Integrazione di Tecniche di Fotogrammetria e Laser Scanning per la modellazione 3D della carena di una imbarcazione

In this paper we describe an experimental application for the integration and comparison of two survey methodologies, digital photogrammetry and terrestrial laser scanning, for reverse engineering applications in the field of nautical science and more general in Naval Engineering. The two methodologies are able to provide independently all the key elements needed to model the surveyed object,but their integration certainly ensures the best results in terms of reliability and completeness. The experiment, carried out on the hull of a twelve meter long sailboat, has given important hints about the features of the two surveying methodologies and of the equipment that has been used and about the specific problems related to hull evaluation. It also has shown that laser scanning and photogrammetric techniques integration can be useful for solving problems that appear when using only one of them. The technique used in this test has been shown to be appropriate for the geometric control of hulls to compare the actual shape to the original design, and to check that the required accuracy constraints are satisfied. The photogrammetric survey was carried out by means of a Nikon D100 digital camera equipped with a 35mm lens, whereas the scanning was performed with the laser scanner Optech ILRIS 36D, a device based on the Time of Flight (TOF) method which allows for long range and high speed scanning, also exploitable for surveying objects of large dimension as the sailboat used for the test, despite limitations characteristic of TOF laser instruments.