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  <front>
    <journal-meta>
      <issn pub-type="ppub">1613-0073</issn>
    </journal-meta>
    <article-meta>
      <title-group>
        <article-title>Object to Enrich Cultural Heritage Knowledge Graph</article-title>
      </title-group>
      <contrib-group>
        <contrib contrib-type="author">
          <string-name>Shenghui Wang</string-name>
          <email>shenghui.wang@utwente.nl</email>
          <xref ref-type="aff" rid="aff1">1</xref>
        </contrib>
        <contrib contrib-type="author">
          <string-name>Daria Kulyk</string-name>
          <xref ref-type="aff" rid="aff1">1</xref>
        </contrib>
        <contrib contrib-type="author">
          <string-name>Delaram Javdani Rikhtehgar</string-name>
          <xref ref-type="aff" rid="aff1">1</xref>
        </contrib>
        <contrib contrib-type="author">
          <string-name>Dirk Heylen</string-name>
          <email>d.k.j.heylen@utwente.nl</email>
          <xref ref-type="aff" rid="aff1">1</xref>
        </contrib>
        <contrib contrib-type="author">
          <string-name>Carolien Riefe</string-name>
          <xref ref-type="aff" rid="aff0">0</xref>
          <xref ref-type="aff" rid="aff1">1</xref>
        </contrib>
        <aff id="aff0">
          <label>0</label>
          <institution>Leiden University</institution>
          ,
          <addr-line>Wassenaarseweg 52, 2333 AK Leiden</addr-line>
          ,
          <country country="NL">The Netherlands</country>
        </aff>
        <aff id="aff1">
          <label>1</label>
          <institution>University of Twente</institution>
          ,
          <addr-line>Drienerlolaan 5, 7522 NB Enschede</addr-line>
          ,
          <country country="NL">The Netherlands</country>
        </aff>
      </contrib-group>
      <pub-date>
        <year>2023</year>
      </pub-date>
      <fpage>6</fpage>
      <lpage>10</lpage>
      <abstract>
        <p>Virtual Reality (VR) technology has the potential to enhance cultural heritage experiences by providing immersive environments. This study proposes a novel approach that combines VR environments with eye-tracking data to identify users' points of interest in exhibition paintings. By leveraging gaze patterns, valuable insights into user preferences, behavior, and attention can be extracted and integrated into the cultural heritage knowledge graph. To achieve this, an object detection model is fine-tuned on historical artwork datasets, and statistical tests are conducted to analyze gaze-object correlations. The results demonstrate the feasibility of using an object detection algorithm to detect points of interest and reveal correlations between eye gaze patterns and meaningful objects in paintings. This approach has the potential to enrich the knowledge graph, enabling more personalized and immersive experiences for art enthusiasts and visitors.</p>
      </abstract>
      <kwd-group>
        <kwd>Image object detection</kwd>
        <kwd>Eye gaze</kwd>
        <kwd>Virtual reality</kwd>
        <kwd>Knowledge Graph</kwd>
        <kwd>Cultural Heritage</kwd>
      </kwd-group>
    </article-meta>
  </front>
  <body>
    <sec id="sec-1">
      <title>-</title>
      <p>CEUR
ceur-ws.org</p>
    </sec>
    <sec id="sec-2">
      <title>1. Introduction</title>
      <p>
        Virtual Reality (VR) has revolutionized the preservation and exploration of cultural heritage [
        <xref ref-type="bibr" rid="ref1">1</xref>
        ],
yet its potential to enrich the cultural heritage knowledge graph remains largely untapped. To
bridge this gap, we propose an innovative approach that combines immersive VR environments
with eye-tracking data to identify users’ points of interest in exhibition paintings. By leveraging
users’ gaze patterns, we can extract valuable insights into their content preferences, behavior,
and attention [2, 3]. This information can be seamlessly integrated into the cultural heritage
knowledge graph, contributing to a more comprehensive representation of the artworks.
      </p>
      <p>The stored information in the knowledge graph can then be utilized to customize the
information provided to exhibition visitors about the artworks. Studies have shown that providing
LGOBE
(C. Riefe)
https://people.utwente.nl/shenghui.wang (S. Wang); https://people.utwente.nl/d.k.j.heylen (D. Heylen);
CEUR
Workshop
Proceedings
elaborate and content-specific information about artworks enhances understanding and
aesthetic appreciation [4, 5]. By leveraging the insights gained from the enriched knowledge
graph, museums and cultural institutions can tailor the descriptions and information provided
to visitors, matching their preferences and increasing engagement and satisfaction. This
approach aligns with the transition from collection-oriented museums to visitor-oriented ones [6],
recognizing the importance of catering to diverse visitor preferences and interests.</p>
      <p>However, eye-tracking data alone does not provide semantic meaning to the areas of gaze.
While it indicates where someone is looking, it lacks details about the specific objects within the
paintings that capture users’ attention. This limitation makes it challenging to infer the type of
content users are focused on and whether their fixations primarily concentrate on background
elements or meaningful areas of the painting.</p>
      <p>To address this challenge, manual annotation of objects by human observers is a possible
solution. However, it becomes impractical for larger datasets due to the time-consuming nature
of the task. To overcome this, we propose combining gaze data with an automated object
detection model to add meaning to users’ eye gaze. Our research aims to achieve two objectives:
assessing the feasibility of using an object detection algorithm to detect points of interest and
investigating the correlations between eye gaze patterns and meaningful objects in paintings.</p>
      <p>To achieve these objectives, we first fine-tune an object detection model on a historical artwork
dataset and evaluate its predictions on the 19 paintings presented in a special VR exhibition [7].
