3D Scanners

Freiburg Cathedral: Reconstructing Melting Faces

The Freiburg ‘Maulaufreisser’ (mouth gaping gargoyle) and his 3D twins

The figure of speech, “carved in stone” implies eternal and indestructible, sadly, this doesn’t apply to the unique architectural decoration features of the Freiburg Cathedral in Germany. In fact, very real ravages of time are chipping away especially at the exterior masonry. Weathering and increasing air pollution are taking their toll on the variously shaped reliefs and sculptures, transforming the medieval building into an extensive continuous construction site of melting faces.


Since 1890, the Münsterbauverein (Cathedral Construction Association) has been responsible for the stone exterior and the building conservation of the Freiburg Cathedral. Because of this, the association has been looking after  Münsterbauhütte (Cathedral Builders’ Hut) which is more than 800 years old. This is where stone masons and stone carvers apply traditional craftsmanship to maintain and preserve the Freiburg Cathedral. In addition, the versatile 3D data of the SmartScan makes its very own contribution to the conservation of this church monument.

A stony data backup

The Freiburg Münsterbauverein is in the possession of a very special treasure: The collection of over 4000 copies of sculptures and building fragments of the Freiburg Cathedral. These pieces are of inestimable value for both restoration projects as well as for the purpose of scientific documentation. At the start of the very extensive gypsum collection of the Münsterbauverein, nobody thought about photographs or three-dimensional scan data. Even today, stone cutters are still using this archive of patterns and forms in order to reconstruct any damaged shapes.



Among the numerous plaster casts is a gargoyle known under the names of ‘Maulaufreisser’ (gaping mouth gargoyle), ‘Akrobat’ (acrobat) and ‘Zanner’ (mascaron). The purpose of its 3D scan data is to support the work of the Münsterbauverein in a special way — for the creation of souvenirs made of different materials.

3D scanning for a digital archive

For the three-dimensional capture of the ‘Maulaufreisser’, the SmartScan of AICON 3D Systems with a field of view of 600 mm and a camera resolution of 2 megapixels, is called into action. This scanner is specifically designed for the high demands of the scanning of works of art and cultural artefacts as it not only generates precise, high-resolution 3D models but also allows for the texturing of the object surface in its true colors.


Thanks to the SmartScan’s modular configuration, the cameras (color or black and white) and the measuring fields are individually adjusted to the client’s needs. In the case of this project, the scanner was moved around the ‘Maulaufreisser’ in order to capture it from all sides. As an alternative option for a partially automated capture, the turnTABLE-300 can be used. It is specifically designed for scanning heavy objects, such as a gargoyle with a weight of 250 kg.

First, the SmartScan captures the gargoyle from all sides. Thanks to the flexible sensor configuration allowing for simultaneous scanning processes at angles of 30°, 20° and 10°, even object areas which are difficult to access can be scanned swiftly and precisely.

The AICON Software OptoCat then aligns the individual images based on the contour of the gargoyle and combines them into a coherent triangle mesh. This 3D data set can subsequently be prepared in the desired size for any further processing, e.g. for model making, or in this project, for the creation of customized silver jewelry.

3D replica in any size

Using the 3D data of the SmartScan, a modern archive of digitized sculptures and construction components can be created, thus expanding the application possibilities in connection with the original or plaster replicas. The third dimension of a figure or a relief provides a detailed basis for scientific analysis and documentations. The data serves as a fundamental support for professional restoration or reconstruction tasks.


The virtual copy of the gargoyle can be adjusted to any scale and serves as basis for model and mold making or rapid prototyping. Using the digital templates, true to original replica in any desired size can be created with the help of milling templates, casting molds or 3D printers. These replicas can be used in many ways, e.g. in exhibitions, in study collections or as souvenirs.

The Freiburg Münsterbauverein uses the SmartScan data of the ‘Maulaufreisser‘ to create 1:1 replicas made of concrete, smaller copies made of stone repair mortar and jewelry figurines made of silver. The ‘Maulaufreisser’ donates his ‘salary’ to a good cause, all sales proceeds go back into the conservation of the Freiburg Cathedral.

Click here for further information about 3D applications in arts and culture.

About AICON 3D Systems GmbH

AICON 3D Systems is one of the world’s leading providers of optical camera-based 3D measuring systems. The company, founded in 1990, develops and distributes systems for the business areas of inspection and testing including car safety and tube inspection. Since gaining Breuckmann GmbH in August 2012, the product range also includes scanners for 3D measurement of complex geometries. On 1 April 2016, the AICON 3D Systems GmbH has joined Hexagon Manufacturing Intelligence, a leading global provider of information technologies that drive productivity and quality across geospatial and industrial enterprise applications.

The digital acquisition and documentation of cultural masterpieces is increasingly gaining importance, be it in architecture, fine arts, archaeology or paleontology. The contact-free 3D scanning technology of Breuckmann Scanners works in museums as well as at archaeological sites. It allows handling delicate objects with the utmost care and provides detailed 3D data with high-resolution color textures for thorough studies without using the original. Breuckmann Scanners are not 3D measuring systems bought “off the rack”, but rather are characterized by their high degree of flexibility. The scanner configuration is adjusted exactly to the customer’s requirements.

For more information, please visit www.aicon3d.com

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