Abstract
In the last decade the study of resolved stellar populations has improved significantly due to the high quality images obtained with HST, capable of generating deep colour-magnitude diagrams (CMD) even in dense stellar regions in neighboring galaxies. To take advantage of this increasing quality and quantify of data, sophisticated CMD analyzes, which combine two dimensional CMD modelling and statistical comparisons, have been employed to objectively extract the physical parameters of an stellar population. Using CMDs obtained with HST/WFPC2 and the aforementioned approach our group has been working in the following topics: 1) modelling the structure of the Galaxy, especially the thick disk and stellar halo; 2) constraints in the LMC Star Formation History (SFH); 3) determination of age, Z, (m - M)_0, E(B - V) and positional dependence of the Present Day Mass Function (PDMF) slope in rich LMC clusters. Here we review our main results and stress the power, but also the limitations of the CMD modeling process. We also discuss the perspectives opened by Gemini and SOAR telescopes.