V članku analiziramo metodo izgradnje digitalnega modela reliefa iz podatkov lidar na testnih primerih z območja Slovenije. Ker obe metodi temeljita na konceptih matematične morfologije, podrobneje ...predstavimo eno, medtem ko uvodoma podamo splošen pregled del na obravnavanem območju. Rezultati pokažejo, da se z obema metodama pravilno določi teren v več kot 90 odstotkih, in sta zato obe primerni za uporabo tudi na geografsko tako razgibanem območju, kot je Slovenija. Čeprav je na ravninskih območjih njuna natančnost primerljiva, opisana metoda omogoča natančnejšo izgradnjo digitalnega modela reliefa predvsem na zahtevnejših, goratih območjih z relativno strmimi in spremenljivimi nakloni ter na območjih s terasami. Tudi v teh primerih povprečna absolutna višinska napaka ni večja od 15 centimetrov ; This paper reviews two methods for digital terrain model generation from LiDAR data in test cases in Slovenia; both methods are based on concepts of mathematical morphology. A general overview of methods is given in the introduction, one of which is presented in more detail. The results show that both methods are able to correctly extract terrain points in more than 90% of the cases and are, therefore, suitable for usage even for such geographically diverse regions as Slovenia. Although the accuracy of both methods is comparable in cases of flat areas, the described method performs significantly better in problematic cases, such as hilly areas with relatively steep variable slopes, and terrains containing terraces. Even in these cases, the average absolute height error is not higher than 15 cm.
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.
Predmet raziskave je digitalni model reliefa (DMR) kot podatkovni sloj, ki podrobno opisuje obliko zemeljskega površja. DMR je digitalni zapis nadmorskih višin, predstavljen z neprekinjeno ...ploskvijo. V Sloveniji imamo dolgoletno tradicijo pri izdelavi DMR-ja, od konca 60. let prejšnjega stoletja, ko smo začeli razvijati DMR 100. Trenutno je aktualen DMR Slovenije in okolice kot zbirka digitalnih podatkov višin DMV 12,5, 25 in 100 ter izohips in skeleta reliefa. Model je bil izdelan leta 2005 po lastni metodi integracije obstoječih podatkov. V povezavi s potrebnim vzdrževanjem modela (skupaj s pretvorbo v nov koordinatni sistem) ter z razvojem novih tehnologij, kot je lasersko skeniranje in metode kontrole kakovosti podatkov, predlagamo smernice nadaljnjega razvoja. Izboljšani DMR Slovenije naj bi poleg že vključenih slojev vseboval še podatke DMV-ja 12,5 brez antropogenih vplivov, iz podatkov laserskih skeniranj izdelana DMV 1 in DMP 1 (digitalni model ploskve) ter zbirki surovih podatkov laserskih skeniranj in podatkov podvodnega reliefa ter drugih virov. / The objective of this study is the digital terrain model (DTM) as a data set that describes the shape of the Earth’s surface in a detail. The DTM is a digital record of the height values that are resembled by continuous surface. In Slovenia there is a long tradition of DTM production that started in the end of 60s when we started developing DTM 100. The present DTM is a DTM of Slovenia and its surroundings that include a database of digital elevation models DEM 12.5, 25, and 100 together with contour lines and terrain skeleton. The model was produced in 2005 with our own method of data integration. The model needs maintenance so we suggest some guidelines for further development (including transformation to a new coordinate system) that should be supported by the development of new technologies, such as laser scanning and methods of a data quality control. Besides incorporated data, the enhanced DTM of Slovenia would also include DEM 12.5 data without anthropogenic influences; laser-scanning produced DEM 1 and DSM 1 (digital surface model); a raw data database from laser scanning missions; and an underwater relief database with other data sets.
