Proceedings, XXth congress: Proceedings, XXth congress

Altan, M. Orhan

Bibliographic data

Multivolume work

Persistent identifier:: 1663674213

Title:: Proceedings, XXth congress

Sub title:: Istanbul, 12 - 23 July 2004

Year of publication:: 2004

Place of publication:: Istanbul

Publisher of the original:: [Verlag nicht ermittelbar]

Identifier (digital):: 1663674213

Language:: English

Additional Notes:: Erscheinungsdatum des Originals ist aus dem Copyrightjahr ermittelt.; Auch bezeichnet als XXth International Congress for Photogrammetry and Remote Sensing

Editor:: Altan, M. Orhan

Corporations:: International Society for Photogrammetry and Remote Sensing, Congress, 20., 2004, Istanbul; International Society for Photogrammetry and Remote Sensing, Commission Primary Data Acquisition

Adapter:: International Society for Photogrammetry and Remote Sensing, Congress, 20., 2004, Istanbul; International Society for Photogrammetry and Remote Sensing, Commission Primary Data Acquisition

Founder of work:: International Society for Photogrammetry and Remote Sensing, Congress, 20., 2004, Istanbul; International Society for Photogrammetry and Remote Sensing, Commission Primary Data Acquisition

Other corporate:: International Society for Photogrammetry and Remote Sensing, Congress, 20., 2004, Istanbul; International Society for Photogrammetry and Remote Sensing, Commission Primary Data Acquisition

Document type:: Multivolume work

Volume

Persistent identifier:: 166368779X

Title:: Proceedings, XXth congress

Scope:: IV, 226 Seiten

Year of publication:: 2004

Place of publication:: Istanbul

Publisher of the original:: [Verlag nicht ermittelbar]

Identifier (digital):: 166368779X

Illustration:: Illustrationen, Diagramme

Signature of the source:: ZS 312(35,B8)

Language:: English

Additional Notes:: Erscheinungsdatum des Originals ist aus dem Copyrightjahr ermittelt.

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

Editor:: Altan, M. Orhan

Corporations:: International Society for Photogrammetry and Remote Sensing, Congress, 20., 2004, Istanbul; International Society for Photogrammetry and Remote Sensing

Adapter:: International Society for Photogrammetry and Remote Sensing, Congress, 20., 2004, Istanbul; International Society for Photogrammetry and Remote Sensing

Founder of work:: International Society for Photogrammetry and Remote Sensing, Congress, 20., 2004, Istanbul; International Society for Photogrammetry and Remote Sensing

Other corporate:: International Society for Photogrammetry and Remote Sensing, Congress, 20., 2004, Istanbul; International Society for 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:: VIRTUAL ENVIRONMENTS IN PLANNING AFFAIRS Getting closer to geographic data, a better way! Mohammed Abdul Mannan, Bogdahn Juergen.