We then utilise participants’ eye-tracking data collected during a user study using this exhibition
to conduct statistical tests on meaningful areas of the paintings and determine the influence of
object types on gaze duration.</p>
    </sec>
    <sec id="sec-3">
      <title>2. Object detection</title>
      <p>In this study, we fine-tuned the Faster R-CNN model, 1 pre-trained on MS COCO dataset,2 using
a subset of the Open Image V7 dataset3 that contains images relevant to our study. Specifically,
we focused on European fine-art paintings from the 17th century, categorized as portrait, genre,
and landscape, as they closely resemble the ones presented in the VR exhibition. We sampled
images of 11 Open Image categories (see Table 1 for the size of each category) that frequently
appeared in the artistic descriptions of these paintings. These categories were chosen based on
their relevance and occurrence in the SemArt dataset.4 In our adapted model, we adjusted the
output layer to accommodate 12 categories, including 11 categories of interest and one category
representing the background.</p>
      <p>For the VR exhibition, we manually annotated the 19 paintings using the same 11
categories. Figure 1 (a) provides an example of detected objects, marked in dark blue with their
corresponding confidence scores, compared to the manual annotation marked in light blue.
The performance of the fine-tuned object detection model on these paintings is summarized
1The Fast R-CNN model is a Convolutional Neural Networks (CNN)-based object detection framework that relies on
a Region Proposal Network for eficient region detection within images [ 8].
2https://cocodataset.org/
3https://storage.googleapis.com/openimages/web/factsfigures_v7.html
4https://github.com/noagarcia/SemArt
in Table 1.5 The model demonstrated satisfactory performance in detecting various object
classes, including small human-related objects like hair, eyes, and mouths. This indicates the
potentials of transfer learning and fine-tuning for such classes. However, the model exhibited
lower accuracy in detecting non-human classes, particularly animals, due to the limited training
examples available and the small size of animal objects in the VR paintings. The performance in
non-human classes such as trees, buildings, hats, and dresses also sufered, potentially attributed
to the unresolved cross-depiction problem and the scarcity of training examples for garments.</p>
    </sec>
    <sec id="sec-4">
      <title>3. Gaze-object correlation</title>
      <p>As reported in [7], a total of 31 participants visited 19 paintings in the VR exhibition. For each
painting, the eye-gaze data of each participant was recorded and represented as a heat map with
a 100 x 100 grid overlaying the painting. The heat map captured the duration of the participant’s
eye gaze within each cell of the grid. Figure 1 (b) provides an example of an eye-gaze heat map
from one participant, overlaid with manually annotated bounding boxes.
5Detailed overview of these average precision metrics can be found at https://cocodataset.org/#detection-eval.</p>
      <p>For each gaze point, we determined whether it fell within any of the manually annotated
object bounding boxes (“on-object”) or outside of them (“out-object”) for the painting. For gaze
points marked as “on-object,” we collected information on the corresponding object categories
and the duration of that gaze point. By analyzing the collected data, we calculated the average
duration of gaze on and of objects for each participant across all paintings, as well as the
specific gaze duration on individual objects.</p>
      <p>To ensure the reliability of our analysis, we confirmed the normality of the data using the
Shapiro-Wilk test.Subsequently, a paired t-test revealed a significant positive average diference
in gaze duration between objects and areas without objects ( 31 = 6.33,  &lt; 0.001 ). This finding
indicates that, on average, participants exhibited a selective focus on meaningful areas of the
paintings, demonstrating their interest and engagement with the artwork. Additionally, a
oneway ANOVA test demonstrated a significant diference in the average time spent on diferent
categories of objects ( (2) = 6.607,  &lt; 0.001 ). Notably, participants, on average, allocated
significantly more time to viewing buildings compared to human heads and figures.</p>
    </sec>
    <sec id="sec-5">
      <title>4. Conclusion</title>
      <p>This study presents a novel approach that combines VR environments, eye-tracking data, and
object detection to enhance the cultural heritage knowledge graph. By fine-tuning an object
detection model on historical artwork datasets, it is possible to identify and assign semantics to
potential areas of interest within exhibition paintings. The statistical tests conducted reveal
correlations between eye gaze patterns and meaningful objects depicted in the paintings. This
approach holds great potential for enriching the knowledge graph, thereby paving the way of
providing a more immersive and personalized experience for art enthusiasts and visitors.</p>
      <p>Next, we will further explore the development of more advanced models and gather more
suitable training data to improve the eficiency for object detection in paintings. Additionally,
we will utilise semantic technologies to explicitly integrate detected objects and their associated
knowledge via manual annotation or entity linking, further enriching the culture heritage
knowledge graph. In the future, we aspire to develop eye-gaze-based interactions that will
usher in personalised, immersive experiences within the realm of VR.</p>
    </sec>
    <sec id="sec-6">
      <title>Acknowledgment</title>
      <p>The authors would like to express their gratitude to Museum Rembrandthuis for their support
and for providing the essential exhibition information. They would also like to thank Claudia
Alessandra Libbi and Rens van der Werf for their development of the VR exhibition utilized in
this study.
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[5] H. Leder, C. C. Carbon, A. L. Ripsas, Entitling art: Influence of title information on
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[7] D. Javdani Rikhtehgar, S. Wang, H. Huitema, J. Alvares, S. Schlobach, C. Riefe, D. Heylen,
Personalizing Cultural Heritage Access in a Virtual Reality Exhibition: A User Study
on Viewing Behavior and Content Preferences, Adjunct Proceedings of the 31st ACM
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[8] S. Ren, K. He, R. Girshick, J. Sun, Faster R-CNN: Towards Real-Time Object Detection with
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    </sec>
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