By Rand Eppich and Francesca Piqué

In a small computer lab at the Getty Conservation Institute, Irene Sen and a fellow conservator are discussing the GCI's work on The Last Judgment mosaic in Prague. Located on the exterior of St. Vitus Cathedral, the 14th-century glass mosaic has suffered from pollution and the extremes of the climate in the Czech Republic. Sen, a GCI research fellow, sits down at a computer keyboard and opens an electronic file that contains all the graphic information concerning the mosaic. An image of the multicolored mosaic appears on the monitor, followed by an overlay of graphic and written notes on the mosaic's condition. The fine details are not apparent at first, so Sen enlarges an area of the mosaic near the representation of the central figure of Christ in judgment. The discussion turns to previous conservation interventions. Sen moves the mouse over a button that controls layered information about the mosaic. After a few clicks, most of the information disappears, except for red lines that cross the mosaic. Sen explains that these lines show where the mosaic was cut to be detached in the late 19th century. She highlights the area and selects "print"; soon she has a color print of the part of the mosaic under discussion.

An example of graphic representation of some of the conservation information recorded for the central panel of The Last Judgment mosaic on the Golden Gate of St. Vitus Cathedral in Prague Castle. At the end of the 19th century, the mosaic was cut into 273 sections and removed from the cathedral facade. The drawing indicates the edges of the detached sections, as well as areas of original and new tesserae and traces of the original gold gilding. The mosaic's conservation is a collaboration between the Office of the President of the Czech Republic and the GCI.

As in many of the GCI's recent field projects, The Last Judgment mosaic project's graphic documentation is being carried out on site in a way that can be easily transferred to digital form. Photographic and computer technology, often in conjunction with traditional methods of documentation, now provide the basic tools for the recording and manipulation of data concerning the original technique, conservation history, and conservation intervention of an object, mural, mosaic, or site, as well as its existing state of conservation.

The center of the GCI's computer documentation work is the digital lab, which houses imaging equipment and computers loaded with some of the latest software programs. Created over three years ago by the Institute's Conservation group to promote digital documentation, the digital lab has three objectives: support for documentation in field campaigns, training, and research.

When a site—which might contain mosaics, murals, and architectural elements—or an art object is selected for conservation, the first task of the conservation team is to carry out an in-depth examination. This includes the graphic recording of the site or object's condition. By studying all aspects of a site or object, one acquires an accurate understanding of its present state (including the nature and extent of deterioration), previous interventions, the original technique, and the effects of past damage.

Condition recording is an essential component of a conservation project. It provides the basis of knowledge for project management, investigation, and the development of a conservation plan. Information gained from condition recording supports condition assessment, enables cost analysis in project management, and guides the use of resources. It also provides information for fund-raising, the development of partnerships, and publishing.

In addition, condition recording helps identify needs and priorities for investigation and treatment planning. Conservators gain significant understanding of an object or site while recording its features. The type, extent, and location of damage are crucial to understanding the processes and causes of deterioration; they also will indicate the need for additional investigation. Furthermore, in-depth examination reveals the effectiveness of methods and materials used in previous interventions.

During treatment, graphic condition recording is used as a reference and as a basis for annotation. It remains a key document for the future, providing a foundation for evaluating changes in the conserved object or site.

In the past, all this information was collected in great detail, in notebooks, on paper, and on acetate. It was, however, tedious and time consuming to modify information in this form and to duplicate, disseminate, manage, and store the data. The use of computer technology to record and manipulate the documentation allows greater ease and flexibility in working with the variety and amount of information required and collected in a conservation project.

The conservation team at work on digital documentation of 16th-century wall paintings by Italian artist Filippo Paladini, located in the Paladini Chapel of the Grandmaster's Palace in Malta. Graphic information was collected traditionally and transferred to digital form directly in front of the paintings. This reduces mistakes that occur when data transcription is carried out away from a site. The documentation is part of a collaboration between the Valletta Rehabilitation Project, the Courtauld Institute of Art, and the GCI. Photo: Ray Bondin.

An example of this was the recent condition assessment of the 16th-century retablo in Yanhuitlán in Oaxaca, Mexico (see The Retablo of Yanhuitlán). The retablo, a wooden altarpiece approximately 19 meters in height, is located in the apse of the Church of Santo Domingo. Considered one of the country's most important examples of colonial art, it has suffered damage from water, insects, and seismic activity. In the early stages of the project, the conservators decided that as part of the assessment phase, the condition recording would be done in digital form.

During a documentation campaign, Irene Sen installed a desktop computer—with Spanish versions of AutoCAD and Adobe PhotoShop—in the dimly lit church. Balancing on scaffolding, the documentation team first recorded the condition information (i.e., cracks, paint loss, flaking, insect damage) in the traditional manner by marking on acetate sheets over photographs of sections of the retablo. Conditions were then redrawn in the computer over onscreen digital photographs of the altarpiece.

