Document Type : Original Research Paper
Authors
Faculty of Architecture and Urbanism, Imam Khomeini International University, Qazvin, Iran
Abstract
Background and Objectives: In cultural heritage documentation, the first and most fundamental step involves producing accurate records and maps of the current condition of heritage assets. Recent scientific advancements have enabled the application of innovative tools and methodologies that not only reduce the time required for documentation but also significantly enhance its accuracy and quality. Among the approaches that have attracted increasing attention in recent years is photogrammetry. In Iran, in parallel with global developments and growing international interest in digital heritage documentation, several of the country’s most significant cultural monuments have been documented using photogrammetric techniques. Nevertheless, despite the increasing scholarly and practical attention devoted to this field and the widespread global adoption of photogrammetry, its application within the domain of Iranian cultural heritage—particularly UAV-based photogrammetry—remains limited. Given the vast extent of Iran’s cultural heritage and the growing importance of digital heritage documentation, greater attention to heritage photogrammetry, both theoretically and operationally, is essential. Accordingly, the present study aims to elucidate the process of employing UAV photogrammetry for the surveying and three-dimensional modeling of historical and cultural monuments in Iran.
Methods: Due to the outstanding universal value of the Dome of Soltaniyeh in Zanjan and the absence of prior digital documentation using photogrammetric methods, this UNESCO World Heritage monument was selected as the case study. This applied, case-based research was conducted using stereophotogrammetry (stereo-pair photogrammetry) supported by UAV photogrammetry through sequential stages of data acquisition, image processing, and three-dimensional modeling.
Findings: Practical implementation of the study demonstrated that an image overlap ratio of 60–80%, as emphasized in similar studies, is essential during data acquisition and aerial imaging to prevent gaps and voids in the three-dimensional model of the Soltaniyeh Dome. Furthermore, due to the dome’s curvature and large scale, employing multiple flight platforms with varying UAV gimbal angles resulted in improved image mosaicking and model reconstruction. In addition, the appropriate spatial distribution of control and check points across different elevation levels ensured satisfactory accuracy in both horizontal and vertical dimensions. The achieved errors—approximately 2 cm in the horizontal dimension and 0.83 cm in the vertical dimension—confirm the reliability and precision of the adopted methodology. Ultimately, highly accurate two-dimensional and three-dimensional digital records of the Soltaniyeh Dome, capable of continuous updating, were produced for the first time, thereby facilitating the conservation and change management of this World Heritage property.
Conclusion: The findings demonstrate the considerable capability of UAV photogrammetry for the accurate documentation and modeling of heritage monuments, despite the geometric complexity characteristic of traditional Iranian architecture. Consequently, this method can—and should—be widely employed to produce reliable metric documentation of immovable cultural heritage assets. As a non-destructive technique that does not require physical contact with the monument, UAV photogrammetry provides updatable digital documentation that supports future knowledge-based conservation, monitoring, planning, and management of heritage properties, including the World Heritage Site of Soltaniyeh. Given its accessibility, cost-effectiveness, and compatibility with other documentation techniques, widespread and substantial adoption of this method is anticipated in the near future. Furthermore, integrating heritage digitization requirements into national guidelines for heritage registration dossiers and conservation projects will accelerate the adoption and dissemination of such effective documentation tools. Enhanced interdisciplinary collaboration among specialists in architecture, conservation, and geomatics sciences will likewise contribute significantly to the proper implementation of this methodology and to the production of accurate and reliable heritage documentation.
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© 2026 The Author(s). This is an open-access article distributed under the terms and conditions of the Creative Attribution-NonCommercial 4.0 International (CC BY-NC 4.0)
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