The advantages of digital technology
One of Factum Arte´s core strengths is and obsessive interest in the qualities that make things specifically what they are. This has led to the purchase of existing 3D scanning systems and the development of new ones. While a great deal of attention has been paid to the hardware, equal attention has been focused on the development of software. Perhaps the most significant development made by Factum Arte is the use of a laser scanning system that requires no meshing. The commercially available systems all require meshing and therefore the close correspondence between the exact surface and the 3D file is reduced.
Laser Scanning
Factum Arte analyses each project and designs the system that will produce the best digital recording in 2 and 3 dimensions.
Factum Arte´s Seti scanner, built in collaboration with 3D Scanners UK uses a class 3 A red light laser similar to that used in bar-code readers. The laser emits no ultra-violet light nor does it generate any discernable heat. During scanning the laser is in contact with any point on the object for only a fraction of a second. Due to the sensitivity towards the use of new technology in heritage, Factum Arte has produced an in-house conservation report onto the risks of Laser Scanning and has carried out tests that demonstrate the laser used is incapable of producing visible change to the surface being recorded.
The most important aspect of this scanning system is that the points in a 3D space are placed onto a regular grid. Each point on the grid is 100 microns apart while the variation in the Z axis no more than 5 microns. The system was developed specifically to record polychromed high relief carving in the Valley of the Kings but it has subsequently been wied on many projects from recording the surface of a C10th vellum manuscript in th Biblioteca Nacional, Madrid to detailed portraits of popcorn for the artist Marc Quinn.
This scanning system was built by Rapier Engineering in the UK and was used successfully during the six-week trial season in the tomb of Seti I. Following this period of work, further modifications were made, including the development of new software. Since its original design various mechanical modifications have been made resulting in a second generation of this scanner, the Yabba scanner.
Factum Arte uses different systems and approached to meet different requirements. While the Seti Laser Scanner has been designed for the accurate recording of high relief surfaces that require accurate surface detail it is not suited for the recording of large scale freestanding sculptures or relief surfaces with deep undercuts. The Kreon Zaphyr scanner is mounted onto a 7 axis SimCore arm. In practice the resolution is significantly lower than that achieved with the Seti or Yabba scanners (in practice we can achieve a resolution of between 300 and 400 microns working with this system) but it has a practical use as part of a scanning protocol.
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 Kreon Zephyr laser head scanning in Harvard Art museum
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The Model Maker from 3Dscanners UK was used to scan the Dama de Elche
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Factum Arte spent several years researching into laser scannng systems that could record fully 3D shapes. We finally chose the Kreon Zaphyr mounted onto a 7 axis SimCore arm. In practice we can achive a resoultion of between 300 and 400 microns working with this system. One of the main reasons it was selected was that the French company have actively responded to our specific demands and are prepared to modify the system to meet the specific needs of documenting cultural heritage.
White light Scanning
Another system used by Factum Arte is the white light scanning system produced by NUB3D in Barcelona. SIDIO uses the conjunction of optical technology, 3D topometry and digital image processing to extract 3D coordinates from an object surface. This technique is known as structured white light triangulation and the light is the only element used throughout the measuring process.
Three-dimensional information is acquired by analysing the deformation caused when projected lines are projected onto the surface of an object. Series of images are captured by an integrated camera in the measuring head. This process is performed in a few seconds.
From these images SIDIO integrated technology calculates a co-ordinated x,y,z point cloud relating to the surface of the object.
Following extensive research Factum selected this system as it has been developed by a small company who are very responsive to our requirements and work alongside Factum Arte to perfect the application of this system for conservation uses.
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Nub 3D White light system was used for Seneca and Nero Digitalization
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Nub 3D White light scanning was used for this Marc Quinn´s sculpture and some others like the facsimile of Eduardo Barron or the collosals lion from Nimrud |
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Software developments
Artifacts in the data are unavoidable when scanning to such a high resolution. Writing new software to correct these artifacts without affecting the data is requires specialised skills but is an essential part of Factum Arte's work.
The 'factory roofing' effect is the most visible and problematic scanner artifact caused by slight misalignment in each pass of the scanning head resulting in a tiny ridge between passes. This is not significant when viewing the image on screen but is instantly visible once the data has been cut..
The eye is very sensitive to regular artifacts that occur in an organic surface and unless removed these lines would destroy the realistic effect of the facsimile. To correct this fault a 3D retouching software was written. Software has also been written to orientate the complete tiles to perfect alignment, ensuring a seamless fit in both horizontal and vertical axes. Other artifacts such as spikes, holes in the data, vibrations and noise can also be removed using this program.
Digital Restoration
Another advantage of digital media is the potential to manipulate the data. It is possible to digitally restore the object both by working with specialists to modify the data and by scanning fragments that have been dispersed in museum and private collections. This way the data can be merged to produce a digitally restored facsimile of a damaged original. The precise protocol for this has yet to be established although the current practice is to insert these fragments while clearly marking the join in a discreet but visible way.
 
reconstruction from digital data
In the facsimile of the tomb of Seti I restoration of certain features can be carried out by reproducing equivalent features from elsewhere in the tomb. Working with the world expert on the tomb Erik Hornung, it would be possible to restore the entire tomb by scanning all the fragments that were removed and are now in Museums and private collections around the world. Once these are re-integrated the integrity both of the tomb and the text on the walls would be partially restored. It would then be possible to work with different experts to suggest how the tomb may have looked when it was uncovered in 1817, or how it may have looked in the days of Seti I.
For a more detailed explanation about this subject click on the Publications bar at the top of the page where you can read in-depth reports on some of the publications produced by Factum Arte
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