(a) Temporal interaction of light and material. A correlation
image sensor correlates the reference signal with a mixture of
direct (black) and indirect (green and red) components, as indicated in blue.
(b) Visually similar but structurally distinct material samples in RGB. Top: paper; bottom: wax.
(c) After depth normalization, the raw measurements of materials
in (b) become separable.
Abstract
We propose a material classification method using raw time-of-flight
(ToF) measurements. ToF cameras capture the correlation between a
reference signal and the temporal response of material to incident
illumination. Such measurements encode unique signatures of the
material, i.e. the degree of subsurface scattering inside a volume.
Subsequently, it offers an orthogonal domain of feature representation
compared to conventional spatial and angular reflectance-based
approaches. We demonstrate the effectiveness, robustness, and efficiency
of our method through experiments and comparisons of real-world
materials.
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