Hop on board as we continue our journey Around the World in 80 Models! We began our itinerary at Sketchfab headquarters in New York and are working our way through Europe, Africa, Asia, Oceania, South America, and North America. To catch up on past destinations, check out the rest of the Around the World in 80 Models series.
This week we rejoin medical radiologist Marc Ghysels in the Democratic Republic of the Congo, where he shows us how he used X-ray scans to digitize a wooden ancestor figure from the Boyo culture.
Eastern Democratic Republic of the Congo: Boyo Ancestor Figure
Hello, my name is Marc Ghysels, I am a medical radiologist from Brussels with a special interest in African art. Actually the first African statue that has stuck in my mind was a head [Fig 1] featured on the cover of Joseph Cornet’s book, Art of Africa (Phaidon, 1971).
The 98 cm tall wooden statue represented an ancestor of the Boyo people, who used to live in the eastern part of the Congo (DRC), on the shores of Lake Tanganyika, where it was photographed in situ by the Belgian anthropologist Luc de Heusch in 1953.
The present owner of the statue (which can be seen at the far left in the line-up of six statues in this old photograph [Fig. 2]) entrusted it to me at the beginning of 2011. He wanted it to be examined by means of an X-ray scanner to detect any evidence of restoration or termite damage or any other radiological anomalies.
With the 3,300 slices obtained by X-ray scanning, I was able to create a 3D model of the statue using InSpace, an interactive medical imaging application (by HipGraphics), equivalent to the free and open-source OsiriX software (by Pixmeo).
In 2016, some five years after the X-ray scan, 164 VRT (Volume Rendering Technique) images [Fig. 3] generated by InSpace were exported to PhotoScan (by Agisoft: Standard Edition, version 1.2.3) running on an Apple iMac 27″ 5K. The aim was to construct an opaque 3D digital model that could be manipulated in real time on the web and viewed even on an iPhone or an iPad.
Of the 164 VRT images (2,048 x 2,048 pixels) exported to PhotoScan, 135 were 3 series of 45 views taken every 8° rotating around the X-, Y- and Z-axis of the statue, supplemented by 29 enlarged views focused on previously poorly documented parts [Fig. 4].
After some 20 hours of data processing, the 3D model constructed by PhotoScan seemed optimal. It was uploaded by this application directly to the Sketchfab website so that other African art enthusiasts, whether they be collectors, art historians, anthropologists, museum curators, or sculptors… could examine it at their leisure from all angles.
The shading and textural rendering obtained with the PBR (Physically Based Rendering) tools recently made available to Sketchfab users gave a more accurate representation [Fig. 5] of the way light interacts with the model, decreasing the visual gap between the look of the Boyo statue in real life and its uploaded 3D model on Sketchfab.
For the statue’s owner, this technique offers the great advantage of providing a sort of “three-dimensional condition report” on Sketchfab, which is much more informative than the two photographs that were usually supplied in the past. If the statue suffers damage in the course of an exhibition or transport, he will be able to avoid any contestation from the insurance company about possible earlier damage.
To see more of Marc’s models here on Sketchfab, check out his profile!