Researchers from Ritsumeikan University and the University of Science and Technology Beijing, have developed an advanced edge-highlighting method aimed at enhancing the clarity of visualized 3D scanned objects.
Led by Professor Satoshi Tanaka and involving key team members Ms. Yuri Yamada, Dr. Satoshi Takatori, and Prof. Liang Li, the group’s innovative approach addresses common visualization issues by separately emphasizing sharp and soft edges in complex point cloud data, overcoming limitations seen in traditional methods. Published in Remote Sensing, these findings promise clearer representations of intricate 3D objects, particularly useful for preserving and studying cultural artifacts.
Explaining the research’s broader significance, Prof. Tanaka notes, “Our 3D edge extraction approach is not merely an improvement but rather an extended technique that captures areas not covered by traditional methods. For archaeologists and historians, this tool opens new possibilities for specialized visual analysis of cultural heritage objects. For the general public, it offers a deeper understanding of historical cultural sites, serving as a technology for enhancing exhibitions in museums and art galleries.”
Advancing cultural heritage visualization through enhanced 3D scans
With the rapid advancements in 3D scanning, especially through photogrammetry and laser scanning, researchers can now produce accurate digital representations of complex objects, including cultural artifacts, as detailed point cloud data. These scans allow for an in-depth analysis of structural details but can present challenges in visualization, as traditional edge-highlighting methods often produce excessive lines that reduce visual clarity.
To address these challenges, the team developed a dual-edge highlighting approach. This dual-edge extraction technique uses separate thresholds to distinguish sharp edges from softer, rounded ones.
Sharper edges are identified through high-curvature zones, while soft edges, essential in rounded or subtler contours, are represented with a secondary threshold. By applying distinct visualization techniques to each, the team captures a fuller range of details without the clutter or thickness that can occur when soft edges are visualized as wide bands.
Opacity color gradation further enhances visualization by introducing a color and transparency gradient within soft edges, creating a “halo effect” that naturally distinguishes front and background edges. Depth perception is thus markedly improved, allowing intricate internal structures to be observed more clearly.
To achieve this efficient rendering, the team used stochastic point-based rendering (SPBR), a technique that enables real-time visualization without the intensive depth sorting typically required in 3D processing.
In testing, the technique was applied to high-value cultural heritage sites, including Japan’s Tamaki Shinto Shrine and Indonesia’s Borobudur Temple.
Compared to traditional edge-highlighting, the dual-edge method provided enhanced visual clarity, accurately representing both exterior and interior structures without increasing computation times. The halo effect and edge-thinning significantly clarified intricate details, proving essential for preserving cultural heritage objects.
Interactive rendering speeds ensure the technique’s functionality for real-time exploration, supporting applications like “see-through” visualization. Rather than relying on standard transparency, this method uses edge clarity to bring internal structures into view without losing visual depth, a significant improvement in comprehensibility.
Future enhancements will focus on refining threshold-setting processes and expanding color gradation pathways to further detail subtle features.
Plans to incorporate machine learning into this technique aim to combine 3D restorations with information from sharp and soft edges, particularly beneficial in digitally reconstructing artifacts recorded in 2D formats.
This new visualization approach opens a valuable pathway in 3D scanning applications, offering researchers sharper tools for digital preservation, analysis, and exploration of cultural heritage with unprecedented clarity and depth.
Novel 3D scanning approaches for cultural preservation
Over the years, various developments have been reported in the 3D scanning for cultural preservation, highlighting the technology’s potential. Back in 2022, Ukrainian activists began using 3D scanning to digitally preserve cultural heritage sites endangered by Russian military actions.
Through the Backup Ukraine initiative, around 6,000 volunteers used the Polycam app to capture 3D models of monuments and historical sites, safeguarding them against potential destruction. Launched by co-creator Tao Thomsen in partnership with UNESCO and Blue Shield Denmark, the initiative quickly expanded as volunteers documented war damage across Ukraine. UNESCO reported significant destruction to religious and historical sites, underscoring the urgent need for digital preservation to protect Ukraine’s cultural legacy.
Previously in 2018, In 2018, Google collaborated with CyArk, a nonprofit dedicated to preserving historical sites at risk from conflict or natural disasters, to launch the Open Heritage project on Google Arts & Culture.
Through CyArk’s 3D laser scanning expertise, this project generates highly detailed models of cultural landmarks, accessible via Google’s platform. Using advanced techniques like LiDAR and photogrammetry, CyArk achieves millimeter-level precision, supporting future restoration efforts. As Google Arts & Culture’s first venture into 3D heritage sites, Open Heritage also provides model data for developers interested in creating immersive and educational experiences around these digital artifacts.
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Featured image shows dual 3D edge extraction for 3D scanned point cloud data of the cave of the Zuigan-ji Buddhism temple in Miyagi Prefecture, Japan. Image via Ritsumeikan University.
