Computer camera helps to reconstruct masterpiece

Art and technology have fused in a remarkable study of an unfinished Michelangelo masterpiece, his second or Florentine pieta. One of three pietas undertaken by the master of Italian high Renaissance art, it was thought to have been destined to grace the artist's own tomb, but for unexplained reasons he attacked it with a hammer before completion and he abandoned it.

The work, carved from a single block of marble and depicting Nicodemus supporting the figure of the dead Christ with the help of Mary Magdalene and the Virgin Mary, was actually rescued by one of Michelangelo's servants who gave the unfinished piece away before the artist could do it any more harm.

It was eventually repaired and finished by Tiberio Calcagni, an otherwise undistinguished sculptor according to art historian and Emeritus Professor, Jack Wasserman. Prof Wasserman has made a particular study of the Florentine pieta, and is a historian of Italian Renaissance art at Temple University, Philadelphia, Pennsylvania.

In June 1997, Prof Wasserman began an intensive study of the pieta using existing photographic and gamma ray investigations. Getting the data he needed, however, was not helped by having to work on the statue in its cramped surroundings at the Museum of the Opera del Duomo in Florence. He approached IBM and asked the company to assist in creating a digitised reconstruction of the statue using techniques known as virtual image technology. IBM agreed to collaborate, thus launching the most extensive study carried out on a work of art, Prof Wasserman believes.

The study involves using special camera equipment that can capture detailed images of the pieta. These images are then brought "alive" through the use of software which would convert the images to signals in computer memory for display on a screen.

IBM joined forces with a company called Visual Interface, using a specialised Virtuoso Shape Camera, a device which takes six pictures simultaneously from slightly differing positions so that a three-dimensional image can be captured.

About 1,000 such images of the 2.5-metre tall statue were taken by the team this spring and then converted into computer signals. The software allowed the statue to be viewed from any direction and examined in minute detail. Texture and colour information was also integrated using a colour camera mounted on top of the Virtuoso.

Once computerised, the pieta could be deconstructed into its essential elements for study. For example, the figure of Christ could be detached from the rest and its proportions studied. Damaged or repaired portions could be "removed", giving a view of what the original might have been like before being attacked by Michelangelo.

"Michelangelo had a tendency to carve his work so the viewer could see it as he walked in arclike trajectory from one side of the statue to the other," Prof Wasserman said.

"The ability to stand each figure of this pieta up straight without distorting the dimensions and proportions would provide valuable insight into the question of what Michelangelo's proportions were like, his general concept of proportions, how he meant the work to be viewed at his tomb site, and, perhaps, his intent in taking a hammer to it."

Only Christ's figure was finished by Michelangelo, but his left arm had been broken and repaired and the left leg is missing. Mary Magdalene's face is only roughly blocked out and the other faces were done by Calcagni.

Prof Wasserman hopes to use the technology to reconstruct a virtual leg for Christ using the existing marks on the statue, examine what was there before the work was damaged and finish the face of Mary Magdalene. The team will return to Florence in August to take extra images where "holes" had been discovered, gaps in the virtual pieta left after the initial camera shoot.

The plan is to place the virtual pieta on CD-Rom and include it in a book of essays on the sculpture edited by Prof Wasserman and published next year by Princeton University Press.

Having developed a unique body of software suited to three-dimensional image capture, IBM hopes to develop this technology for use in other applications such as digitising other artistic masterpieces or works of architecture.