Bentley Systems, a software provider for infrastructure, announced that its Bentley Pointools technology was used to visualize and analyze a detailed laser scan survey at Stonehenge – one of the world’s oldest built environments.

The laser scan with point spacing of 0.5 millimeters resulted in an enormous data resource of 850 gigabytes. The task of further examining this ancient infrastructure to discover more about it was awarded to ArcHeritage, part of the York Archaeological Trust in the United Kingdom as part of a project commissioned by English Heritage.

Preliminary examination of the meshed models identified individual tool marks more than 5,000 years old, but it was evident that the data contained more prehistoric artwork carved onto the surface of the stones. The team decided to visualize the original point-cloud data and created a workflow using Bentley Pointools. It enabled large datasets to be loaded, facilitating an examination of the full resolution data. The software’s shading function resulted in the discovery of 71 carvings of Bronze Age axes not seen in more than three thousand years.

“We needed a software solution that would handle and visualize vast quantities of survey data,” said Marcus Abbott, a member of the ArcHeritage Geomatics and Visualization team. “Bentley Pointools is capable of loading both 3D mesh and point-cloud data. Furthermore, Bentley Pointools’ full suite of measuring tools and unique visualization tools were crucial to the success of the Stonehenge project. The discovery of unrecorded prehistoric rock art on the stones was first realized in Bentley Pointools.”

Richard Zambuni, Bentley global marketing director, geospatial and utilities, said, “Stonehenge is one of the world’s great buildings surviving from prehistory – it is not fanciful to call this amazing public building ‘infrastructure,’ and although we know very little about how this structure was designed, constructed, and used, cutting-edge infrastructure software such as Bentley Pointools can be used to give us more insight into this astonishing edifice. The powerful layering and shading functions in Bentley Pointools allowed carvings of Bronze Age axe heads and daggers that were invisible to the naked eye to be visualized and provided sub-millimeter accuracy to the archaeologists documenting Europe’s greatest Stone Age building.”

The discovery of the carvings at Stonehenge was realized through the team’s use of Bentley Pointools’ Plane Shading function to create a greyscale band 7.5 centimeters wide. This band was moved at 1-millimeter intervals through the data. As it moved, it created a high-quality rendering of the plane shaded image. The team repeated the process 75 times to complete a full color change for every point in the data.

Depending on the position in relation to a preset camera plane, each point was assigned a greyscale value, allowing subtle features to be visible. When the images were combined into an animation and played back, the carvings, which were invisible to the naked eye, were seen fading in and out. Once the extent of the carvings was identified, the team deployed the measuring and point location tools to accurately plot the carvings to the Ordnance Survey grid.

Read a case study on the ArcHeritage Stonehenge project online.