Voxeljet - True-to-detail temple model from 3D printer

stripe light scanning by night © Trigonart

3D model with reconstructions © Trigonart

printed plastic part © Trigonart

model on the exhibition in Berlin © Trigonart

For fifteen years the team from the Egyptian Museum in Berlin dug in the Sudanese desert and restored historic statues, sculptures and temples. The "Naga - City of Kings" exhibition, which is held in the Kunstforum of the Berliner Volksbank foundation, provides information about this work until 18 December 2011. Visitors can even glimpse an actual model of the famous Hathor Chapel, a true-to-detail depiction made of plastic, which was produced by voxeljet using the 3D print method.

As many questions that arose during the excavation work in Naga would have been left unanswered using conventional methods , the archaeologists decided to turn to state-of-the-art technologies. The restoration of the world famous Hathor Chapel highlights the contribution of computers, scanners and 3D print systems. Advanced testing with an elaborately designed virtual model was used to obtain information regarding different courses of action, so that the project for the restoration of the temple could be precisely coordinated and tested.

In order to obtain a meaningful model, the remaining parts of the Hathor Chapel had to be scanned as part of a first step. Not an everyday project, explains Dipl. Ing. Thomas Bauer of TrigonArt, a Berlin scanning specialist: "To measure a structure of this size in a completely three-dimensional form is both a demanding and time-consuming project. We used high-precision 3D stripe light scanning in the Sudanese desert; the work that was involved in compiling the full chapel took three weeks, after which 2,500 individual scans and 1.5 billion recorded pixels went back to Berlin."

The stripe light scanning system used for this project has an excellent track record for the touchless 3D measuring of art and cultural items. The 3D scatter plots that are obtained as part of this process feature very high information depth with a very low error tolerance. The resulting measurement accuracy guarantees highly precise 3D scan results, which are required in particular for the representation of the smallest details or for taking measurements. In this context, the virtual model of the Hathor Chapel also impresses with maximum richness of detail and size accuracy.

The model produced by the computer offered the archaeologists an opportunity to disassemble the building into its parts right on the screen, and develop appropriate measures and techniques to save the structure, which was in danger of collapsing. Without this technology, it would not have been possible to restore the chapel and all of its collapsed building parts in such an authentic manner. Visitors looking at the chapel, parts of which were carefully rebuilt with reproduced plastic replica, do not see the 15 years of work carried out by archaeologists and computer specialists. To achieve a restoration that maintains the highest degree of authenticity, the team purposely stayed away from very extensive reconstructions.

True-to-detail model from 3D printer

The fact that very few people would be able to get a sense of the successful restoration of the Hathor Chapel on site resulted in the request for a real model, which would also be presented at the Berlin exhibition. More specifically, the request centred on an actual physical model that could reflect the details of the chapel in a manner as true-to-detail and precisely as possible. It did not take long to establish contact with the Augsburg-based 3D print specialists at voxeljet. Here, at one of the largest service centres in Europe, the company has specialised in the on-demand production of sand moulds for metal casting as well as models made of plastic. Small-batch and prototype manufacturers in a variety of branches of European industry appreciate the fast and cost-effective manufacture of their casting moulds and 3D models based on CAD data.

"I must admit - the request to print a historic temple was not something we see every day. But once we obtained all the information from TrigonArt and analysed the existing data material, we thought that it would be quite possible to implement the project at the requested quality," says Dr. Ingo Ederer, CEO of voxeljet technology GmbH.

Once the CAD data for the temple model were available, the project was started directly with a 3D VX800 high-performance printer. This equipment is predestined for generating building components that require absolute attention to detail and high-precise representation of contours. The plastic model of the Hathor Chapel, with dimensions of 481x825x584 millimetres and a scale of 1:10, was obtained from the CAD data using a layering process. Following a print time of approximately 18 hours, the VX800 generated the entire chapel from thousands of micrometre-fine layers.

Following the unpacking period - a process during which excess material is removed from the model - the plastic model became reality: "The physical model of the Hathor Chapel exceeds even the highest expectations. The richness of detail in our scans finds its full expression in the plastic model. Another advantage is the mechanical stability of the model, which promises a long service life," says Mark Praus from TrigonArt.

Interested parties who make the trip to Berlin until 18 December 2011 can see the quality of the 3D print of the Hathor Chapel for themselves, and they can also find out how the use of trendsetting technologies can lead to impressive results in an "old" science such as archaeology. Not least thanks to innovative high-tech processes, it is now possible to preserve the restored temple ruins of Naga, the 2000 year old city of kings in the empire of Meroë, for generations to come.

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