The earliest map of Sardis was made by Borra in 1750. Despite his limited time and resources, the map compares well with that drawn by Butler’s expedition in 1913. The Harvard-Cornell expedition also created maps of the site that have been used every summer since 1962 and depict all of the major topographical features. When experimentation with computer technology began in the early 1990s, the Expedition decided to digitize hand-drawn maps transforming them into computerized versions, which can be modified to meet specific needs. Satellite imagery and global positioning imagery were combined to create digital maps of the area, allowing archaeologists greater flexibility in studying the site, its topography, the orientation of its buildings, and the settlement patterns of the region. Digital technology has also been used to create computer models of individual structures such as a painted tomb chamber. This digital model completely integrates photography and computer drawing, indicating an integrative "new phase of graphic recording."