EFFICIENT 3D DOCUMENTATION OF NEPTUNE FOUNTAIN IN THE PARK OF SCHÖNBRUNN PALACE AT MILLIMETER SCALE
3D documentation of cultural heritage is commonly based on image sensors or laser scanning. Respective sensors and software tools have been improved significantly in recent years concerning both automation and accuracy. Considering the documentation of huge objects with high richness in detail requires a huge effort. Close-range scanners offer the highest accuracy, however, their restricted field-of-view and their limited maximum measurement distance make numerous scanning positions necessary, thus significantly increasing the effort for data acquisition and processing. This is similar if image processing is used for aiming at mm-accuracy. For this, several hundred images are typically necessary for modelling sculptures properly. Consequently, both methods are not applicable for huge objects with an extension of several tens of meters and with a highly structured surface. Within this contribution, we describe a workflow for data acquisition and processing of the Neptune Fountain in the park area of the UNESCO World Heritage Site Schloß Schönbrunn in Vienna, Austria. Some 5 billion points were acquired from 230 scanning positions within four days using a phase-shift laser scanner. Highly automated processing of this data resulted in a triangulation model with an absolute accuracy of less than 5 mm for non-translucent materials. Problems at the translucent marble structures are analysed and a textured 3D model of a portion of the object for the application on mobile devices is presented.