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Wyszukujesz frazę "DTM generalization" wg kryterium: Temat

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    Wyświetlanie 1-3 z 3
    Tytuł:
    Wieloskalowe modelowanie rzeźby terenu. Cz. 2
    Multiscale modelling of relief. Part 2
    Autorzy:
    Kochman, M.
    Olszewski, R.
    Powiązania:
    https://bibliotekanauki.pl/articles/204538.pdf
    Data publikacji:
    2005
    Wydawca:
    Polskie Towarzystwo Geograficzne
    Tematy:
    generalizacja NMT
    wieloskalowość
    linia strukturalna
    structure lines
    DTM generalization
    multiscaling
    Opis:
    W drugiej części artykułu omówiono wybrane koncepcje generalizacji numerycznego modelu rzeźby terenu, ze szczególnym uwzględnieniem metody wagowanej filtracji lokalnej opartej na uogólnieniu linii strukturalnych. Zaproponowano także koncepcję budowy wieloskalowego NMT o strukturze hierarchicznej, umożliwiającą monoskalową reprezentację modelu rzeźby na określonym poziomie uogólnienia.
    The concept of hierarchical model of relief is a logical conclusion of the idea of a multi representation topographic database. It permits a combined analysis of all the components of the environment and uncovers new possibilities in preserving the integrity of spatial constraints between the model of terrain and other thematic layers (primarily river network). It is possible due to, among other factors, defining of spatial relations between particular objects and object classes. It also provides a new way of looking at the process of relief generalization understood as an approximation of the relief model preserving topological relations, and not as a simplification of contour lines. The basic feature of the generalization of relief should be the preservation of its structure (morphological skeleton). What seems important for the construction of multi scale DTM is not only a hierarchical approach to relief modelling but also the method of approximation of source data. Simple algorithms of DTM generalization such as the conversion of TIN model into regular GRID structure of certain spatial resolution and the application of global filtration allow for a relatively low reduction of complexity of the source model. The proposed concept of hierarchical model preparation through iterative elimination of points from the data source combines elements of local filtration and heuristic approach. In the conducted research it was assumed, that while building the hierarchical structure of DTM model one should define relief structural lines and assign to them appropriate numeric weights. The analysis bases on the division of source data of the model into structural and mass points. In the process of generalization the points are removed according to the combined evaluation of several criteria: their vertical significance (established locally), their density (horizontal significance), and for structural points also by the weight of structural lines and local curvature of those line (established horizontally as well as vertically). The selection of relevance of particular criteria is fully parameterized, permitting a free assignment of weight factors. Hierarchical (multi scale) model of relief can be adapted to the scale of presentation chosen by the user, while retaining the relief structure relevant for that level of generalization. Suggested algorithms make it possible to preserve significant topological relations between structural elements of relief.
    Źródło:
    Polski Przegląd Kartograficzny; 2005, T. 37, nr 4, 4; 267-273
    0324-8321
    Pojawia się w:
    Polski Przegląd Kartograficzny
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Wieloskalowe modelowanie rzeźby terenu
    Multiscale modeling of relief
    Autorzy:
    Kochman, M.
    Olszewski, R.
    Powiązania:
    https://bibliotekanauki.pl/articles/204163.pdf
    Data publikacji:
    2005
    Wydawca:
    Polskie Towarzystwo Geograficzne
    Tematy:
    teren
    rzeźba terenu
    model numeryczny
    multiscale generalization of DTM
    structure lines
    Opis:
    W artykule omówiono wybrane koncepcje generalizacji numerycznego modelu rzeźby terenu (NMT), ze szczególnym uwzględnieniem metody heurystycznej opartej na uogólnieniu linii strukturalnych terenu. Przedstawiono także zróżnicowane sposoby wyznaczania linii strukturalnych i ich znaczenie dla wieloskalowego modelowania rzeźby terenu oraz generalizacji NMT.
