| description |
Urban models can be collected area covering and efficiently based on
aerial data like stereo images or LIDAR. While a large number of
applications like simulations are already feasible based on the
available three-dimensional building representations, a further
quality improvement is required for some other tasks. Especially, if
very realistic visualisations from pedestrian viewpoints have to be
generated, the quality and amount of detail, which is available for
urban models generated from aerial data has to be improved. As an
example, due to the viewpoint restrictions of airborne platforms,
image texture for the facades of the buildings frequently is not
available from airborne sensors. Since this information is crucial
to improve the visual appearance of urban models for pedestrian
perspectives, alternative data sources have to be applied. Thus,
image texture for the faces of existing building models is
frequently generated based on manual mapping of terrestrial images.
As it will be discussed within the paper, the efficiency of the
manual mapping process can be increased considerably by the
application of panoramic scenes. If these panoramic scenes are
collected from a high-level system based on a rotating CCD line
scanner, large areas are covered at high resolution and superb image
quality. Thus, the processing of a single scene is sufficient to
extract texture for a considerable number of buildings. After the
mapping of terrestrial image against the available building model is
defined, the process of texture extraction and placement can be
realized very efficiently if the functionality of 3D graphics
hardware is used. In contrast to the application of standard
viewers, this technique allows to model even complex geometric
effects like self-occlusion or lens distortion. By these means a
very fast and flexible on-the-fly generation of façade texture
using real world imagery is feasible.
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