Replication of Marble Exhibits Using Photogrammetry and Laser Scanning (or How to Forge Exhibits)

The replication (exact copying) of marble museum exhibits using marble powder is being analysed in this paper. Optical and laser scanners has been used to collect dense point clouds, which form a three-dimensional computer model. This model has been used to physically reconstruct the object using rapid prototyping techniques. Model of objects from 0.15m up to 1.86m have been replicated as examples. The procedure and the problems confronted with the solutions given on each case, along with experience gained are being discussed. Problems concerning accuracy, number of points and formulation of the model are reported. Comparison of the systems in terms of accuracy, speed and functionality is the main concern of this paper. Particular reference is being done to the optical scanner. In order to minimize the number of the photographs, maximize the data collection rate and automate as much as possible the procedure, a slide projector with a grid is being used as the second camera. The process is depended on machine vision techniques, which automates line extraction and point cloud calculation thus reducing time, but deteriorating a bit the accuracy. The physical reproduction of Kouros, a 1.86 meter statue is being examined as an example.