Reconstruction of Metal Objects - 3D Photogrammetry and Clay Coating

This work focuses on the development of a reconstruction process using 3D photogrammetry for metal objects, which are often difficult to scan in three-dimensional (3D) due to their shiny, smooth and featureless surfaces. Usually, expensive 3D scanning technologies are used for high accuracy reconstructions. This research presents a novel approach using clay powder to improve the geometric accuracy of 3D reconstructions through a coating process, a first in the literature. Twelve metal objects with cubic, cylindrical and spherical geometries were selected for the study. They were photographed in a controlled environment using a turntable, camera and 18-135 mm lens. 3D reconstructions of these objects were obtained initially without coating and then by applying clay powder. The reconstructions were then compared for geometric accuracy and mesh quality. The main findings from the study show that clay coating significantly improves the geometric accuracy of the reconstruction process. In addition, it also improves the homogeneity of the mesh structures. These improvements were confirmed by deviation analysis, which compared the models generated by the reconstruction process with computer-aided design (CAD) models drawn according to the actual dimensions of the objects. The study highlights the potential of clay coating as a viable alternative method to improve geometric accuracy in the 3D reconstruction process.