Cultural heritage preserves multiple layers of stories
accumulated for ages. Some of these stories are readily
recognizable, while others are hidden deep within,
requiring meticulous uncovering. Digital non-destructive
diagnosis and 3D image analysis technologies have been
breakthroughs in this excavation.
The comprehensive report on the results of the
conservation treatment of and research on Hahoe Masks
and Byeongsan Masks of Andong (National Treasure),
which kicked off in 2021, was completed this summer.
During this project, the non-destructive diagnosis was
actively utilized to identify the inner structures, defects,
and restoration traces of the masks and to facilitate their
digital restoration. What exactly is the non-destructive
diagnosis? It refers to the technology for digitally analyzing
the inner structures and conditions of cultural heritage
without inflicting damage and for archiving the related
data. Both the exterior and interior of an artifact can be
thoroughly investigated through X-ray imaging, X-ray
CT scanning, and high-precision 3D scanning. The non
destructive diagnosis enables us to accurately identify
the structural defects and current conditions of individual
artifacts and provides the necessary data for artifact
restoration and conservation planning
Digital Non-Destructive Diagnosis of Cultural Heritage
The non-destructive diagnosis largely consists of three
parts: X-ray imaging, X-ray CT scanning, and high
precision 3D scanning.
First, X-ray imaging is similar to the X-rays used in the
healthcare sector. Instead of the film typically used for
radiology testing, imaging plates are employed to convert
X-ray energy, which penetrates into the artifact and is
absorbed in accordance with its density, into digital images.
Imaging plates are superior to film in terms of sensitivity
and can produce higher-quality images with 5-20% lower
radiation doses, thereby reducing the artifact’s exposure to
radiation. Soft and hard X-rays are selectively used based
on the artifact’s material type. The former is suited for
identifying the inner structure of relatively thin objects such
as paintings, wood, and thin metal, while the latter is applied
to stone, thick metal, and other objects with high density.
X-ray CT scanning rotates a firmly secured artifact, captures
hundreds or thousands of images, and converts them into
3D digital data using a high-performance computer. Such
3D digital data can visually reproduce the inner structure of
the artifact in three dimensions and include a wider range
of information such as the density of the inside. This 3D
visualization technology is being widely used for research on
cultural heritage, as it enables the quantitative analysis of a
variety of information related to the artifact.
High-precision 3D scanning is a technology engineered to
accurately measure the exterior of an artifact and archive the
measurements in 3D data, thereby enabling the permanent
conservation and different applications of data. This technology
also provides color information in addition to the detailed
appearance and plays an instrumental role in digital restoration
and archiving. Data obtained through 3D scanning can be
utilized for artifact restoration or research and help perform
thorough analysis without incurring any damage to the artifact.
Digital Archiving and Utilization of Cultural Heritage
by Non-Destructive Diagnosis I
The digital archiving of cultural heritage in Korea is still going
on from the mid-2000s. Databases, which mainly contained photos and descriptive text in the past, have evolved to
encompass 3D scanning-based digital archiving through the
3D database establishment project for cultural heritage by
Korea Heritage Service in 2012. However, obstacles remain
and have impeded a comprehensive understanding of the
inner structures, manufacturing techniques, and conservation
conditions of cultural heritage due to the concentration on
data acquisition.
The convergence of various NDT technologies is essential to
overcome these obstacles. For example, X-ray CT and high
precision 3D scanning can be used in tandem, as X-ray CT is
capable of reproducing the inner structure of the artifact in
three dimensions and high-precision 3D scanning can archive
data on the exterior of the artifact (detailed appearance, color
information, etc.). By converging the two datasets, digital
archiving and the utilization of both the inner structure and
exterior color data become possible.
For 3D data convergence modeling, separate datasets
are obtained from 3D surface scanning and X-ray CT
scanning, which are then integrated into one 3D model.
Deviations between the two datasets are analyzed to assess
compatibility. The 3D convergence modeling process is as
follows.
Digital Archiving and Utilization of Cultural Heritage
by Non-Destructive Diagnosis Ⅱ
The non-destructive diagnosis and image analysis technologies
were applied to the recent conservation treatment and
restoration of Hahoe Masks and Byeongsan Masks of Andong
(National Treasure). For Byeongsan Mask Eul, the condition
of the applied reinforcing material was thoroughly examined
using X-ray CT and 3D scanning data analysis, after which the
reinforcing material was removed and a new modeling plan for
a support was established. The support was then created using
3D printing and utilized for the conservation and management
of the mask. The most notable advantage of this technology
was that it enabled diverse virtual simulations and quick
corrections while minimizing physical contact with the artifact.
The non-destructive diagnosis and image analysis proved to
be highly useful for accurately identifying the condition of the
artifact and establishing effective restoration and conservation
plans accordingly.
Cultural heritage displays layers of history accumulated for
ages and thus requires a careful and meticulous approach
throughout the conservation and analysis processes. The
non-destructive diagnosis and image analysis technologies
are making significant contributions to revealing the long
hidden secrets of cultural heritage and archiving them for
future generations. It is expected that such technologies will
continue to evolve and more and more stories of ancient
times will be digitally archived.
01 Bride Mask from Hahoe Masks and Byeongsan Masks of Andong (National Treasure)
02 Traces of repair discovered on the interior of the Bride Mask through NDT
03 X-ray CT scanning
04 3D convergent modeling of the deer-shaped horn cup excavated from
Marisan Mountain Tomb 45 in Haman-gun
05 Support fixture modeling for Hahoe Masks and Byeongsan Masks of Andong
(National Treasures)
06 3D convergent modeling process