I Image-based 3d Recording 3d Recording for Archaeological Fieldwork 2

n archaeology, measurement and documentation are both important, not only to record endangered archaeological sites, but also to record the excavation process itself. Annotation and precise documentation are important because evidence is actually destroyed during archaeological work. On most sites, archaeologists spend a large amount of time drawing plans, making notes, and taking photographs. Because of the publicity that accompanied some recent archaeological research projects , such as Stanford's Digital Michelangelo project 1 or IBM's Pieta project, 2 archaeologists are becoming aware of the advantages of using 3D visualization tools. Archaeologists can now use the data recorded during excavations to generate virtual 3D models suited for project report presentation, restoration planning, or even digital archiving, although many issues remain unresolved. Until recently, the cost in time and money to generate virtual reconstructions remained prohibitive for most archaeological projects. At a more modest level, some archaeologists use commercially available software, such as PhotoModeler (http://www.photo-modeler.com), to build simple virtual models. These models can suffice for some types of presentations, but typically lack the detail and accuracy needed for most scientific applications. Clearly, archaeologists need more flexible measurement techniques, especially for fieldwork. Archaeologists should be able to acquire their own measurements simply and easily. Our image-based 3D recording approach offers several possibilities. 3-8 To acquire a 3D reconstruction, our system lets archaeologists take several pictures from different viewpoints using a standard photo or video camera. In principle, using our system means that archaeologists need not take additional measurements of the scene to obtain a 3D model. However, a reference length can help in obtaining the recon-struction's global scale. Archaeologists can use the resulting 3D model for measurement and visualization purposes. Figure 1 shows an example of the types of pictures possible with a standard camera. In developing our system, we regularly visited Sagalassos, a site that is one of the largest archaeological projects in the Mediterranean. The site consists of elements from a Greco-Roman period spanning more than a thousand years from the 4th century BC to the 7th century AD. Sagalassos, one of the three great cities of ancient Pisidia, lies a few miles north of the village Aglassun in the province of Burdur, Turkey. The ruins of the city lie on the southern flank of the Aglassun mountain ridge (a part of the Taurus mountains) at an elevation of several thousand feet. Figure 2 shows Sagalassos against the mountains. A team …