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Digital Survey Technology & 3D Printing Used to Create Model of Ancient Mayan Acropolis

Located in the northern Petén Department of Guatemala near the Salsipuedes River, La Blanca is an ancient Mayan settlement, and one of its main archaeological focal points is the Acropolis, which was built as a residence for the city’s rulers during the Late Classical Period (AD 600-850). It consists of three buildings, two with thatched roofs and one with a soil layer, on a platform reached by a large staircase. Research into the settlement has been frequent over the years, which is why in 2010, a Visitor’s Center was built there as part of the La Blanca Project framework. Tourists receive support there, while locals have a good place to participate in cultural heritage workshops and view educational materials.

Southeast area of the Acropolis.

One thing it was lacking, however, was a scale replica of the Acropolis to use as a tool for the dissemination of Mayan architectural heritage. This would have been difficult to achieve before digital survey techniques, but 3D technology is changing how we document and preserve cultural heritage sites. A trio of researchers from the Universitat Politècnica de València (UPV) published a case study about using 3D printing for this purpose at La Blanca, and how the team was able to document the complex using digital survey technology “to obtain a high-fidelity model of the Acropolis’ buildings.”

The objectives were to improve the contents of the Visitor Center’s exhibition hall with a model of the Acropolis, perform an in-depth study of “all the procedures used to obtain the Acropolis reality-based model and propose a workflow that could be used in similar cases,” and test these resources for use in dissemination of Mayan history.

The project actually began in 2012 with a Faro Focus3D S120 scanner, which is a fast but compact Terrestrial Laser Scanner (TLS) that can provide efficient 3D measurements. Between 2012 and 2015, three digital survey campaigns were conducted at various parts of the Acropolis, for a total of 118 scans.

Acquisition Parameters and final Point Cloud Model

“Having acquired these scans, we carried out the point clouds registration in a laboratory and obtained the reality-based Point Cloud Model of the Acropolis,” the researchers stated. “This model showed a very high geometric accuracy and was useful for extracting 2D classic drawings and for obtaining 3D polygonal mesh models.”

It was important to create a methodology for reverse modeling of the Acropolis, which started with the laser scanning data.

“In general, it is possible to print 3D objects starting from a traditional 3D model that has been modeled directly (as in the case of the model of a building we are designing) or from a reality-based 3D model that has been obtained from real data acquired by laser scanning or by digital photogrammetry,” they explained.

Reverse modeling software can create a 3D polygonal mesh from a point cloud model, but the first mesh typically needs to be optimized to achieve a model with high enough quality that it can be 3D printed. Optimizing and building the 3D mesh model of the Acropolis was tough because there was a lot of redundant data from earlier scanning, and the highest parts of the wall lacked data, as “the thatched-roofs system caused occlusion areas,” but they managed.

“First, the 3D point model of the Acropolis was exported into .ptx format in 9 parts. Then, every section of the model was imported into the software 3D System Rapidform with a ¼ factor of reduction. In the same software, we built separately 9 different high-poly meshes,” they wrote. “The heterogeneous structure of the single 9 meshes was an additional problem caused by the higher or lower redundancy of data acquired in different field seasons.”

Reality-based mesh of the Acropolis.

They completed a “global re-meshing” of these nine to reduce the number of polygons in the final model and homogenize the average size of their edges, as well as their number and distribution. Then each mesh was processed separately to fill boundaries and negate topological errors, like overlaying or redundant polygons. Once all the meshes were combined, the team had a medium-poly model of the Acropolis.

They still needed to integrate the 3D model with these procedures, and turned to reverse modeling and other software tools to finish it. They completed a manual retopology of the model’s boundaries, which allowed them to obtain simplified contours; these were then used “as references for the direct modeling of the missing sections of the Acropolis.” They had to then homogenize the structures of both meshes using Luxology Modo and 3D System Rapidform, and then merged the meshes into one model.

Integration of the model. 4a: Retopology of the boundaries; 4b: Direct modeling; 4c: Resultant mesh; 4d: Smoothing the mesh.

Maxon Cinema 4D’s sculpting tools were used to improve the model’s homogenization, which also “helped emphasize the difference between the reality-based parts of the model and the directly modeled surfaces that had been undetected by the laser scanner.” Finally, the terrain mesh was integrated with the help of a geometric modeling tool, and the 3D model of the Acropolis, “consisting of 6,043,072 polygons with a homogeneous structure over the entire mesh,” was ready to be 3D printed. The team did note a slight mesh deviation between one of the original high-poly meshes and the final model, but the FDM 3D printer they used could handle it.

The final Acropolis model.

The team conducted a few print tests with different configurations and scales in order to select the proper settings before printing the entire model out of PLA, the results of which were very accurate when compared with the virtual 3D model.

“The missing parts of the Acropolis, undetected by laser scanner and then manually reconstructed, appeared to be perfectly integrated in the 3D printed version of the model and showed, at the same time, their diversity from the reality-based parts of the model,” the researchers wrote.

“From the analysis of these tests, we concluded that the representation of the Acropolis was satisfactory.”

The last test, with 1:100 scale and 0.3 mm accuracy, offered the best fidelity, so the team printed the Acropolis model with these parameters. It was printed in 17 different parts, as the final measurements of 90 x 70 cm were too large for the print bed; however, this ended up being helpful when it came time to transport the model to La Blanca. It was reassembled there, and sits in the middle of the La Blanca Visitor Center’s exhibition hall, protected by a transparent plastic dome, for all to enjoy.

