3D digitization of a large model of imperial Rome

This paper describes 3D acquisition and modeling of the "Plastico di Roma antica", a large plaster-of-Paris model of imperial Rome (16×17 meters) created in the last century. Its overall size demands an acquisition approach typical of large structures, but it is also characterized by extremely tiny details, typical of small objects: houses are a few centimeters high; their doors, windows, etc. are smaller than 1 cm. The approach followed to resolve this "contradiction" is described. The result is a huge but precise 3D model created by using a special metrology laser radar. We give an account of the procedures of reorienting the large point clouds obtained after each acquisition step (50-60 million points) into a single reference system by means of measuring fixed redundant reference points. Finally we show how the data set can be properly divided into 2×2 meters sub-areas for allowing data merging and mesh editing.