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.