Laser Scanner and Architectural Accuracy Text

In last years laser scanning have increased its application in different fields: from geological to architectural and archaeological survey, from real time monitoring to rapid prototyping. Respect to architecture and archaeology, but more generally to Cultural Heritage, laser scanning technology is becoming more popular as can be proved in the latest works: big amount of data, accuracy, operability are some of its main characteristics that are fundamental in digital (numerical) models representations. If advantages are clear, it’s possible to attend to a continuous and increasing demand for better performances that correspond to the necessity to update and to implement continuously instruments respect to growing applications. In this paper authors want to point out some technical considerations on these new instruments, on their improved and improvable performances respect to their application fields. As was asserted in many experiences, laser scanner specifications, given by L.S. producers, concern to laboratory parameters so they do not correspond with practice conditions of acquisitions, which are usually more complicated and less controlled than laboratory test. Considering other well-known literatures (e.g. Boehler et al., 2005) and knowing that accuracy varies from instrument to instrument on the base of their individual calibration, some tests were done to probe not only the standard parameters of laser scanner (accuracy, density, times..) but even some features that are usually dictate from “real conditions” of acquisition: acquiring time, accuracy of measurement at different distances, feedback of different materials in the same scan, capabilities in describing simple an complex geometric properties (such as a façade of a church or a detail of a moulding), operability of different acquiring system. Moreover it was estimated the possibilities of integration between laser scanners and photogrammetry (i.e. multi-sensor integrations) and topography. As test area were chosen a part of the historical building of the university and the columned façade of a close church. We carried out all these tests using different producers laser scanners, but even different type of the same firm in order to identify the most suitable instruments for an architectural survey.