Documenting scholarly work is straightforward - researchers use footnotes. But what do researchers do when the work isn't a written document, but a visual image?

King's College London's Hugh Denard argues that a three-dimensional reconstruction of an ancient theatre is as much an intellectual argument as a written paper, likewise based on research, excavations, and other scholarly work.

But, he asks, "How do you footnote a visual argument?"

A 3D visual is such a powerful representation of an idea that viewers tend to accept it at face value as "the" true reconstruction of a site, yet it could be based on weak evidence. How would the viewer know?

Lacking footnotes, the representation lacks "intellectual transparency", he says.

With computer visualisations becoming an increasingly important scholarly tool, King's College and a group of like-thinking organisations decided it was time to create a set of standards for documenting 3D images by annotating the data used to build the image and making it an integral part of the overall data file.

This information might appear as a pop-up window when a mouse passes over an image, an embedded file, or an attached document.

The standards and objectives for such documentation are called the London Charter.

"The charter has had an enormous impact. It makes 3D work susceptible to peer review," Denard says.

The Italian Ministry of Culture is among those that have adopted the charter as a serious element of research.

"If you want to do archaeology in Italy, you have to follow the charter," says Denard.

www.londoncharter.org/