Experiences about Fusioning 3d Digitalization Techniques for Cultural Heritage Documentation in Cáceres Wall (spain)

In this paper we present an experience about combining 3D digitalization techniques for cultural heritage documentation. Cáceres Wall is a big and complex construction from the XII century. Caceres was declared a World Heritage City by UNESCO in 1986 because of the city's blend of Roman, Islamic, Northern Gothic and Italian Renaissance styles and the wall contains rich elements of all those époques. The wall captured is close to 900 meters long and contains seven towers and other complex elements. An urgent conservation and restoration program was promoted in order to prevent further damage in the wall. A complete 3D graphical record was needed to support this intervention. The main objective was to keep control of the main structures and to detect deformations of the wall and the towers. This was the reason why laser scanner, photogrammetry and direct measurement methods were used. On the same side, the 3D documentation of the Cáceres wall was recorded also for virtual tourism. Thus, this 3D model was made by photo texturing. The fusion of laser scanner and photogrammetry, creating a uniquely accurate 3D model, was necessary because in some sites the photogrammetry was the best technique to capture it and in other ones the laser scanner was the optimal. In this paper it is described how we have combined both techniques to conservate the accuracy and the phototexture in all the 3D models. Orthophotos, sections and other plans were created for this project. A time of flight and a homemade videogrammetry-laser, a photogrammetry camera, a total station and a GPS were used to obtain a complete 3D photorealistic model of the Cáceres Wall, the objective was to create an accuracy study of the wall healthy, capture little pieces found close to the wall and get a virtual trip around all the wall and towers.