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Topographic information in cultural and natural heritage visualization and animation Mapping and Visualization Techniques If information is available in digital form, any combination of data can be visualized in any views and scales necessary for the observer. Vector maps or orthophotos can be shown separately or as a combined product. If combined with the DEM, virtual views from any observation point on the surface or above can give an imagination of a present, past or future landscape (Fig. 2). Not every relevant detail can be seen in images, however. Cultural heritage objects may be too small, covered by soil or vegetation, or even removed for conservation or museum presentation. To show those objects, 2D- or 3D-symbols can be generated and stored in separate overlays. If included in a multimedia or GIS application, these symbols can be switched on and off depending on thematic attributes or historical periods, and linked with further text or graphical information (Fig. 4).  Fig. 4: Screenshot from a multimedia project (Eifel, Germany). Archaeological information is linked to symbols in a virtual landscape. Perspective views, based on images draped over DEMs, do not give a proper visualization of buildings, however, since standard DEMs, being only 2½ -dimensional, can not handle vertical surfaces and the images do not provide the necessary texture. Here, separate data have to be obtained. This can be a very large task, but the expenditure can be reduced when only relevant structures are shown and when their geometry is reduced to typical features. For example, for a virtual flight over a 40 km part of the Rhine River (which will be proposed as a World Heritage Cultural Landscape) we have produced simplified 3D appearances for many castles and ruins which can be placed in the landscape model. They can also be considered as 3D symbols, and we experiment with a virtual flight where those symbols will appear in a scale larger than the scale of the landscape model (Fig. 5).  Fig. 5: 3D symbol of a castle placed in virtual landscape. Symbol is based on the real appearance of the castle and shown in larger scale than topography. (Holtkamp 2000). Finally, landscape changes, caused by nature or man-made, can be modeled if multitemporal information is available. Consecutive images or videos, showing the historical change, are very useful for understanding natural and cultural landscape development. Landuse changes can be shown using different overlays. If elevation changes took place (e.g. erosion or earthworks), the DEM itself has to be changed depending on time. Since appropriate tools for DEM modeling are not available in software products, own procedures were developed and applied for a video showing the geological (mainly volcanic) and cultural (landuse changes, heavy quarrying) changes of a landscape (Böhler et. al. 1999, 2000). The video is presented in the poster session of this workshop. Landscape Management and Monitoring Considering the size and complexity of a landscape, adequate tools have to be provided for its management. After UNESCO had introduced legal instruments to recognize and protect cultural landscapes of outstanding universal value, and several cultural landscapes were included in the World Heritage list, it was soon realized, that "the resources management, e.g. the management and protection of the cultural values for which these sites have been inscribed , has to be improved" (Roessler 2000). It is obvious that surveying and mapping procedures, based on sufficiently complete and updated databases, are needed to document and monitor the sites and to allow predictive modeling of future developments. The role of Geographic Information Systems is of special importance in this context (UNESCO 1999).  Fig. 6: Three frames from a video showing the development of settlements over 100 years (Eifel, Germany). Settlement boundaries were digitized from old maps and superimposed on a recent satellite image. Especially in the case of ’continuing landscapes’, where a large number of authorities and private owners may have to co-ordinate their actions and political decisions have to be prepared and mediated, planning and modeling future developments is of utmost importance. Changes within the landscape or in its neighborhood may impair or even destroy its cultural value. This is why UNESCO demands ’reactive monitoring’ and periodic reporting to ensure that World Heritage Sites remain undestroyed and can be kept on the World Heritage List. Conclusions Documenting cultural landscapes or landscapes around objects of cultural heritage has often been neglected because the surveying and mapping expenditure was too high. With modern surveying and visualization techniques, landscape documentation and visualization has become affordable and rewarding. Especially when combined with geographic information systems, virtual landscapes can be a powerful means to describe a landscape and to monitor and manage its conservation and development. References
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