  We present a framework to build realistic mock spectroscopic observations for
state-of-the-art hydrodynamical simulations, using high spectral resolution
stellar population models and full radiative transfer treatment with SKIRT. As
a first application we generate stellar continuum mock observations for the
Auriga cosmological zoom simulations emulating integral-field observations from
the SAMI Galaxy survey. We perform spectral fitting on our synthetic cubes and
compute the resulting rotation velocity ($V_{\rm{rot}}$) and velocity
dispersion within 1$R_{\text{e}}$ ($\sigma_{\text{e}}$) for a sub-set of the
Auriga sample. We find that the kinematics produced by Auriga are in good
agreement with the observations from the SAMI Galaxy survey after taking into
account the effects of dust and the systematics produced by the observation
limitations. We also explore the effects of seeing convolution, inclination,
and attenuation on the line-of-sight velocity distribution. For highly inclined
galaxies, these effects can lead to an artificial decrease in the measured
$V/\sigma$ by nearly a factor two (after inclination correction). We also
demonstrate the utility of our method for high-redshift galaxies by emulating
spatially resolved continuum spectra from the LEGA-C survey and, looking
forward, E-ELT HARMONI. Our framework represents a crucial link between the
ground truth for stellar populations and kinematics in simulations and the
observed stellar continuum observations at low and high redshift.
