  Depth perception is paramount to tackle real-world problems, ranging from
autonomous driving to consumer applications. For the latter, depth estimation
from a single image represents the most versatile solution, since a standard
camera is available on almost any handheld device. Nonetheless, two main issues
limit its practical deployment: i) the low reliability when deployed
in-the-wild and ii) the demanding resource requirements to achieve real-time
performance, often not compatible with such devices. Therefore, in this paper,
we deeply investigate these issues showing how they are both addressable
adopting appropriate network design and training strategies -- also outlining
how to map the resulting networks on handheld devices to achieve real-time
performance. Our thorough evaluation highlights the ability of such fast
networks to generalize well to new environments, a crucial feature required to
tackle the extremely varied contexts faced in real applications. Indeed, to
further support this evidence, we report experimental results concerning
real-time depth-aware augmented reality and image blurring with smartphones
in-the-wild.
