Large-scale surveys provide new constraints on the structure and evolution of the Milky Way. The population synthesis approach is a useful tool to interpret such data sets and to test scenarios of evolution of the Galaxy. New constraints on Galactic parameters have been obtained from the Besançon model of population synthesis, in particular in the inner regions, thanks to near-infrared surveys less affected by interstellar extinction than the optical ones. We present here a few preliminary comparisons between observed and simulated distributions of proper motions in the direction of the Galactic bulge. Next we discuss how bulge stars can be observed and separated from other populations with the RAVE and Gaia surveys.