标题: Single View Reflectance Capture using Multiplexed Scattering and Time-of-flight Im [打印本页] 作者: 晃晃 时间: 2011-12-29 08:28 标题: Single View Reflectance Capture using Multiplexed Scattering and Time-of-flight Im Single View Reflectance Capture using Multip***d Scattering and Time-of-flight Imaging
Nikhil Naik Shuang Zhao Andreas Velten Ramesh Raskar Kavita Bala
MIT Media Lab Cornell University
Abstract
This paper introduces the concept of time-of-flight reflectance esti-
mation, and demonstrates a new technique that allows a camera to
rapidly acquire reflectance properties of objects from a single view-
point, over relatively long distances and without encircling equip-
ment. We measure material properties by indirectly illuminating
an object by a laser source, and observing its reflected light indi-
rectly using a time-of-flight camera. The configuration collectively
acquires dense angular, but low spatial sampling, within a limited
solid angle range - all from a single viewpoint. Our ultra-fast imag-
ing approach captures space-time “streak images" that can separate
out different bounces of light based on path length. Entanglements
arise in the streak images mixing signals from multiple paths if they
have the same total path length. We show how reflectances can be
recovered by solving for a linear system of equations and assuming
parametric material models; fitting to lower dimensional reflectance
models enables us to disentangle measurements.
We demonstrate proof-of-concept results of parametric reflectance
models for homogeneous and discretized heterogeneous patches,
both using simulation and experimental hardware. As compared
to lengthy or highly calibrated BRDF acquisition techniques, we
demonstrate a device that can rapidly, on the order of seconds, cap-
ture meaningful reflectance information. We expect hardware ad-
vances to improve the portability and speed of this device.
