STEINBICHLER T-SCAN 2
Metropolitan Museum of Art, New York
Consejería de Cultura de la Junta de Andalucía
In early 1904, the Dukes of Medina Sidonia, then proprietors of the Vélez Blanco Castle, decided to sell the small amount of furniture still left in the castle, and in May of that same year they even sold off the building’s most precious gem, i.e. the Renaissance inner courtyard with its magnificent reliefs carved from solid white Macael marble, for 80,000 Pesetas to a French dealer named J. Goldberg. Stone by stone, the courtyard was carted away on pushcarts to the Cartagena Port, and shipped from there to Marseilles. In 1913 the courtyard was acquired by George Blumenthal, who, after his death, left it to the Metropolitan Museum of Art in New York, where it remains set up today as one of the museum’s main attractions.
The Consejería de Cultura de la Junta de Andalucía, i.e. the Council for Cultural Affairs for the Andalusia Region, is currently working on a project to recover the historic memory of the region through extensive restoration measures, with special emphasis on the Renaissance inner courtyard. The financing for this project is also provided by the Council for Cultural Affairs for the Andalusia Region.
RESTORATION WITH 3D SCANNING
New scanning procedures make it possible to create replicas of objects of art without the need for "touching" them - it is of tantamount importance to avoid damaging these objects. Traditionally, resins or silicones were used to create casting moulds from the objects of art – a process fraught with risk since parts of the object might easily remain stuck to the silicone or resin of the mould.
The Metropolitan Museum of Art in New York requested the Council for Cultural Affairs for the Andalusia Region to copy the Renaissance inner courtyard by using one of the new 3D scanning procedures to avoid damaging this precious object of art. As a result, it was decided to digitalize the inner courtyard (17x12 m surface, 9 m height) by means of a handheld 3D laser scanner developed by the German company Steinbichler. Common 3D laser scanners react very sensitively to brightness and daylight, and there exists only a single scanner capable for use in environments with constantly changing lighting conditions: the T-SCAN model. These scanners which are best suited for this task are marketed in Spain and Portugal by DeltaCAD.
Digitalization of the marble elements of the inner courtyard by 3D laser scanner was scheduled for August 2008. The T-SCAN measuring system is extremely mobile and can be easily transported - thus, data capture on site can be carried out without any difficulty. This state-of-the-art 3D laser scanner capable of recording millions of dots in the scanned areas with an approx. 100-mm wide laser beam from a approx. 10 cm distance to the scanned surface. Owing to its highly ergonomic design, the handheld scanner can be operated very easily and intuitively.
FUNCTION PRINCIPLE OF THE T-SCAN LASER SCANNER
A visible laser beam (670 nm, laser class 2), which is linearily orientated by a polygon mirror, captures the surface of the object to be measured with high scanning frequency. Using the triangulation principle, the measurement distance is calculated from the position on the object surface where the incident laser light is reflected back to the receiving optics. The exact spatial position of the scanner in all 6 degrees of freedom (6D: three spatial coordinates and three tilting angles) is determined by an optical tracking system which identifies at least three of the 29 infrared markers that are positioned on the scanner. By moving the scanner, the object surface is completely captured. The measured 3D coordinates are displayed on the monitor in real-time. A pilot beam and LED´s on the back side of the scanner are used to guarantee the optimum distance during the scanner movement over the object surface.
The company commissioned with the scanning task, DeltaCAD, has extensive experience in 3D scanning, in just about every field imaginable: from formula-one race cars to moulds and dies, to figurines for the "Fallas" (a folk festival in Valencia), all the way to sculptures of the country’s most famous sculptors. The measured 3D data processed by the T-SCANplus measuring and evaluation software are the basis for generating a mathematical model of the object surface of superior quality. E.g., in the automotive industry, the data are used for a further processing in CAD programs or for the generation of corresponding milling programs.
The scanning work had been carried out on site in August 2008. Afterwards, the single scan data were merged to receive a complete surface description of a true-to-original, virtual copy of the inner courtyard. The data from the scans were then forwarded to the Escuela de Marmol (Andalusian marble school) in Fines/Spain, where a replica of the Renaissance inner courtyards will be reconstructed from Macael marble block by block. The costs for the digitalization by DeltaCAD and the marble works carried out by the Escuela da Mármol in Fines will be borne by the Consejería de Cultura, the Council for Cultural Affairs, via the Empresa Pública de Gestión de Programas Culturales, a publicly owned enterprise for the management of cultural programs.
DeltaCAD is a company with offices on Madrid, Barcelona, Bilbao and Portugal and has extensive experience in the fields of optical scanning and CAD/CAM. In addition to customer consulting, sales, and training, services also include design, reverse engineering, and 3D scanning. The 3D sensors from Steinbichler Optotechnik (COMET, T-SCAN) are exclusively marketed in Spain and Portugal by DeltaCAD.