Laser Scanning and close range photogrammetry: Towards a single measuring tool dedicated to architecture and archaeology

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We present here the first steps towards the development of a tool for architectural and patrimonial survey which combines the laserscanning techniques, close range photogrammetry and a fine analysis closer to the studied field, here architecture and archaeology.The present work is the result of a join cooperation between, INN.TEC.srl, an Italian Innovation Technology Consortium, with aCenter of Competence (Topotek) specialized in geomatic problems and in particular in the treatment of cloud of 3D points comingfrom Laser scanner, a French CNRS laboratory working on close range photogrammetry in the context of architecture andarchaeology and a laboratory from the university of Rome III, specialized in the representation of architecture.We present a knowledge based survey tool which combines mixed means of Laser Scanner and photogrammetry measurement.The statement is articulated in three phases:• Laser scanner allows to model objects in 3D with a density of measurements that cannot be acquired within a reasonabletime frame with traditional technologies. The programme used for laser data management creates a triangular 3D model(mesh) from the range information and maps 2D information on the 3D model to create the final result.Generally laser scanning requires to view the surveyed object from several viewpoints to resolve shadows and occlusionsbut displacement of the laser sensor is not always easy to achieve on site• We developed a similar approach in photogrammetry which, using some photographs taken without too many constraints,can supplement the occlusions or lacks from the laser measurements. A survey based on an approximate geometry of theobject and autocorrelation makes it possible to obtain automatically an irregular mesh with appropriate texture. Theorientation phase uses the data provided by the scanner to orient the photogrammetric measurement in the same set of axes.• The last phase involves the use of an expert system based on a knowledge representation of the object measured in order torebuild an architectural or archaeological object while being based to the taken measures and an elaborate ideal model incollaboration with the architects or archaeologists.The work presented here is based on an experimental study of an Etruscan amphora found on the Grand Ribaud F wreck, in HyËres,France, and studied by Dr. Luc Long, Cultural Heritage Curator, DRASSM, Marseilles, France. The survey took place at theUniversity of Rome III in the laboratory of architectural representation directed by Prof. Diego Maestri. The laser scanning wasmade with the Callidus sensor gracefully lent by the company Geosystem group, Roma.After this debugging phase on a simple object as an amphora, we project to extend this method for architectural survey