XVIIIth Congress: Commission VI

Kraus, Karl; Waldhäusl, Peter

Bibliographic data

Multivolume work

Persistent identifier:: 1667435949

Title:: XVIIIth Congress

Sub title:: Vienna, Austria 1996

Year of publication:: 1996

Place of publication:: Vienna

Publisher of the original:: Austrian Society of Surveying and Geoinformation

Identifier (digital):: 1667435949

Language:: English

Editor:: Kraus, Karl; Waldhäusl, Peter

Corporations:: International Society for Photogrammetry and Remote Sensing, Congress, 18., 1996, Wien; International Society for Photogrammetry and Remote Sensing

Adapter:: International Society for Photogrammetry and Remote Sensing, Congress, 18., 1996, Wien; International Society for Photogrammetry and Remote Sensing

Founder of work:: International Society for Photogrammetry and Remote Sensing, Congress, 18., 1996, Wien; International Society for Photogrammetry and Remote Sensing

Other corporate:: International Society for Photogrammetry and Remote Sensing, Congress, 18., 1996, Wien; International Society for Photogrammetry and Remote Sensing

Document type:: Multivolume work

Volume

Persistent identifier:: 1677550198

Title:: Commission VI

Scope:: 149, 110, 92 Seiten

Year of publication:: 1996

Place of publication:: Vienna

Publisher of the original:: Austrian Society of Surveying and Geoinformation

Identifier (digital):: 1677550198

Illustration:: Illustrationen, Diagramme

Signature of the source:: ZS 312(31,B6)

Language:: English

Additional Notes:: Die Vorlage enthält insgesamt 3 Werke: Commission VI (Seiten 1-149); National reports (Seiten 1-110); Special sessions (Seiten 1-92)

Other Title:: Enthaltendes Werk: National Reports; Enthaltendes Werk: Special sessions

Usage licence:: Attribution 4.0 International (CC BY 4.0)

Editor:: Kraus, Karl; Waldhäusl, Peter

Corporations:: International Society for Photogrammetry and Remote Sensing, Congress, 18., 1996, Wien; International Society for Photogrammetry and Remote Sensing; International Society for Photogrammetry and Remote Sensing, Commission Economic, Professional, and Educational Aspects of Photogrammetry and Remote Sensing

Adapter:: International Society for Photogrammetry and Remote Sensing, Congress, 18., 1996, Wien; International Society for Photogrammetry and Remote Sensing; International Society for Photogrammetry and Remote Sensing, Commission Economic, Professional, and Educational Aspects of Photogrammetry and Remote Sensing

Founder of work:: International Society for Photogrammetry and Remote Sensing, Congress, 18., 1996, Wien; International Society for Photogrammetry and Remote Sensing; International Society for Photogrammetry and Remote Sensing, Commission Economic, Professional, and Educational Aspects of Photogrammetry and Remote Sensing

Other corporate:: International Society for Photogrammetry and Remote Sensing, Congress, 18., 1996, Wien; International Society for Photogrammetry and Remote Sensing; International Society for Photogrammetry and Remote Sensing, Commission Economic, Professional, and Educational Aspects of Photogrammetry and Remote Sensing

Publisher of the digital copy:: Technische Informationsbibliothek Hannover

Place of publication of the digital copy:: Hannover

Year of publication of the original:: 2019

Document type:: Volume

Collection:: Earth sciences

Chapter

Title:: Commission VI

Document type:: Multivolume work

Structure type:: Chapter

Chapter

Title:: LINGUISTIC CONFUSION IN SEMANTIC MODELLING. Hans-Peter Bähr [...], Anita Schwender [...] Commission VI

