artifact Archives ⋆ X-Reality: University of Michigan XR

Photogrammetry for the Stearns Collection

Photogrammetry results from the Stearns Collection: Here a drum is captured, and visible are the original digital photographs taken inside Stearns, the drum generated as a point cloud, the point cloud developed into a 3D mesh, and then a fully textured 3D model.

Donated in 1899 by wealthy Detroit drug manufacturer, Frederick Stearns, the Stearn’s Collection is a university collection comprised of over 2,500 historical and contemporary musical instruments from all over the world, with many of the instruments in the collection being particularly fragile or one of a kind. In 1966 Stearns grew to include the only complete Javanese gamelan in the world, and being home to such masterpieces, the Stearns collection has become recognized internationally as unique. In 1974, due to concerns about preservation and display, much of the collection was relocated out of public view. Once residing in Hill Auditorium, the majority of the collection now sits in storage inside an old factory near downtown Ann Arbor.

The current location of the Stearns Collection. Photo Credit: www.dailymail.co.uk

Current preservation efforts have involved photographing the collection and making the nearly 13,000 resulting images available online. However, over the past year the Duderstadt Center has been working with Chris Dempsey, curator of the Stearns Collection and Jennifer Brown, a University Library Associate in Learning & Teaching, on a new process for preservation: Utilizing Photogrammetry to document the collection. Photogrammetry is a process that relies on several digital photographs of an artifact to re-construct the physical object into a digital 3D model. While traditional methods of obtaining 3D models often utilize markers placed atop the object, the process of Photogrammetry is largely un-invasive, allowing for minimal, and sometimes, no direct handling of an artifact. Models resulting from this process, when captured properly, are typically very precise and allow the viewer to rotate the object 360 degrees, zoom in and out, measure, or otherwise analyze the object in many cases as though it were actually in front of them.

Equipped with a high resolution digital SLR camera, Jennifer traveled to the warehouse where much of the Stearns collection is now held to document some of the instruments that are not currently on display and have limited accessibility to the general public. Feeding the resulting images into an experimental Photogrammetry software developed for research purposes (“Visual SFM” and “CMVS”), Jennifer processed the photos taken of various instruments into high resolution 3D models that could eventually be placed on the web for more accessible public viewing and student interaction.

The Kelsey Museum – Visualizing Lost Cylinder Seals

2D illustration of one of the seal imprints used to generate a 3D model

The Kelsey Museum houses a collection of more than 100,000 ancient and medieval objects from the civilizations of the Mediterranean and the Near East. Margaret Root, curator of the Greek and Near Eastern Collections at the Kelsey Museum, came to the Duderstadt Center with the impressions of several ancient cylinder seals. A cylinder seal is a small cylindrical tool, about one inch long, used in ancient times to engrave symbols or marks. When rolled in wet clay, the seal would leave an impression equivalent to a person’s “signature.” These signatures were commonly used to sign for goods when trading. Some of the earliest cylinder seals were found in the Mesopotamian region.The Kelsey Museum wanted to re-create these seals from the impressions to generate 3D prototypes or for use in a digital exhibit. These exhibits would allow visitors to the Kelsey to experience the cylinder seal tradition first-hand by providing seals and clay to roll their own impressions. The problem was these seals tend to get lost over time so the museum did not have the original seals, only the imprints.

To recover the seal’s three-dimensional form, Margaret Root provided the Duderstadt Center with an outline of the imprints in Adobe Illustrator. From the outline, Stephanie O’Malley of the Duderstadt Center added varying amounts of grey to generate a depth map, where the darkest areas were the most inset and the lightest areas were the most protruding. With a depth map in place she was then able to inset areas on a cylindrical mesh in Zbrush (a 3d sculpting software) to re-create what the cylinder seal (the example seal is the “queen’s seal” ) would have looked like. Shawn O’Grady has printed one of these seals already.

A 3D render of the re-created cylinder seal.

The Duderstadt Center has since obtained the new Projet 3D printer, and plans are now underway to eventually print one of these on the Projet since it has a much higher print resolution and these seals are typically quite small.

To check out more at the Kelsey Museum, click here.