________CIPA 2005 XX International Symposium, 26 September – 01 October, 2005, Torino, Italy________ 1. INTRODUCTION 3D laser scanner technology, joining precision and versatility, assures survey's high quality and working time's optimization. Nowadays, it is an irreplaceable research's instrument to docu- ment, monitor, know, and, consequently, safeguard Cultural Heritage. 3D scanning points clouds elaboration permits to obtain three- dimensional digital models of artistic objects. It also allows the creation of databases and virtual museums, the digital restora- tion and the real models' reconstruction through 3D laser pro- totyping. Nowadays, in spite of fast technical progress, the application of laser scanner technology to artistic heritage's knowledge and preservation takes place only in theoretic researches. Moreover, this method actually allows to monitor and to dia- gnose architectonic organisms difficult to survey for their articu- lated geometric-formal shape and for unfavorable logistic and environmental conditions. Thanks to its peculiarities, this methodology has great potentialities in archaeological survey, not yet explored; whereas traditional systems present more diffi- culties and limits. The present essay deals with the so called roman Terme dell'Indirizzo survey, located in Currò Square, in the heart of Catania's historical centre. The building probably dates back to the late imperial age and is part of S. Maria dell'Indirizzo con- vent structure. Only ten rooms covered by original vaults and lava ashlar walls with a cement mortar core still remain of the original Thermae. The best characterized parts of the building are the Calidarium, THE LASER SCANNER FOR ARCHAEOLOGICAL SURVEY: "LE TERME DELL'INDIRIZZO" IN CATANIA A. Giuffrida, M. Liuzzo, C. Santagati, L. Andreozzi University of Catania, Engineering Faculty, Department of Architecture and Town Planning, Lab. of Architectural Photogrammetry and Survey, Viale A. Doria n 6, 95125 Catania, Italy Email: labfgmr@dau.unict.it KEY WORDS: Cultural heritage, Archaeology, Laser Scanning, 3D modeling, Texture mapping ABSTRACT 3D laser scanner technology, joining precision and versatility, assures survey's high quality and working time's optimization. Nowadays, this is the most advanced methodology to document, monitor and diagnose buildings which are difficult to survey for their articulated formal-geometric shape, unfavorable logistic and environment conditions. Thanks to its peculiarities, this methodology has great potentialities in archaeological survey, not yet explored; whereas traditional systems have more difficulties and limits. The aim of the present essay is to verify laser scanner's potentialities in surveying the so called “Terme dell'Indirizzo”, an organism of great interest for its spatial complexity and the substantial integrity's conditions of its ten rooms. The use of a high precision technology instrument, capable of providing great number of information (total cloud of approximately 24 million points) supported by suitable softwares, allows to realize the whole building's three-dimensional model by assembling sin- gle scansions into one reference system. The possibility of exploring the object's spatiality and of studying the three-dimensional model through several scales of detail has represented the first step for choosing the following suitable elaborations: extracting plans, prospects, profiles and sections at different heights and in appropriate parts of the model; turning the discreet model (cloud points) into a continuous one; projecting the photographic image on the mesh model in order to acquire material and pathology's information. The high precision of the analyses carried out has been the basis to undertake the subsequent critical researches in order to recognize potential modular matrices by using the ancient unit of measure (roman foot); to interpret the geometry of some complex rooms such as the Calidarium, presenting an octagonal plan covered by a dome vault; to formulate hypothesis about historical stratification, rui- nes and modifications occurred throughout the centuries. Figure 2. Southern view of the Thermal complex Figure 1. Western view of the Thermal complex