# SIFT-Based Depth Estimation for Accurate 3D Reconstruction in Cultural Heritage Preservation
## 1 Introduction
\begin{table}
\begin{tabular}{p{113.8 pt} p{113.8 pt} p{113.8 pt}} \hline
**Preservation Techniques** & **Advantage** & **Disadvantage** \\ \hline \multirow{8}{*}{1. Measuring by hand} & & 1. Damage risk: Direct contact can damage delicate artifacts. 2. Error-prone: Human error leads to inaccurate measurements. 3. Time-consuming: Measuring intricate artifacts by hand is a slow process. 4. Difficult to replicate: Inconsistency of the technique hinders replication. 5. Limited data: Hand measurements miss subtle details. \\ \cline{2-3}  & & 1. Limited field of view: Kinect’s narrow field of view might require multiple capture and stitching. 2. Operational range: Kinect’s limited range might not be suitable for large artifacts or specific distance requirements. 3. Resolution limitations: Kinect might not capture intricate details. 4. Accuracy for complex shapes: Kinect may struggle with capturing highly intricate shapes or deep cavities. \\ \hline \multirow{8}{*}{3. 3D laser scanner} & 1. Unmatched precision: 3D laser scanners offer the highest level of accuracy for digital preservation. 2. Speed and efficiency: Laser scanners capture data quickly, streamlining the process. 3. Richness of data: 3D laser scanners capture geometry and color for visually rich models. \\ \cline{2-3}  & 1. Accessibility: Photogrammetry is accessible with a camera and software. 2. Portability: Photogrammetry is highly portable due to the use of a camera. 3. Color and texture preservation: Photogrammetry captures realistic textures and colors. \\ \cline{2-3}  & 1. Accessibility: Photogrammetry is accessible with a camera and software. 2. Portability: Photogrammetry is highly portable due to the use of a camera. 3. Color and texture preservation: Photogrammetry captures realistic textures and colors. \\ \cline{2-3}  & 2. Processing power: Photogrammetry can be computationally demanding. 3. Limitations with certain surfaces: Photogrammetry struggles with reflective, transparent, or featureless surfaces. \\ \hline \end{tabular}
\end{table} 
Table 1: Recent techniques used in the preservation of 3D cultural heritage. remains a significant drawback. In addition to their expense, these scanners require bulky equipment, making them impractical for use in confined spaces such as caves. In the photogrammetry technique, commercial software such as AgiSoft 2.2.0, Reality Capture 1.5 (Unreal), and ReCap 2024 (AutoDesk) uses multiple 2D images taken from a DSLR camera to generate a 3D model. Unlike 3D laser scanning, the accuracy of the 3D models produced by photogrammetry depends on the overlapping of point clouds between images. Generally, each image must have an overlap ratio of 70-80% with adjacent images to ensure precise reconstruction. Consequently, capturing high-quality images for photogrammetry requires skilled photographers with experience in the technique. The preservation of tangible cultural heritage through 3D reconstruction using 2D images tends to follow a structured workflow. The input data consist of multiple 2D images captured from different viewpoints around the object. The process typically involves the following steps: (1) image registration, which involves aligning overlapping 2D images to ensure proper positioning; (2) depth computation, which involves managing image orientation and calibration for accurate depth estimation; and (3) 3D reconstruction, which involves generating a 3D model using point clouds and stereo-dense matching.