Generation of 3D/4D Photorealistic Building Models. The Testbed Area for 4D Cultural Heritage World Project: The Historical Center of Calw (Germany)

3D/4D photorealistic models present great advantages in different applications like preservation of the cultural heritage, urban planning, public management, etc. For getting precise and reliable models, the geometries should be accurate and the textures wrapped with optimal quality imagery. The systems of terrestrial laser scanner (TLS) are one of the most reliable techniques for capturing accurate data. However, these systems have some drawbacks like the missing data in certain areas or the lack of information about textures. Photogrammetric images contain the required textures and can be used to generate dense point clouds by dense image matching. In this way, the combined use of photogrammetric images and laser systems is symbiotic, being thus able to exploit the advantages of both technical methods. If the textures are wrapped using historical photos, the temporal dimension is incorporated to the model (4D), making it possible to reconstruct the past. However, historical photos have some additional drawbacks like the lack of metadata and the fact that they have been captured from only a few positions.