@phdthesis{oai:kitami-it.repo.nii.ac.jp:00009075, author = {TASHI}, month = {Mar}, note = {Reverse engineering mimics critical features of a given object and creates its accurate (or enhanced) virtual model (digital model) and replica (physical model). It is often used to digitize existing objects in different engineering fields and preserve significant cultural artifacts. In conventional reverse engineering, a 3D scanner scans the exposed surfaces of a given object, which results in a relatively large point cloud. The noise and outlier points are removed from the point cloud before the surfaces are reconstructed. The reconstructed surfaces undergo geometric modeling, which results in a digital model of the object. This kind of reverse engineering requires sophisticated devices (a 3D scanner) and complex computations. It is challenging to make a reverse engineering process less dependent on sophisticated devices and complex computations. This study proposed a novel reverse engineering method to overcome the challenges. The proposed novel reverse engineering method uses an analytical approach to create a noise- and outlier-free point cloud of a given object. The analytical approach is based on a recursive process that requires two types of input. The first type of input consists of two parameters denoted as instantaneous distance and instantaneous rotationnal angle. These parameters vary in each iteration of the recursive process. The other input of the recursive process consists of three parameters: center point, initial distance, and initial angle. They remain constant for all iterations. The recursive process produces a small point cloud to model some features of a given object, even when the mathematical representations are unknown. In this case, the instantaneous rotational angle can be increased linearly after each iteration, and the instantaneous distance can be varied using simple and well-known mathematical functions. The modeling ability of the proposed reverse engineering method is validated by comparing two point clouds of the same shape. The first point cloud is created using the parametric equation for a given shape (e.g., circle, ellipse, spiral, astroid, and straight lines). The second point cloud of the same shape is created using the recursive process. Significant cultural artifacts can be digitized using the proposed reverse engineering method. This study considers reverse engineering some patterns belonging to the Ainu, the indigenous people of Hokkaido. They use fourteen elementary motifs (e.g., "Ayus, " Developing a Novel Reverse Engineering Method Suitable for 3D Printing and its Application to Preserving Cultural Heritage "Morew, " "Sik," and "Utasa") to create unique patterns with which they decorate their houses, clothing, ornaments, utensils, and spiritual goods. The mathematical representations of these motifs and the underlying patterns are unavailable. The proposed reverse engineering method is applied to create point clouds representing some selected Ainu motifs. For each point cloud, the instantaneous rotational angle is increased linearly and the instantaneous distance is adjusted as needed using some simple mathematical functions. This way, a database of Ainu motifs is prepared. Some point clouds are exported to a commercially available 3D CAD system. After simple geometric modeling (rotation, translation, extrusion, and copying), the point clouds are transformed into digital models (virtual models) of the respective motifs and patterns. The digital models are used to manufacture replicas of the respective motifs/patterns with an ordinary 3D printer. This way, this study digitally preserves the craftsmanship of Ainu motifs and patterns. The proposed reverse engineering method equally applies to artifacts other than Ainu motifs. It is demonstrated by producing a virtual model and replica of an ancient ewer (i.e., a 3D shape). The processes involved in the proposed reverse engineering method (recursive point cloud creation process, point cloud coordination, solid CAD modeling, and replica manufacturing using a 3D printer) do not require sophisticated devices. They are free from heavy computations, unlike conventional reverse engineering processes. The thesis is organized into six chapters. The first chapter presents the background, scope, objectives, and contribution of this study. The second chapter provides a literature review on reverse engineering, its application to 3D printing, and Ainu motifs/patterns. The third chapter describes the methodology of this study. The fourth chapter details applications of the proposed reverse engineering method, particularly for creating a virtual/physical prototype of Ainu motifs/patterns and other significant cultural artifacts. The fifth chapter discusses the implications of this study and highlights future work. The final chapter concludes this thesis.}, school = {北見工業大学}, title = {Developing a Novel Reverse Engineering Method Suitable for 3D Printing and its Application to Preserving Cultural Heritage}, year = {2021}, yomi = {タシ} }