  We present three-dimensional radiative transfer calculations for the ejecta
from a neutron star merger that include line-by-line opacities for tens of
millions of bound-bound transitions, composition from an r-process nuclear
network, and time-dependent thermalization of decay products from individual
$\alpha$ and $\beta^-$ decay reactions. In contrast to expansion opacities and
other wavelength-binned treatments, a line-by-line treatment enables us include
fluorescence effects and associate spectral features with the emitting and
absorbing lines of individual elements. We find variations in the synthetic
observables with both the polar and azimuthal viewing angles. The spectra
exhibit blended features with strong interactions by Ce III, Sr II, Y II, and
Zr II that vary with time and viewing direction. We demonstrate the importance
of wavelength-calibration of atomic data using a model with calibrated Sr, Y,
and Zr data, and find major differences in the resulting spectra, including a
better agreement with AT2017gfo. The synthetic spectra for near-polar
inclination show a feature at around 8000 A, similar to AT2017gfo. However,
they evolve on a more rapid timescale, likely due to the low ejecta mass (0.005
M$_\odot$) as we take into account only the early ejecta. The comparatively
featureless spectra for equatorial observers gives a tentative prediction that
future observations of edge-on kilonovae will appear substantially different
from AT2017gfo. We also show that 1D models obtained by spherically averaging
the 3D ejecta lead to dramatically different direction-integrated luminosities
and spectra compared to full 3D calculations.
