|M.Sc Student||Khokhlov Maxim|
|Subject||Multi-Scale Stereo Photogrammetry Method for Fractographic|
Analysis Using a Scanning Electron Microscope
|Department||Department of Mechanical Engineering||Supervisors||Professor Anath Fischer|
|Professor Daniel Rittel|
|Full Thesis text|
Current systems for fractographic analysis rely mainly on two-dimensional visualization methods, namely the visualization of microscope images from Scanning Electron Microscopes (SEM). The lack of three-dimensional information prevents the determination of important quantitative features such as local roughness and precludes a deeper comprehension of the failure mechanisms.
This thesis describes a new multi-scale stereo-photogrammetry method for inspection of fracture surfaces based on SEM images. The method enables the reconstruction of complete 3D fracture surfaces and provides interactive visualization of the multi-scale structure, thus offering better insight into fracture surfaces at different levels of detail. In particular, a new method has been developed for geometric reconstruction of a 3D textured mesh from SEM stereo images. The mesh is represented as a 3D geometric multi-resolution structure. The sampled images are represented in the form of a multi-scale hierarchical textured structure. Thus, the global shape of the sample is represented by a 3D mesh, while its micro details are represented by textured data. This multi-scale and hierarchical structure enables interactive multi-scale navigation of the 3D textured mesh. The Regions of Interest (ROI) can actually be inspected interactively at different scales by means of optical or digital zooming. Thus, the digital model can be visualized and the behavior of the 3D material can be analyzed interactively.
The contributions of this research include: (a) providing a new 3D multi-scale reconstruction method to be applied on SEM stereo images; (b) providing a new visualization module for multi-scale inspection, modeling and analysis of micro-structures for a variety of materials; and (c) providing 3D insight into and better understanding of fracture phenomena for material micro-structures.
The feasibility of the proposed method is demonstrated on samples of different materials, and a performance analysis is applied on the resulting multi-scale model. The roughness calculation was verified against roughness calculation applied to an optical profilometer.