Fluorescence microscopy is a widely used tool in modern biomedical research. It has recently been improved by fluorophore localization methods such as photoactivated localization microscopy (PALM) and stochastic optical reconstruction microscopy (STORM), resulting in nanoscale-resolution images that enable one to study the structure and dynamics of sub-cellular components. This project is aimed at characterizing the 3D structures of subcellular components, such as clathrin-coated pits. The project will consist of several stages: PSF modeling of a PALM microscope, localization accuracy calculations by means of Cramer-Rao bounds, 3D localization of real data, 3D rendering of the results.