The electronic files created by Sen consist of images and graphic notations containing conservation information and text. These sets of information are overlaid to create a combined visual and written record of the problems of the retablo—a record that can guide the development of a conservation strategy.

The use of digital technology is not always convenient in the field. In Yanhuitlán, obstacles to the computer's use included an irregular power supply, copious amounts of dust, and the need to halt work during church services. But enduring these difficulties was worth it. Using the computer in the field as a tool in conservation assessment enabled the project team to create a detailed and comprehensive digital record of the state of the retablo, eliminating any possible mistakes that could have occurred during transcription of information, had it been done far away from the altarpiece.

As part of the retablo's condition recording, Sen trained Javier Salazar of Mexico's Instituto Nacional de Antropología e Historia (INAH) in the use of this technology. In two weeks, despite interruptions, Sen and Salazar made a good start on collecting information in digital form. After Sen's return to the GCI, Salazar remained on site and completed the condition recording.

Conservators at the GCI who have used computer-aided tools find that digital documentation records offer all the advantages of digital formats, including infinite reproducibility. They can be edited, duplicated, stored, shared, and even e-mailed. This can all be done more easily and cost-effectively than if the records were in paper form. In addition, data analysis is greatly improved by the use of computer-based technologies, which offer capabilities impossible to achieve in exclusively manual systems.

GCI project specialist Francesca Piqué—at the site of Horvat Minnim in Israel—graphically recording conditions onto transparent sheets positioned over photographs of the mosaic. The sheets were then scanned to create layers of information, in digital form. The recording, part of the assessment of eighth-century mosaics in the Umayyad Palace, is a component of a collaborative project between the Israel Antiquities Authority and the GCI. Photo: Frank Long.

On the Mediterranean coast of Israel, as part of a mosaics project undertaken by the GCI and the Israel Antiquities Authority, digital condition recording is being used at the ancient site of Caesarea to track changes in the condition of five mosaics. The mosaics, which are vulnerable to the damaging effects of rain, wind, salt, and heavy tourist traffic, are being used to test and evaluate four different protective measures. As part of the test, conservators examine the mosaics monthly and update the condition record for each mosaic. This procedure is easily accomplished when the data are in digital form. Furthermore, because the computerized graphic data are quantifiable, the digitized condition record will show more precisely the comparative rates of deterioration and the efficacy of the protective measures.

Because technology is developing so rapidly, the GCI digital lab continues to review new and existing technologies and their possible applications to conservation. Determining the best possible method for conservators to record in graphic form is another element of the lab's research. For example, the most efficient way to obtain a digital document on site is to record on the computer directly. However, when it is not practical for laptop computers to be brought into the field, the digital lab has developed protocols for traditional recording that allow easy transfer of data and images into electronic form.

By studying new software, hardware, and techniques, and by conducting experiments, the digital lab seeks to improve the efficiency of conservators by providing information on the benefits and potential pitfalls of selected tools.

Last May, Evin Erder, a GCI research fellow, used a total station (a survey instrument that measures distances and angles electronically) to gather data on the Tel Dan gateway, a 1800 B.C.E. mud-brick arch structure in northern Israel. It is among the earliest known examples of an arched structure, and although protected by a shelter, it continues to deteriorate. Using the instrument, Erder was able to painstakingly record cracks and the deformation of the facade in three dimensions. These data have been combined with a photogrammetric computer model to provide a complete picture of the gate. During future monitoring, the information can help determine if the cracks are changing and if material is being lost from the structure. The innovative use of this methodology in the Tel Dan gateway project is an effort to establish more effective techniques for recording three-dimensional data on heritage sites. These data provide a complete picture of the structure that would otherwise be impossible if only plans, sections, and elevations were used. The data can also be used to help recreate how the arch might have appeared when first constructed.

GCI research fellow Evin Erder using a total station to record three-dimensional information on the location of cracks and other conditions of the 18th-century B.C.E. mud-brick gateway at the site of Tel Dan in Israel. The data collected in this precise way can be used to monitor changes in the gate. The documentation was part of a project of the Israel Antiquities Authority and the GCI. Photo: Rand Eppich.

Choices about how to apply digital technology to conservation documentation should be guided by the specific needs and purposes of a project. Depending upon the resources available and the characteristics of the site environment, a variety of more or less sophisticated tools—ranging from traditional pen and paper, through laptops in the field, to digital photogrammetry—can be employed. In every instance, planning prior to field campaigns is essential to best gather the information for effective use. Because the bulk of documentation information on GCI projects is ultimately transformed into digital data, a close working relationship has developed between field conservators and computer specialists on staff. This collaboration has greatly enhanced the development and improvement of methods for graphic recording.

The integration of digital tools into the conservation documentation process is still in its early stages. Nevertheless, it holds the promise of vastly increasing the body of information easily available to conservation teams in the field, in the lab, and for coordination and comparison between similar projects, thereby facilitating the effectiveness of their work.

Rand Eppich is a research fellow and Francesca Piqué is a project specialist in the GCI's Conservation group.

Members of the GCI Staff Involved with the Digital Lab