Final 3D printed model of the Acropolis.

“Today, this physical replica of the Acropolis is an important resource that allows the visitors to have a complete view of the main complex of the site, which is not easy in the Guatemalan jungle,” the researchers concluded. “It also provides an exclusive view of some parts of the Acropolis, already studied by researchers and now protected with a soil layer to ensure their preservation. Moreover, it is a useful resource for supporting dissemination and also serves as a teaching resource for student visitors.”

The post Digital Survey Technology & 3D Printing Used to Create Model of Ancient Mayan Acropolis appeared first on 3DPrint.com | The Voice of 3D Printing / Additive Manufacturing.

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Google, Stratasys and CyArk Use 3D Scanning and 3D Printing to Preserve Cultural Heritage

Google Arts and Culture is collaborating with Stratasys and non-profit CyArk to preserve 3D scans and 3D prints of some of the world’s most cherished heritage sites. Google’s Open Heritage Project lets you virtually explore sites from all over the world through a fun and immersive experience. Myanmar’s Bagan, the Brandenburger Tor in Berlin, Chichén Itzá you can be an armchair explorer in each of them. Test it out by flying through some of the sites here. 

Wat Yai Chai Mongkhon Temple Thailand.

What’s more, the files are available for download so that teachers in classrooms or museums worldwide can show them off. Kinesthetic learners, the curious and the idle can use them to play with and touch some of the world’s most notable sites. The parts have been crafted for the J750 3D printer which can do multi-color and multi-materials.

The company says that,

“Google Arts and Culture is the restoration of rare plaster casts initially discovered by A.P. Maudslay during the late 1800s in Guatemala. For more than 100 years, these relics were housed across storage facilities in the British Museum. By leveraging 3D laser scanners to virtually re-assemble each, designers successfully reconstructed these items in physical form with Stratasys 3D printing – later allowing representations to be easily viewed by a wider audience online.”

An impression of Stela E of  the Mayan Quirigua site in Guatemala taken by Alfred Maudslay

Alfred Maudslay went to Quirigua in 1881 and was enthralled by the Mayan civilization and the remote Quirigua site. In total, he would undertake six Mayan expeditions. Above in the image, we can see an impression of Stela E of the Quirigua site. Over ten meters tall it was erected on the 22nd of January in 771 AD. From then on it let all passers-by know that the ruler K’ak’ Tiliw Chan Yopaat ruled here.

“From the beginning, Maudslay understood that a three-dimensional record would be needed if the surviving Maya remains were to be fully analysed by future generations of archaeologists and epigraphers. To this end, he set about producing a complete set of moulds of the monoliths. Once shipped back to London, the moulds and resulting plaster casts were used to produce exact drawings of the glyphs, which were published with the photographs in his Archaeology (1889–1902), later bound to form a comprehensive record of the Maya ruins of Central America. The result was a magnificent work of documentation which, in the words of Maudslay’s biographer, is ‘valued as highly by modern scholars as it was by their predecessors a century ago’.

In the 1880s archeology, especially of a remote foreign site was far more Grand Theft Auto than it is today. At the time Mayan culture was little understood in the West and Mandalay’s exploration of the site, excavation and impressions were instrumental in our understanding Mayan language and culture. Mayan stelae can be found throughout Mayan lands sometimes standing ten meters or more these objects are thought to tell histories and reinforce Mayan rule. Celebrating kings and commemorating events these stelae gave real insight into the politics of Mayan life. The important Quirigua site also held squat zoomorphs or animal inspired shapes that show gods in the Mayan world. By taking their impressions and cataloging them in his tome; an impression of the site was transported around the world to be studied. Stratasys, Google, and CyArk are now doing a very similar much more high tech thing with 3D scanning and 3D printing. In Maudlays footprints they are finding a way to let us all study impressions of an unfathomable past.

Alfred Maudslay at Chichên Itzá.

Bryan Allen, a Design Technologist at Google, said: 

“The project was to explore physically making these artifacts in an effort to get people hooked and excited about seeing pieces in a museum or research context. That’s when we turned to 3D Printing.” “With the new wave of 3D Printed materials now available, we’re able to deliver better colors, higher finish, and more robust mechanical properties; getting much closer to realistic prototypes and final products right off the machines. When we talk to arts and culture preservationists, historians, and museum curators, they’re all absolutely amazed by the ability to fabricate these things with such high fidelity via 3D printing technology,”

Rafie Grinvald, Enterprise Product Director of Rapid Prototyping, Stratasys, said:

“Combining rich colors and translucency in a single print, designers and engineers can build models with heightened levels of accuracy and realism – mirroring opaque or transparent structures, and even complex materials like rubber.”

CyArk has already done some amazing work worldwide in 3D scanning many of the world’s most well-known objects. Will more 3D scans mean that one could at one point download a museum? In the past, we’ve written about 3D Printing being used to let the visually impaired feel exhibits, and how exhibits could be touched by everyone, seen how Berlin’s museums have used 3D printing and 3D scanning and seen how you can restore things through 3D scanning and printing,  We’ve also delved much deeper, looking into the ethics of 3D scanning exhibits. Could we open up a 100 3D printed British Museums worldwide? Could every classroom have access to many of the world’s most important objects? What do you think?