In the introductory chapter, the author explains the term “digital elevation model”~outlines the features of the 100-meter digital elevation model of Slovenia~presents relief as a component part of ...the landscape, the geographic information system, and maps~derives a special coefficient for surface undulation based on changes in altitude and inclination~describes the method for determining relationships between relief and other components of the landscape~and outlines the basic characteristics of the surface of Slovenia.The central chapters are devoted to presenting the characteristics of altitude, inclination, and surface exposition determined by the author using the 100-meter digital elevation model. On the basis of an analysis of numerous relief elements, primarily altitude, inclination, and relief coefficients, the author defines the relief units of Slovenia and calculates the relationship between relief and several other landscape elements, in particular rocks, vegetation, population, and settlement patterns.
In 2005, to the order of the Surveying and Mapping Authority of the Republic of Slovenia, the Scientific Research Centre of the Slovenian Academy of Sciences and Arts elaborated an integral system ...for data maintenance: the Digital Elevation Model with new, qualitative terrain data. The system is relatively simple and transparent. With integration of the existing data and on the basis of innovative methodology, for the territory of Slovenia and its surroundings a new digital elevation model was produced with a resolution of 12.5 m. Due to pooling of more than 25 data sets the model is a sort of collage, which is, from the metrical and geomorphological points of view, of better quality than the best source data available. A further challenge is to put the elaborated methodology and procedures of digital elevation model production into practice.
Relief maps are three-dimensional representations of the Earth’s surface. In contrast to traditional 2D maps, where the relief is represented indirectly, the relief maps are intended for direct ...representation of the relief. Such way of relief presentation is simpler and easier to understand for ordinary users. In the article, the preparation of the editorial plan is described and thepossible methods of elaboration of relief maps are presented. The method described has been used for elaboration of an insert of a relief map of the Pomurje region at horizontal scale 1 : 30,000 and at vertical scale 1 : 15,000. The work process is divided into fourphases, following in time and building one upon another: elaboration of a convex aluminium mould, thermo-vacuum process of reproduction, printing, and composition of basic elements.
Photoclinometry is a method for extraction digital elevation models from one single image on the basis of shading – in many cases it is also called shapefrom - shading method. The tested program ISIS ...is capable of making interactive photoclinometry. ISIS is developed and used especially for photographs of different space objects. It is an open-source program, which works under the Linux operating system. In this paper, the installation, handling and capabilities of ISIS are described. In detail a module for photoclinometry is described and tested. The test is made on a photograph of a part of planet Mars. The results of photoclinometry depend greatly upon parameters of photoclinomety (albedo and the photometrical function of surface) since a small change of a parameter can cause a big change in the produced DEM. With photoclinometry very accurate DEMs can never be obtained. From the test it can be concluded that results gained with photoclinometry can be used for research or orientation purposes, but never for geodetic precision. One field of possible usage in Slovenia is the old-archive CAS images of snow-covered areas.
Photogrammetric work on Triglav glacier is presented. The emphasis is on the reconstruction of the surface of the glacier by processing the old panoramic Horizont pictures. With the panoramic camera ...Horizont the Triglav glacier is pictured from two standpoints every month since 1976. In detail is described the calibration of the Horizont camera made at the University of Technology in Vienna and the outer joint orientation of Horizont and metric Rolleimetric pictures. The way how to acquire requested 3D output is presented.
Definition of a term digital terrain model that can be shortly described as 'digital description of the Earth's surface' was analysed. Meaning and usage of terms 'digital terrain model' or shortly ...DTM and 'digital elevation model' or DEM were cleared up. DEM is a simple recording of heights as attributes to a two-dimensional square grid (raster). Conception of DTM is much more; it is a complex presentation of surface that includes spot heights,structural points and lines, and other geomorphological features. Among experts and users abbreviation DEM (digital elevation model) became familiar for both, DTM and DEM, but in Slovenia DMR (it denotes DTM in English) above all. As for definition DTM contains whole definition of DEM and with regard to historical development of both concepts in Slovenia, the term 'DMR' can be used (in spite of small meaning incorrectness).
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