  Real-space picture of electron recollision with the parent ion guides our
understanding of the highly nonlinear response of atoms and molecules to
intense low-frequency laser fields. It is also among several leading
contestants for the dominant mechanism of high harmonic generation (HHG) in
solids, where it is typically viewed in the momentum space, as the
recombination of the conduction band electron with the valence band hole,
competing with another HHG mechanism, the strong-field driven Bloch
oscillations. In this work, we use numerical simulations to directly test and
confirm the real-space recollision picture as the key mechanism of HHG in
solids. Our tests take advantage of the well-known characteristic features in
the molecular harmonic spectra, associated with the real-space structure of the
molecular ion. We show the emergence of analogous spectral features when
similar real-space structures are present in the periodic potential of the
solid-state lattice. This work demonstrates the capability of HHG imaging of
spatial structures of a unit cell in solids.
