Abstract
The drawings as critical information for ancient Roman study often include some mistakes or divergence. A large difference was confirmed when the map of Pompeii and Ostia, the drawings of floor mosaics and the plans of houses were compared to the drawings produced by a laser scanner. These incorrect records and drawings could eventually lead us to not only loss of new study opportunity but also incorrect study results. The existing mosaic plans could be recorded differently due to a prejudiced impression and the plans might be completed as they are supposed to be in a restored drawing. In the plan of Insula IX of Regio III, the thickness of a half number of walls is recorded differently and the locations of the center line of the walls are partially unmatched. An existing surveying method would easily be reflected by consciousness of a surveyor.
