Technical developments

Seti laser scanner (version 2) recording in the Tomb of Tutankhamun, May 2009

Seti laser scanner (version 3), recording the standard scanning test, August 2009. The development of this scanner has been financed by the Foundation for Digital Technology in Conservation and made by Metris, Belgium for specifications supplied by Factum Arte. It records slightly faster that the previous laser scanner and at the same resolution but its main advantage is that it integrates Metris software enabling it to record both dark and light colours at the same time. During tests with the Standard Scanning test it also successfully records the black glossy areas. Development work will be finished on the 28th November. Once it has been fully tested it will go into production and be used to record both the tombs in the valler of the Kings and Caravaggio's paintings.

Nub 3D white light scanner (modified to work in the tombs in the Valley of the Kings)
recording the standard scanning test, October 2009. Nub 3 D have been working to perfect this scanner for use in conservation. One challenge was to get rid of the 2 'marker' projectors that generate significant heat and the next was to mount it onto a linear guide system. Both of these have been achieved and successful scanning tests have been done at 75 microns.

The files generated with the NUB 3 D scanner are small scale and very high resolution. In order to stitch these files together and prepare them to be routed in 3D new software has been developed. Software of this kind is essential to ensure there is no loss of resolution between the recording and the output in three dimensions.

Standard 3D scanning test. This test has been designed in direct response to Factum Arte's needs when recording the surface of important works of art. The left third is an area of relief carving, the central section is a densely cracked surface and the right hand third is a mix of relief and colour. Over the central and right side are three circles of midtone grey, dark grey and black. Overlappong these are 3 circles of varnish; matte, satin and gloss. Scanning glossy black and matt white at the same time represents a serious challenge for laser scanners and produces artifacts in White light scanners. This test has been satisfactorily scanner with both the new scanners in development.

Standard 3D scanning test (detail).

Technical specifications for work carried out inTutankhamun

During the first 3 months recording in the tomb of Tutankhamun the following equipment was used:

Equipment	Working Resolution
“SETI” low intensity red light laser scanner (Reversa)	100 microns
NUB 3D white light 3D scanner	200 microns: Sarcophagus 700 microns: Walls
Phase One H25 digital back on a Hasselblad MF camera Canon EOS 5D with 180mm lens and integrated lighting system	1:1 at 900 dpi

Factum Arte is continuously improving its techniques and expects to introduce similar but updated equipment as the project progresses.

Factum Arte - 3D Scanning Systems

Factum Arte started recording with two 3D scanning Systems. The Reversa Scanning System and the NUB 3D Triple System. Details are provided below about each system. During the next recording season we will also be using a lower resolution scanning system (Leica Lidar) to record the ceilings and overall dimensions of each room. We will also be recording each room photographically and will merge all the 3D and colour data together in Madrid.

Since the test scanning in 2001 we have still been unable to locate a scanning system that can match the quality of the Reversa scanner. As a result we are now in dialogue with Metris to see if we can put this type of scanning head back into production with improved cameras and lasers. This research is almost complete (see above).

Reversa Scanner System

A Reversa laser scanning head made by 3D Scanners mounted onto a lightweight aluminium structure. The most important aspect of the Reversa 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. There are 100,000,000 independently recorded Z axis (height) measurements per square meter. The Reversa laser scanner can record 1.5 to 2 sq meters of relief surface at a resolution of 100 microns per 8-hour period. We are currently developing a new digital scanning system that can record 5sq meters per day. All scanning and photographic work is non-contact and nothing is fixed to the walls during any part of the recording.

The system was developed specifically to record polychrome high relief carving in the Valley of the Kings but it has subsequently been used on many projects from recording the surface of a C10th vellum manuscript in the Biblioteca Nacional, Madrid to Assyrian reliefs if the British Museum, London.

The system has been used in: The Tomb of SETI I, Valley of the Kings, Luxor Egypt (2002); The British Museum, London, England (2004-5); Pergamon Museum Berlin, Germany (2004); Museé du Louvre, Paris, France (2006); Biblioteca Nacional, Madrid, España (2005); Museo Arquelogico Nacional, Madrid, España (2004).

