  We demonstrate a photon-sensitive, three-dimensional camera by active
near-infrared illumination and fast time-of-flight gating. It uses pico-second
pump pulses to selectively up-convert the backscattered photons according to
their spatiotemporal modes via sum-frequency generation in a \c{hi}2 nonlinear
crystal, which are then detected by electron-multiplying CCD with photon
sensitive detection. As such, it achieves sub-millimeter depth resolution,
exceptional noise suppression, and high detection sensitivity. Our results show
that it can accurately reconstruct the surface profiles of occluded targets
placed behind highly scattering and lossy obscurants of 14 optical depth (round
trip), using only milliwatt illumination power. This technique may find
applications in biomedical imaging, environmental monitoring, and wide-field
light detection and ranging
