Optical Measuring (white-light scanning)

Nowadays, valuable cultural treasures are increasingly being measured by means of white-light scanning in order to produce digital “back-up copies.” These copies are more accurate in detail than was possible in the photogrammetric measuring used previously. Optical measuring thus takes over the role of traditional plaster replicas.

Beams of light are projected onto the object. A stereo-camera records the lines of projection on both sides and derives measuring points from them with great precision. In this way, millions of points in space (point clouds) are generated. A triangulated mesh is generated between them, making it is possible to depict the surface of the object accurately. By means of registration marks, individual measurements from various spatial angles are put together. As a result, objects of up to many meters in size can be measured with pinpoint accuracy.

The data set is saved as an STL file* and can be processed further using rapid prototyping** or with machining tools (5-axis milling). The Atos system from the company Gom has particularly proven itself for the measuring of complex objects.

* STL = Stereo-lithography
** “Rapid prototyping” in the Kunstgiesserei includes: laser sintering, stereo-lithography or 3D printing

Laser Scanner

With the laser scanner, it is possible to generate a 360-degree view with an accuracy of 5mm to 240m. It can be used in indoor and outdoor spaces, e.g. in the planning of exhibitions or for art in architecture projects. In the field of architecture, it can, for example, provide services helpful for restoration work when building plans are not available. The laser scanner is also able to capture the texture of surfaces.  

Measuring with Computer Tomography

Using computer tomography, we position 900 to 1,200 x-ray images on a rotary disk across a central axis. The individual cross-sections are assembled into a three-dimensional data set from with the object can be reconstructed with a level of detail of up to 2 microns (two-thousandths of a millimeter). The point clouds obtained in this manner are here also supplemented to create a spatial mesh.

Since its invention in 1971, computer tomography has been important particularly in the field of medicine. Its advantage in comparison to optical measuring is that it makes it possible to obtain information about the interior of an object. Hollow cavities that are not recognizable from the outside as well as indentations and complex surfaces can, therefore, also be depicted. Computer tomography is generally suitable for small objects up to 30cm in size.