Document type:: Multivolume work

Structure type:: Chapter

Bariloche National Park Hyde Park, --^ 5 Corner Part-link Specialization- link — ——- Instance link Meeting Places Figure 2: À semantic net 5 CONFUSION DUE TO UNPRECISE CONCEPTS There are concepts and terms which are overloaded with se- mantic content and therefore have become unprecise. Lin- guists call them homonyms and we use them in everyday life without being aware of this phenomenon. If we take, for ex- ample, the term "garden", we see that it means: a place where flowers are grown in "flower garden" ; it does not mean a place where children are grown in "kindergarden" but a place where very small children receive their first education. A "japanese garden" is not a garden in Japan but a certain arrangement of small ponds and bridges, trees and bushes, grass and flowers not to speak of "the Garden of Eden" the mental image of which surely differs in all of us. Only when we are asked to explain concepts do we discover how difficult it is to come to a clear definition, to choose the distinctive characteristics, those which describe the most important features or the features of interest. For example, how can "sealed surfaces" be described? Which are the key elements? Constructors involved in the construction of build- ings might understand " roofs, walls and floors covered by a waterproof material so as to keep humidity out of rooms"; urbanists would define sealed surfaces by "surfaces that do not absorb rainwater”. Photogrammetrists on the other hand might define them as surfaces having a certain spectral signa- ture. Words like " park" as represented in Figure 2, may stand for a special type of public greens, an existing area within an urban settlement or a surface foreseen in a master plan to be developed into a park in the future; moreover, the concept also covers a specially beautiful sector of the landscape which is protected by law. 10 A single term with multiple meanings can be compared to a single spectral signature which represents different land use classes in Remote Sensing (Fig 3). Figure 3 shows land use classes in a confusion matrix. Forest, meadow, swamp and park might show similar sectral signa- tures and might accordingly be assigned to the same class. An object "square" could be assigned indistinctly to "sealed surface”, " road" , "parking site", "industrial area" and "resi- dential area". The question which is the correct designation in each case is clarified through context. This kind of non-identity of the representations is an enor- mous problem for semantic modelling. 6 CONFUSION DUE TO INACCURATE DISTRIBUTION Another source of inaccuracy and uncertainties when it comes to the description of objects at the symbolic level are unsharp boundaries. In the real world sharp boundaries do not exist but are individually defined by discrete assignment. This also applies to apparently simple concepts like " build- ing". In the German cadaster, for example, not only the building, the constructed structure but the whole parcel is given the label "bebaut" (occupied by a building) no matter whether such structure occupies the whole lot or not. Instances for objects with imprecise definitions are all forms of "mixtures" (e.g. mixed forest or biotope). The distribution of species and the occurrence of disease also fall into this category. The problem of unsharp boundaries has to do with inexact quantities. When does "water" deserve the label "polluted water”? Where is the limit between "scarcely populated" area and "densely populated” area? Still worse: where are the boundaries of objects which due to their very nature do not have clear cut limits (mountains and valleys) and are therefore defined without precision? Errors resulting from the combination of this type of ele- ments are extremely difficult to model, especially when the term designating such phenomena is polysemous (has many meanings). The stochastic description of geometrical param- eters appears to be almost trivial when compared to the cor- responding modelling of semantic parameters. 7 CONFUSION DUE TO INAPPROPRIATE METHODS Linguistic difficulties with semantic modelling are not limited to terminology, to concepts and terms. They are overlapped by a phenomenon related to methodology and to graphic primitives. An example will make this clear: we use the tools of Analyti- cal Geometry for the semantic modelling of images although neither points nor lines exist in the real world or in photo- graphical images, not to mention "digital" ones. Neverthe- less we use such elements and the related models without being aware of the difference with reality. It is not surpris- ing, therefore, if such models are only able to model reality in quite an imperfect way. The convention " points and lines" belongs to the domain of the symbolic level. They are arti- ficial concepts, genially conceived and have been useful for thousands of years but they are foreign to the real world. Another example of the fact that semantic modelling still clings to concepts and metaphors which are characteristic International Archives of Photogrammetry and Remote Sensing. Vol. XXXI, Part B6. 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