Applicazioni del Laser Scanner terrestre a temi geologico-tecnici

Laser scanner is an electronic instrument capable to survey the three-dimensional geometry of an object through a laser pulse measuring the distance between the laser head and the objects surface. Accuracy, acquisition time and range varies between several commercial products. Short range (up to 50-70 m) scanners can survey in few minutes at high resolution (ca. ± 2 mm), while long range scanners (up to 2000 m) can provide a decimetric accuracy and need more acquisition time. Laser scanner has the advantage that doesn’t need passive corner reflector on the object but on the other hand the measure accuracy could be dependent on the surface characteristics (material, dielectric constant, etc.). The laser scanner output is a three-dimensional cloud of points colored by reflectance values. Both the cloud of point and the derived mesh model can be textured using a external digital images; the final result is photorealistic model of the object completely measurable. Terrestrial laser scanner technology (hardware and software) is in continues developing and several application are related to the geological survey field of application. In particular laser scanner was applied for geo-mechanical analyses, rock fall monitoring, tunnel and cave survey, glacier monitoring. Further development are planned to simplified the usage and analyses of laser data for geologist trough user friendly software tool

A Moving 3D Laser Scanner for Automated Underbridge Inspection

Recent researches have proven that the underbridge geometry can be reconstructed by mounting a 3D laser scanner on a motorized cart travelling on a walkway located under the bridge. The walkway is moved by a truck and the accuracy of the bridge model depends on the accuracy of the trajectory of the scanning head with respect to a fixed reference system. In this paper, we describe a vision-based measurement system that can be used to identify the relative motion of the cart that moves the 3D laser scanner with respect to the walkway. The orientation of the walkway with respect to the bridge is determined using inclinometers and a camera that detect the position of a laser spot, while the position of the truck with respect to the bridge is measured using a conventional odometer. The accuracy of the proposed system was initially evaluated by numerical simulations and successively verified by experiments in laboratory conditions. The complete system has then been tested by comparing the geometry of buildings reconstructed using the proposed system with the geometry obtained with a static scan. Results showed that the error is less than 6 mm; given the satisfying quality of the point clouds obtained, it is also possible to detect small defects on the surface

Innovative and efficient data census on a cloud based digital twin provided by mobile mapping.

The article introduces the use of modern indoor mobile mapping systems (iMMS) equipped with a high resolution photographic camera, for the realization of asset acquisition campaigns of large building sites and for the generation of Digital Twins. The mapping project of a large part of the social housing real estate of the Municipality of Milan is taken as an example. The technical specifications and management methods of the 3D measurement and photographic acquisition processes in the field and the processing workflow, quality testing/certification and way to share on the cloud the Digital Twins are described

Laser scanner per il disaster management in ingegneria

L'articolo descrive le scelte metodologiche, gli strumenti e le fasi del rilievo di una imponente struttura reticolare di copertura che ha subito un collasso. In casi di eventi di tale importanza risulta di estrema necessità il rilevamento e la documentazione dimensionalmente certa delle geometrie della struttura e degli elementi strutturali che la compongono, sia per fini legali, di pianificazione degli interventi di recupero e per ragioni assicurativ

Laser scanner per il disaster management in ingegneria

L'articolo descrive le scelte metodologiche, gli strumenti e le fasi del rilievo di una imponente struttura reticolare di copertura che ha subito un collasso. In casi di eventi di tale importanza risulta di estrema necessità il rilevamento e la documentazione dimensionalmente certa delle geometrie della struttura e degli elementi strutturali che la compongono, sia per fini legali, di pianificazione degli interventi di recupero e per ragioni assicurativ

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

International audienceWe 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 surve