Digital 3d Reconstruction of Scrovegni Chapel with Multiple Techniques

The use of 3D digitization and modeling in documenting heritage sites has increased significantly over the past few years. This is mainly due to advances in laser scanning techniques, 3D modeling software, image-based-modeling techniques, computer power, and virtual reality. There are many approaches currently available. The most common remains based on surveying and CAD tools and/or traditional photogrammetry with control points and a human operator. This is very time consuming and can be tedious and lingering effort. Lately, modeling methods based on laser scanners data and more automated image-based techniques are becoming available. Initially, the goal of this work was to discuss advantages and disadvantages of those 3D modeling techniques applied to a cultural heritage building, i.e. the Scrovegni chapel in Padova, Italy, by comparing the geometry and visual quality of related models for as-built documentation, restoration and interactive visualization purposes. To this aim the chapel was imaged with a color digital camera and surveyed with both different kind of laser scanners and traditional topographic instrument. Unfortunately due to the long time wasted before all requested laser scanners were available from the dealers and difficulties encountered during the subsequent 3D modeling, due to the bad quality of some range data, at the present date only the range data model is available. Therefore in this paper we will discuss only the results obtained by generating a unique 3D model of the Scrovegni Chapel using four different laser scanners: Cyrax 2500, Mensi GS 100, Optech ILRIS 3D and Riegl LMS-Z210. In order to assess the performance of these sensors when applied for cultural heritage survey, data quality, geometric accuracy, sensor noise, ease of use, speed of data collection, will be the topics of this work.