Lucida is a 3D laser scanner custom built by Factum Arte with financial and logistical support from Factum Foundation. Conceived and developed by artist and engineer Manuel Franquelo, this system is the result of fourteen years of research into the high-resolution recording of the surface of paintings and relief objects.

The digitization of the relief surface of a work of art is a relatively new field of research: it can be used to both study and monitor the surface of an object or to re-materialise it in diverse forms, ranging from projections to the construction of exact facsimiles. The validity of this type of recording is dependent on the quality of the data gathered and its correspondence to the original surface.

From the first photographic 3D scanner in the 1920’s recording has focused on capturing the shape of an object and it is only very recently that the technology has been available to record surface data accurately. Texture is essential for research and documentation purposes. Accurate recording of the relief and texture of a work of art (usually in combination with colour and multi-spectral recording) is leading to new insights and an intimate knowledge about the history of the objects and why they look the way they do.

Factum Arte has extensive experience in employing digital technology to record cultural heritage sites and objects in diverse locations around the world - from the Valley of the Kings in Egypt to the Musée du Louvre in Paris. Due to the specific requirements for each project, Factum Arte has adapted and improved the systems available on the market to achieve higher standards. After years of struggling with hardware and software not designed to be applied to works of art, Manuel Franquelo and Adam Lowe decided to design and build a bespoke 3D laser scanning system: Lucida, the brainchild of Manuel Franquelo, has been assembled using specifically designed and manufactured components as well as readily available off-the-shelf parts. Lucida’s specially written software contains features for editing, merging and blending,all of which have been programmed in-house.

Lucida has been developed and tested in many locations to obtain contact-free high-resolution 3D data from the surface of paintings and objects with low relief. It is a system fitted with two cameras and one laser that records depth information that can be handled as both an image and a 3D file. The laser scanner records an object by projecting a thin strip of red light onto the surface of the artwork. As the strip moves over the surface it is recorded by two cameras positioned at an angle of 45 degrees either side of the laser. The distortions of the line produced by the relief are recorded and stored as raw black and white video which can be rendered to produce an image or converted into 3D information. The scanner moves parallel to the surface plane of the object, controlled by linear guides (see images) and is always at a distance from the surface.

Other 3D recording systems also have severe difficulties when it comes to recording objects with significant contrast and/or reflective surfaces like gloss varnish or gold.

Most commercially available 3D scanners produce noisy data from reflective and dark surfaces which renders their use meaningless for recording and monitoring the surface of paintings. The relationship between noise and information is especially critical when the information that is being recorded is subtle. For the recording technology to be meaningful for cultural applications, it is essential that the correspondence between the surface and the data is as close as possible. Lucida has overcome the problem of contrast and reflection through innovative hardware and algorithms designed to reduce noise without altering the surface characteristics. Practical testing in leading museums like the National Gallery (London) or the Museo del Prado (Madrid), has demonstrated that Lucida can record accurate high-resolution data from the most challenging surfaces.

One of the features that makes Lucida unique is that it stores the 3D information in the form of raw tonal video. Storing data in raw video means that it will be possible for it to be re-processed at a higher resolution or with further developed technologies in the future. This is a radical innovation that reflects a deep understanding of the needs of the conservation community. Other scanning systems process the recorded data into a three-dimensional point cloud and mesh as it is being recorded. This is an irreversible abstraction that results in a permanent loss of information. Lucida stores raw video while at the same time generating a series of files: AVI (Video), RIS (3D), TIFF 32 bit and 16 bit (greyscale depthmap) and TIFF 8 bit(shaded rendering).

A second innovation is the use of increasingly powerful image-stitching software as an integral part of the process (Adobe Photoshop and/or PTGui). After the RIS file has been edited (to fill holes and remove noise) the shaded rendering is corrected using homography (projective geometry), stitched and then ‘switched’ for the 32 bit greyscale data that contains the depth information. This ‘edited’, ‘merged’ and ‘aligned’ file can be exported into software like Artcam (.stl or .obj) and used to re-materialise the 3D data as a physical form with the surface character of the original. It is by virtue of these steps that the recorded data can be processed and accessed without specialised 3D software that tend to be costly and require regular, often expensive, updates.

As the file is an image file it can be integrated with other image files to produce accurately aligned multi-layered browsers that can integrate infra-red, X-ray, colour and other types of information in conservators' reports, historical images and various forms of forensically accurate analysis. Multi-layered files are proving to be very helpful to researchers and conservators as they provide an accurate, objective and meaningful method for monitoring the condition of the artwork.

After many years of development the Factum Foundation, Manuel Franquelo and Factum Arte have been able to develop a 3D scanning system that is easy to understand, easy to use and easily transportable. The Lucida can be operated by anyone with a good understanding of image processing and only a basic training in 3D software.

Read the Lucida 3D Scanner's training guides in English:
Training guide I: Assembly instructions
Training guide II: Operator's manual
Training guide III: Processing applications
Training guide IV: Appendix
Edition on Selected projects I

Read the Arabic edition here.

The development phase is coming to an end and the Factum Foundation is now ready to initiate a transfer of technologies and skills to the museums and institutions around the world. Hence, it will contribute to the conservation, the documentation and diffusion of the Artistic and Cultural Heritage. The Lucida 3D scanner has already been used to record artworks in the Museo del Prado in Madrid, The National Gallery in London, the Vatican Museums, the Pinacoteca di Brera in Milan, the Courtauld Institute of London, the Ashmolean Museum Oxford, and many others. The quality of this system’s capabilities has been clearly demonstrated and new scanners are now being milled and assembled in Factum Arte’s workshops.

CREDITS

Manuel Franquelo: Concept and design of electronics, mechanics, optics, and software.

Fabricated and tested in Factum Arte by Carlos Bayod, Jorge Cano, Dwight Perry, Carlos Alonso, Nicolás Díez, Manuel Franquelo Jr, Guendalina Damone, Enrique Esteban and Aliaa Ismail under the supervision of Manuel Franquelo.