# Graphic Reconstruction of a Roman Mosaic with Scenes of the Abduction of Europa
## 2 Examples of Mosaic Reconstruction  
Digital reconstruction methods have been used for many years in the preservation and representation of cultural heritage, including mosaic reconstruction [8; 9; 10]. Traditionally, mosaic reconstructions relied on drawings and photographs for documentation. While laser scanning offered a promising 3D approach, including for mosaics, it resulted in low-quality mosaic images. To overcome this limitation, Structure from Motion (SfM) was introduced [11; 12]. This technique utilizes regular cameras to generate high-quality 3D models with color information, proving to be a valuable tool for in-depth mosaic research. The results are high-resolution orthographic images, demonstrating SfM's effectiveness for detailed mosaic documentation. The evolution of technology and the introduction of new software tools have significantly broadened the application of photogrammetry in the realm of cultural heritage, particularly in the documentation, analysis, and reconstruction of mosaics. These advancements have streamlined the photogrammetric process, incorporating algorithms from the field of computer vision to enhance automation and efficiency in creating 3D reconstructions from photographs. This shift towards more accessible and automated photogrammetric methods marks a notable advance in the preservation and study of mosaics, demonstrating the critical role of photogrammetry in the conservation of cultural heritage assets [11; 12; 13]. Utilizing SfM photogrammetry for mosaic preservation, we can create accurate 3D models of these artworks by capturing overlapping images from multiple viewpoints with just a standard compact camera, enhanced by georeferenced data for precise location mapping. Reference points are necessary for the orientation and placement of photographs in the spatial coordinate system. This step is critical for generating georeferenced and metric 3D models that accurately represent the mosaic's surface (cloud of points, orthophoto plan...). For effective computer processing and analysis, maintaining the spatial coherence of models is required from point cloud to orthophoto mosaics [14]. Photogrammetry is widely used to capture mosaics' data with a variety of specifications. The use of recording devices, such as drones, makes it possible to capture the image data of mosaics whose dimensions extend over large areas of antiquity [15], or to capture and process the details of mosaics through images, process them with software, and identify the materials used in the tesserae. In the study by [PERSON] et al. [16], the researchers created a digital record that allows for the identification of original sections and restored areas. Photogrammetry can be used in the analysis of tesserae used for recurring decorative patterns of the mosaic [17]. Photogrammetry not only aids the conservation of the mosaics, but also enables further studies directly on the digital model and provides valuable visual and metric data for interpretation and presentation. Visual information acquisitions of mosaics are useful in combination with 3D representations. A 3D model that combines mosaic details (shape, size, color) with informative data (materials, period) can improve the understanding of the site's history and the planning of future restoration and conservation [18]. Also, in restoration, the colors are important for data interpretation concerning the chromatic behavior of the materials [19]. Authors [PERSON] and [PERSON] [20] present a simple method for reconstructing mosaics that is not metrically accurate. The non-metric approach captures the mosaic without the use of photogrammetry or laser scanning. Digital acquisition was performed using an ordinary digital camera. For larger mosaics, a larger number of photos were taken with overlapping edges, which were then combined to obtain the high-resolution full size required to show the details of the mosaic and the print quality.