to simulate a subsurface urban environment through the construction of regional road, local road and pedestrian pavement in real urban field/testing pools (RUTPs). The RUTPs represented a controlled environment in which the most commonly used utilities were installed. The accuracy of the proposed kinematic GPR-TPS (terrestrial positioning system) model was analysed using all the available data about the materials, whilst taking into account the thickness of the pavement as well as the materials, dimensions and 3D position of the UUI as given reference values. To determine the reference 3D position of the UUI, a terrestrial geodetic surveying method based on the established positional and height geodetic network was used. In the first phase of the model, the geodetic network was used as a starting point for determining the 3D position of the GPR antenna with the efficient kinematic GPR surveying setup using a GPR and self-tracking (robotic) TPS. In the second phase, GPR-TPS system latency was quantified by matching radargram pairs with a set of fidelity measures based on a correlation coefficient and mean squared error. This was followed by the most important phase, where, by combining sets of “standard” processing routines of GPR signals with the support of advanced algorithms for signal processing, UUI were interpreted and visualised semi-automatically. As demonstrated by the results, the proposed GPR model with a kinematic GPR-TPS surveying setup for data acquisition is capable of achieving an accuracy of less than ten centimetres.
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