International cooperation and technology transfer

Fras, Mojca Kosmatin

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Monograph

Persistent identifier:: 856490555

Author:: Fras, Mojca Kosmatin

Title:: International cooperation and technology transfer

Sub title:: Ljubljana, Slovenia, February 2 - 5, 2000 : proceedings of the workshop

Scope:: VI, 163 Seiten

Year of publication:: 2000

Place of publication:: London

Publisher of the original:: RICS Books

Identifier (digital):: 856490555

Illustration:: Illustrationen, Diagramme

Language:: English

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

Publisher of the digital copy:: Technische Informationsbibliothek Hannover

Place of publication of the digital copy:: Hannover

Year of publication of the original:: 2016

Document type:: Monograph

Collection:: Earth sciences

Chapter

Title:: INTERACTIVE VISUALIZATION OF TERRAIN MODELS AND ORTHOPHOTOS. Lionel Dorffner, assistant professor

Document type:: Monograph

Structure type:: Chapter

52 together with an orthophoto as texture source more than 99 percent of the data is needed to store photo texture in an uncompressed way. Experiments prove that lossy compression techniques, such as JPEG, shrink the original texture files to some 5 percent of its former size without significant loss of quality. Although uncompressed during visualization the texture can be stored in small files thus enabling faster loading from disk. Decompression in memory is much faster than disk reading. The resulting loss of information and accuracy is acceptable, as the images are used mainly for visualization and animation purposes. 3 IMPLEMENTATION More than 25 years ago a modular program system (SCOP) for the generation and management of high-quality DTM data with a hybrid data structure was developed at our institute in Vienna (Institute of Photogrammetry and Remote Sensing [http://www.ipf.tuwien.ac.at]) in very close cooperation with INPHO GmbH in Stuttgart (Germany) [http://www.inpho.de/scop.htm]. In the course of the years the functionality of SCOP has continuously been extended and improved. The DTM is integrated in SCOP as the central data base, and so it is possible to derive in a very flexible way (using additional modules) numerous follow-up products. Some important modules are: ISOLINES (derives isolines from any digital surface described in the data structure of SCOP, this can be elevation models, slope models or difference models) DOP (generation of digital orthophotos based on the high quality DTM data structure) PERSPECT (produces static 3D views of the DTM in form of a perspective representation or a parallel projection) PROFILE (interpolates single heights and height profiles - longitudinal, parallel, cross-sections - for any polygon position within the DTM area) TDM (management and archiving of huge amounts of terrain data using a relational data base system with efficient geometric queries) As a consequence of the increasing demand for interactive visualization an additional module to SCOP has been developed and implemented. This new Animated Terrain Model (ATM) tool provides an easy way for preparing and exporting SCOP DTM data for interactive 3D visualization. If the exported area is also covered - maybe only partly - by an orthophoto or an orthophoto mosaic this image data can be mapped as texture information over the animated terrain model. Areas without texture information are visualized as gray shading. In addition the predefinition of viewpoints and even a whole camera path for an automatic flight through the model can be done graphically in ATM (Figure 2). Figure 2 User interface of ATM showing coded DTM and defined flight path. The data is then exported using the data format VRML97. VRML is an acronym for "Virtual Reality Modeling Language". It is the international standard (ISO/IEC 14772) file format for describing interactive 3D worlds and objects on the Internet [Carey R., Bell G., 1997]. It is in fact the 3D analogy to HTML. This means that VRML serves as a simple, multi platform language for publishing 3D Web pages. For visualizing such data a VRML viewer is necessary. This viewer can either be a standalone program or it can be integrated as plug-in into a HTML browser. There are a lot of such viewers on the market (CosmoPlayer™, CASUSPresenter™, VRwave™, WorldView , ...) for every current operating system, most of them as freeware [The VRML Repository]. Therefore, no additional cost may arise for the final user. The VRML world enables the users to interactively examine and visualize their data. As this data format is used on the Internet it is basically designed for a small amount of data. Therefore, special attention has been given to managing large data set, that have to be dealt with if DTMs or orthophotos are examined and visualized interactively. In order to achieve this goal all requirements for efficient visualization mentioned above have been realized in ATM. The whole DTM model is split up into Tiles, each one stored in different levels of detail. The image pyramid of the orthophoto is also divided using the same Tile limits. The number of grid points and the number of pixels within one Tile as well as the degree of data reduction for the LODs can be set by

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