    In order to automatize the process of generalization of DTM (Digital Terrain Model) in TDB (Topographic Data Base), information about relief should be recorded in such a way, as to preserve real location of characteristic key forms and structure lines. Automatic generalization of DTM should involve generalization of database rather than graphic simplification of contour lines. Among the existing methods of DTM generalization one can distinguish various types of filtering (global, local) and heuristic approach based on a concept of generalization of structure lines. It uses digital operators in interactive cooperation between operator and the digital system. Here, generalization bases on the approximation of source SLM (structure line model) through the use of classic generalization methods such as, among others: magnification, deletion, combination, and simplification of single structure lines, followed by recomposition of secondary DTM basing on the resulting SLM. In the conducted research it was assumed, that for the composition of a hierarchical (multiscale) DTM basing on a generalization of significant morphological forms it is especially important to properly establish structure lines which constitute the topographic ..skeleton" of terrain. These lines were established basing on the existing topographic maps as well as on the analysis of TIN and GRID model. The aim was to see if it was possible to fully automatically determine structure lines basing on irregular (or regular) source data including no additional information on structural forms. Most algorithms which determine structure lines of relief basing on the regular model involve advanced analysis of potential surface flow accumulation. The research applied a modified D8 algorithm implemented in GM Grid 5,2 module, which is a functional extension of GeoMedia Professional package by Intergraph. To establish erosion network (drainage lines) it is vital to determine a threshold of accumulated flow, over which drainage network becomes a stream. Although the process is fully automatic, subjective setting of such threshold significantly varies the results. Authors of the concept of so-called extended Morse-Smale's decomposition (E. Danovaro L. DeFloriani, P. Magillo, M. Mesmoudi, E. Puppo 2003) claim that generalization of automatically determined structure lines allows for hierarchical DTM generalization, preserving significant topological relations. The research results do not support that hypothesis. Because the actual structure lines were not taken into consideration, in the process of standard Delaneuy's triangulation there appear triangles with edges crossing structure lines. It appears that although DTM generalization (or its hierarchical composition) can be successfully executed through the generalization of structure lines, the automatization of the process of determining these lines does not yield expected results. The need to determine structure lines through direct surveying, e.g. with photogrammetric techniques is therefore justified. Basing on thus determined ..skeleton" it is possible to properly generalize the model of relief, while preserving significant topological relations.
    Źródło:
    Polski Przegląd Kartograficzny; 2005, T. 37, nr 3, 3; 171-184
    0324-8321
    Pojawia się w:
    Polski Przegląd Kartograficzny
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Systemy wnioskowania rozmytego (FIS) jako narzędzie nieliniowej generalizacji numerycznego modelu terenu
    Fuzzy inference systems (FIS) as a tool of non-linear generalization of digital terrain models
    Autorzy:
    Olszewski, R.
    Powiązania:
    https://bibliotekanauki.pl/articles/204380.pdf
    Data publikacji:
    2006
    Wydawca:
    Polskie Towarzystwo Geograficzne
    Tematy:
    generalizacja
    filtracja nieliniowa
    system wnioskowania rozmytego
    FIS
    numeryczny model terenu
    generalization
    non-linear filtering
    fuzzy inference system
    digital terrain model (DTM)
    Opis:
    W artykule omówiono zagadnienie zastosowania systemów generalizacji danych przestrzennych opartych na logice rozmytej do modelowania rzeźby terenu na różnym poziomie uogólnienia.
    Classic filtering methods of raster data (e.g. digital terrain model), such as median or gaussian filtering level the result surface, and consequently flatten the end results. A significant modification of results' range, understood as narrowing of the scope of relative altitudes in the test area, is not the only side effect of the process of DTM generalization. Gaussian filtering, and especially non-linear median filtering leads to non-linear morphometric modifications of generalized terrain relief. Structural forms common for high mountain relief, such as ridge lines and deeply cut river valleys are flattened more than other forms. In the article the author attempts to elaborate a non-linear method of raster data filtering by defining the objective generalization rules of local character. These rules determine the global process of cartographic generalization of raster-type data. In order to build a database which would enable the realization of the process of spatial data generalization, fuzzy inference systems (FIS) are applied. Application of fuzzy logic makes it possible to define generalization rules for non-linear filtering of a digital terrain model recorded in the form of an altitude matrix. In the discussed context FIS can be interpreted as a non-linear digital terrain model transformation. Compared to other non-linear modeling techniques FIS has many advantages: - it keeps the parameters of source data distribution (slant, range, etc.,) - enables open and easy to interpret definition of rules in the data base (in relation to scale, purpose, cartographic school, etc.), - it bases on linguistic variables, which facilitates the understanding of the generalization process, - it facilitates scalability of the results through parametrization of the membership function. Application of fuzzy logic and generalization systems using fuzzy inference makes it possible to automatize the generalization process while preserving subjectivity of cartographic generalization. The final effects depend on the FIS database created by the researcher.
    Źródło:
    Polski Przegląd Kartograficzny; 2006, T. 38, nr 4, 4; 316-325
    0324-8321
    Pojawia się w:
    Polski Przegląd Kartograficzny
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
      Wyświetlanie 1-3 z 3

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