Stonehenge is a fascinating monument. In addition to other interpretations of its purpose, histories have noted that it once may have functioned as a very accurate time and season “clock.” Recently, English Heritage, the custodians and conservators of Stonehenge and other historical monuments, buildings and ancient sites across England, undertook a project to use 3D scanning to develop a digital version of the 5000 years old monument.

The digital models are being used for a number of purposes. They provide a precise baseline to enable English Heritage to monitor the physical condition of the monument, which is subjected to daily weathering. They are also a valuable resource to anyone wishing to produce reconstruction models, drawings or images for public understanding and interpretation and to create animation sequences. This will allow experts from English Heritage to fly virtually through and over the monument from different perspectives to aid their studies of the stones – and for their work on the proposed new visitor centre at Stonehenge.

Together with Atkins Mapping and Archaeo-Environment Ltd., the Greenhatch Group, specialists in topographical surveys and building surveys using 3D laser scanning, used short- and long-range laser scanners from Z+F UK and Leica Geosystems, along with other survey equipment, to digitally capture all the visible faces of the standing and fallen stones, as well as the tops and faces of the lintels, to a resolution of +/- 0.5 mm. Surveys of all the stone faces to this level of accuracy have never been achieved before. The surrounding landscape was also captured as part of the overall project to create the most accurate 3D digital model ever of the monument.

The data captured by the scanners was read into Geomagic Studio software where it was processed to create highly accurate 3D digital polygon mesh models of the individual stones and the surrounding landscape. The individual stones could then be placed digitally in their correct positions to create an accurate 3D virtual model of the whole monument, which in turn could be placed accurately within the virtual model of its real-world context.

Commenting on the scale of the project and its benefits, Andrew Dodson, director, Greenhatch Group, said, “Many of the raw 3D point cloud files from the scans of the stones comprised up to 50 million points, or 1.5 GB of data, each. Without the point cloud processing capabilities of Geomagic Studio we would not have been able to convert them into the accurate 3D digital polygon models that this project demanded.

“As well as helping people to understand how Stonehenge was built and how it has been changed at certain times in the past”, he added, “the 3D virtual models that have been produced with Geomagic Studio hold out the promise of enabling people to find out the secrets that lie within the eroded surfaces of these ancient stones. They will therefore add greatly to the English Heritage store of knowledge of Stonehenge.”

Geomagic
www.geomagic.com