They become hard to see and impossible to touch. There is a technical problem as well: scanners such as the Selene Photometric Stereo System record surface relief in extraordinary detail, hundreds of millions of pixels in a single scan, and until now no open online viewer could handle such data at that scale.
Tactum Viewer is the answer to both. It is a free and open source viewer built around a simple idea: to let conservators, researchers and the public examine the surface of an object as if they were holding it. It runs in the browser on any modern computer, phone or tablet. There is nothing to install and nothing to download.
Developed by Jorge Cano, Tactum remains under active development. Factum Arte will continue its research and development during 2026, building on the open source platform released under the Apache License 2.0. The platform is freely available to Factum Foundation, the Selene Circle community and anyone else who wants to use it.
Short video demonstrating Tactum © Factum Foundation
Nature printed moss, Alois Auer, Der polygraphische Apparat, Vienna, 1853. Private collection of Adam Lowe
Tactum is a Latin word meaning touch or ‘a touch’. It is from the verb tangere, to touch. It is most familiar today from the biblical phrase Noli me tangere (“do not touch me”). We chose the name because museums work to preserve their objects by forbidding touch while in a digital space ‘Tactum’ can now provide the opportunity to handle works of art.
You can turn the object, bring it close to study a detail and step back to see the whole. You can move the light across the surface in real time, with the mouse or with a finger movement that is linked to camera on your computer, and watch the shadows reveal marks invisible to the naked eye. You can also measure distances and height differences in real units, trace an elevation profile along a line and switch between the fine relief or the more general shape of the surface.
Tactum streams the scan in tiles, like an online map, so very large surfaces work on ordinary hardware. It follows the IIIF standard, so the same dataset also opens in familiar viewers such as Mirador. The viewer is designed for objects usually treated as flat: paintings, drawings, manuscripts, prints, copper plates, fossils, wax and cuneiform tablets. Selene systems are already in use at institutions such as the Bodleian Libraries, where the ARCHiOx project records the surfaces of items in the collections.
The live demo presents the nature-printed moss above, scanned at 12.3 µm per pixel, around 200 million pixels of surface. We invite you to pick up the lamp and look.
EXPLORE THE SOURCE CODE ON GITHUB
Tactum Viewer. Copyright © 2026 Jorge Cano.
Released under the Apache License 2.0. Source code available on the Factum Foundation GitHub account.