Document type:: Multivolume work

Structure type:: Chapter

standing lent, and ial scale ance the inge and ouble in ormance et based ) display project, lata. The d by the st future sage etc. mendous in Web- jased on model of ind non- process. an point om GIS ty (VR). t allow ions and JR offers ta. Users planned In most viewing. result in are not | analysis language :cess and his paper Various 3D/VR- “rst, we | section. > Virtual International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences, Vol XXXV, Part B-YF. Istanbul 2004 2. WEB 3D An important factor in a 3D GIS is remote access to the data. Recent developments on the Web, i.e. VRML make possible visualization and interaction with 3D models. The exploration of the 3D worlds in the VR browsers ensures a certain level of virtual reality techniques. Existing VRML, HTML and other Web standards and software modules allow the development of GUI with limited effort, relying on some operations provided already by browsers. Therefore VRML and HTML will be employed as a front-end engine to the 3D GIS model. This project was started in order to visualize the 3D city model of Stuttgart and find a way to connect the objects in the 3D scene with their attributes in the land registry dataset. The motivation was to give the user the ability to interact with the 3D scene not only by moving around, but also to have access to the attributes information by clicking on the objects. The given 3D dataset only consists of geometry information so that an algorithm had to be invented, which connects the geometry with the attributes. In the test application the conversion from the given ASCII format to VRML and the connection between the VRML objects and the attribute data is done in one step. This part is considered to be the Web3D part. Although the test application is a desktop application, it is possible to realize the concept on a website as well. The VRML viewer can be add in web pages and the application part could be realized as a Java Applet, which interacts with the viewer. 2.1 Tools The chosen developing environment is Visual C++ 6.0 and for VRML visualization, the Cortona Viewer by Parallel Graphics. Parallel Graphics supports developers by the Cortona SDK (User guide), which allows you to add the Cortona VRML Viewer into your C++ projects as an ActiveX component. There are also some event handler classes to handle mouse events, and other interface functions so you can completely interact with the viewer. To access the given land registry information in shape format the C-library “shapelib” is used (Warmerdam, 2002), which can access the geometry in the shp-file as well as the attributes in the dbf-file. 2.2 Description of the 3D objects The dataset delivered by the city administration Stuttgart, consists of several files in ASCII format storing the geometry of the buildings. These buildings are created of several parts. The 3-dimensional geometry of the roof is taken out of aerial stereo photos by semi-automatic analysis. The floor is created by intersection of the 2-dimensional outline of the building taken from the land registry and the digital terrain model. This outline should have been connected with the attributes but this connection is not supported in the ASCII files, maybe because the focus was only on visualization matters. To create the walls of the building, the 3D floor outline is connected with the roof geometry. A representative point is set inside the geometry, which is used for connection between 3D objects and the attributes in the shape-file. 2.3 Visualization The 3D geometry dataset consists of several ASCII files, which are consisting of point tables. Besides the x, y, z-coordinates each point has got the attributes houseindex, wallindex, typeofarea (roof, wall, floor). With the help of these attributes it is possible to create an IndexedFaceSet-Node (IFS). The used fields are shown in Figure 1. This VRML-Node seems to be the best solution to describe the building geometry, because it can describe complex objects, which consist of several areas, very easily. IndexedFaceSet( exposedField SFNode color NULL exposedField SFNode coord NULL field | MFInt32 coordIndex [] field | MFInt32 colorIndex [] } Figure 1. Part of VRML Specification '97 The used fields allow avoiding saving redundant points, which makes the VRML-File smaller than the corresponding ASCII- File. In the coord -field the points of the geometry are saved by the x, y, z coordinates, and in the coordIndex-field all points describing an area are listed by their index in the coord-field. So it is possible to check if a new point is already in the coord- field, if it is the point doesn't have to be saved again, only the index of the previously saved point has to be used. The algorithm to convert the ASCII information into VRML syntax only has to go through the ASCII table and read the coordinates and the attributes to decide when to create a new building (IFS-Node), a new area or when to change the color of the created area to color roof and walls differently. To be able to identify the objects, what is essential for the connection, you have to give each IFS-Node a unique identifier. In VRML it is possible to give a Node a name called DEF- Name. In the ASCII file the index for the buildings starts always with one, so if this index is used and the 3D scene consists of more than one ASCII file there is no unique identifier for the buildings. Therefore a combination of filename and index is used to form a kind of primary key for each building, which is also used for the connection later on. 2.4 Connection to attribute data The connection is done by a geometrical test. Each building of the ASCII file has got a representative point inside its geometry. The location of this point in the 2D land registry is checked and if the point lies inside of a land registry building outline, the dataset connected to this outline is considered to be connected to the 3D building. This connection is saved in a text file (see Table.1), to avoid doing this test each time a model is loaded. DEF- DBF- Name | Index Representative3D Table 1. Connection Table In this table (“connection table”) the DEF-Name of the 3D object and the corresponding dbf index of the land registry dataset are saved. The representative coordinates are saved in : addition for query or analyzing matters.

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