A conservation report on the use of Laser Scanners in conservation was supplied to Dr Hisham Shokeir at the National Institute of Laser Enhanced Sciences on 15 Jan. 2009. The report demonstrates that the Laser used in the Reversa scanning head is incapable of causing any visible damage to any of the surfaces in the tomb of Seti I.

Lightweight Modular Structure for Reversa, Nub3D and photographic recording systems

Modular lightweight aluminum structure specifically designed for use in the tomb of Seti I. This Structure is designed by Factum Arte and built by IPREM S.L. Each system consists of 3 modules that fix together to form a rigid tower. Each module has two vertical tracks that facilitate accurate positioning of the linear guide frame. The modules can be stacked up to 3 meters high. The external structure will come with a calibration attachment made out of aluminum. The dimension for each module is 100x100x50 cm.

X, Y, Z Linear Guides

This frame with X, Y and Z axis linear guides is fixed to the vertical tracks of the external structure. The reversa sensor is mounted onto the Z axis. The accurate linear guides are controlled by a Triomotion series 1 CNC.

Rack computer

This computer has been installed with RISCAN 3.3. software to operate the scanner. The software runs on Windows NT. External hard drives and an internal CD writer are used to backup the data as it is recorded. The computer system comes with a flattron LG 19 inch monitor, a PS2 connection mouse and a PS2 connection keyboard.

Reversa Sensor Model 25

Low power laser scanning system consist on 2 analogue signal CCDs and a CLASS 2 (old 3A CLASS) red laser stripe projector. This sensor will be mounted in the linear guide frame. The scanning head is packed in a metal case along with the sensor mount, sensor connection cable, Serial Cable, SURFA PC ISA Card (specialized image processing card) and calibration plate.

Reversa scanner technical specifications
Model Reversa 25
Measuring range (z)	25 mm
Stripe length	15 mm
Stand off at the top of the range(Z)	100 mm
Resolution on Z axis	5 microns
Working measuring spacing	100 microns
Dimensions:	20x8x8 cm
Weight	600 gr

The Foundation for Digital Technology in Conservation and Factum Arte will make a significant transfer of technology to the SCA during the realisation of this project. One Reversa Scanning system will be given to the Supreme Council of Antiquities to be operated by graduates from the National Institute of Laser Enhances Sciences at Cairo University. As the funding is available more systems will be presented to the SCA so that scanning the tombs can continue uninterrupted and assist in the preservation of the tombs in the Valley of the Kings.

NUB 3D SIDIO Triple scanner

Factum Arte uses a white light scanning system produced by NUB3D in Barcelona to record complex 3 dimensional forms, niches, the corners of pillars and doors.

The Triple Scanner uses a 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 light is the only element used throughout the measuring process.

Three-dimensional information is acquired by analysing the deformation caused when lines are projected onto the surface of an object the resulting series of images is captured by an integrated camera in the measuring head. From these images SIDIO integrated technology calculates a co-ordinated x,y,z point cloud relating to the surface of the object.

Triple is a white light scanning system developed by the Spanish company Nub3D S.L.

This system has been used in: The British Museum. London, England (2006); Museo Tiflologico, Madrid (2006); Museé du Louvre, Paris, France (2007); Museo Nacional del Prado, Madrid, España (2007);

The system is mounted on 3 tripods and operated by Computer. The SIDIO STANDARD measuring senor is mounted on one tripod. There are two tripod mounted markers. Both markers use U4-232 projectors with a Polarizing lens. Computer is a Processor Pentium IV 3,0 GHz with an ASUS P4P800-SE motherboard. The operating system is Windows 2000 Profesional SP4. There is also a dongle protected Triple 1.1 operating system. The computer uses a GF ASUS V9570TD Graphic card, SATA BARRACUDA 7200 120GB hard disk, Keyboard and 17 inch monitor. 4 PCI graphic cards for the measuring sensor and markers send information between the components are internally fitted into the computer.

The 3D software used with this system is Polyworks/Modeler.

Nub3D triple system