Event-based Motion-Robust Accurate Shape Estimation for Mixed
  Reflectance Scenes
Aniket Dashpute Jiazhang Wang James Taylor Oliver Cossairt Ashok Veeraraghavan Florian Willomitzer
Event-based structured light systems have recently been introduced as an
exciting alternative to conventional frame-based triangulation systems for the
3D measurements of diffuse surfaces. Important benefits include the fast
capture speed and the high dynamic range provided by the event camera - albeit
at the cost of lower data quality. So far, both low-accuracy event-based as
well as high-accuracy frame-based 3D imaging systems are tailored to a specific
surface type, such as diffuse or specular, and can not be used for a broader
class of object surfaces ("mixed reflectance scenes"). In this paper, we
present a novel event-based structured light system that enables fast 3D
imaging of mixed reflectance scenes with high accuracy. On the captured events,
we use epipolar constraints that intrinsically enable decomposing the measured
reflections into diffuse, two-bounce specular, and other multi-bounce
reflections. The diffuse objects in the scene are reconstructed using
triangulation. Eventually, the reconstructed diffuse scene parts are used as a
"display" to evaluate the specular scene parts via deflectometry. This novel
procedure allows us to use the entire scene as a virtual screen, using only a
scanning laser and an event camera. The resulting system achieves fast and
motion-robust (14Hz) reconstructions of mixed reflectance scenes with < 500
$\mu$m accuracy. Moreover, we introduce a "superfast" capture mode (250Hz) for
the 3D measurement of diffuse scenes.