RTI has become a popular imaging technique that enables subtle variations in surface topography and texture to be visually appreciated. Small surface variations can witness text, inscriptions and other dimensional features that are abraded or otherwise worn to the point of near invisibility. RTI image capture consists of capturing a series of images of an object. During the series of captures, the camera and the object remain fixed. Each image is captured illuminated by a non-diffuse, constant-intensity point light source that is positioned at different points distributed over the surface of a hemisphere whose diameter is roughly 10 times the cross section of the object. The object is at the center of the hemisphere’s plane and the optical axis is coaxial with the hemisphere’s radius perpendicular to the plane.

RTI lighting systems are usually implemented with several dozen light sources affixed to the surface of a dome. The requirement that the dome be much larger than the object usually means that RTI is applied to small objects, or it is implemented by manually moving a single light source around while capturing, which is time-consuming and less than ideal. Imaging an ordinary sized medieval manuscript is not possible with most available RTI domes, as it would require a dome about 8 feet in diameter. Such a dome would difficult to transport, assemble, and use.

MegaVision solved the problems of usability and portability by creating not a dome, but a pivoting arc that sweeps out a dome. While the Arc of the Firmament™ may be deployed solely as a practical solution for large RTI capture, it may also be integrated with MegaVision’s multispectral imaging system. This enables the RTI and multispectral images to be registered thereby enhancing the effectiveness of each modality.

The diameter of the Arc is nominally 8 ft (2.44 M). The Arc is comprised of 15 segments for easy disassembly and shipment. The segmented design makes it practical to offer custom sizes. Do not hesitate to inquire about other diameters.

The stands are adjustable to facilitate matching the rotational axis with the scene plane and can include supports for MegaVision’s multispectral lights.

Pivoting the arc is performed manually and ball-detente indexing make manual movement repeatable.