Аннотация: We present an efficient approach to model spectra for N-body simulations of galaxy mergers (Horizon GalMer project) using the PEGASE.HR synthetic populations. Using the pre-computed grid of PEGASE.HR simple stellar populations (SSP) spectra and/or colours, as well as the kinematics of the particles on the line of sight, we are able to make on-the-fly computation of spectra and/or colours for any region of the simulated galaxies as seen from any direction.