This talk includes three parts. In Part I, I will briefly introduce a number of imaging techniques for 3D structure reconstructions at different scales (including tissue, cellular, subnanometer, and atomic levels). In Part II, a couple of image processing algorithms will be presented, in order to extract features of interest for geometric modeling. Part III is mesh generation, an essential step for finite element method. I will introduce two approaches for mesh generation: Delaunay triangulation and Octree-based method.