LED-Based Photometric Stereo-Imaging Employing Frequency-Division Multiple Access

Herrnsdorf, Johannes; McKendry, Jonathan J. D.; Stonehouse, Mark; Broadbent, Laurence; Wright, Glynn C.; Dawson, Martin D.; Strain, Michael J.

doi:10.1109/ipcon.2018.8527181

Cited by 3 publications

(1 citation statement)

References 8 publications

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“…As illustrated in Figure 6, photometric stereo imaging relies on illumination from different directions, where the camera resolves the differences in surface shading according to each illumination angle. By modulating the corner LEDs with suitable orthogonal multiple access carrier signals, photometric stereo-imaging can be made robust to background illumination from other light sources or the display itself [17].…”

Section: Resultsmentioning

confidence: 99%

44‐1: Invited Paper: Micro‐LEDs for Technological Convergence between Displays, Optical Communications, and Sensing and Imaging Systems

Dawson

Herrnsdorf

Xie

et al. 2020

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Section: Resultsmentioning

confidence: 99%

44‐1: Invited Paper: Micro‐LEDs for Technological Convergence between Displays, Optical Communications, and Sensing and Imaging Systems

Dawson

Herrnsdorf

Xie

et al. 2020

Symp Digest of Tech Papers

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Pseudo-Passive Time-of-Flight Imaging: Simultaneous Illumination, Communication, and 3D Sensing

et al. 2022

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3D Time-of-Flight (ToF) cameras have recently received a lot of attention due to their wide range of applications. Despite remarkable advancements in ToF imaging, state-of-theart ToF cameras are still afflicted by the power hungriness of their illumination sources. To tackle this problem, we exploited existing lighting infrastructure, that ensures the ubiquitous presence of modulated light sources in indoor spaces, which serve as opportunity illuminators. We explored the bistatic geometry for passive imaging using the pulse-based ToF approach. Our work is inspired by the recently introduced visible light communication (VLC) or light-fidelity (Li-Fi) infrastructure. VLC allows the infrastructure to provide indoor simultaneous illumination, communication, and sensing (SICS). To this end, we designed a bistatic geometry for the purpose of attaining passive 3D imaging. Such capabilities are achieved by exploiting the pulse shape of the autocorrelation function of real optical signals generated by VLC/Li-Fi modules (e. g., OpenVLC and LiFiMAX). We demonstrated passive imaging by means of matched filtering. In this work, we also studied different sampling strategies in the time shift domain, including uniform, random, and sparse rulers, which is another step forward towards preserving high depth accuracy with a minimal number of measurements. The proposed methodology achieved successful depth reconstruction with negligible rootmean-square-error (RMSE) for the low signal-to-noise ratio (SNR) of the measurements. Parametric models such as Gaussian and sum-of-sines are used to characterize the cross-correlation functions and allow for robust parametric depth retrieval from a few measurements. Moreover, we attained 20 mm worst-case error for a target at 25 cm. The experiment proved that the bistatic passive depth reconstruction is feasible.

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Pseudo-Passive Indoor ToF Sensing exploiting Visible Light Communication Sources

2021

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The need for active illumination is one of the fundamental downsides of state-of-the-art Time-of-Flight (ToF) cameras and translates into large power consumption as compared to passive imaging modalities. Recently, developments in visible light communications (VLC) have allowed the lighting infrastructure to provide both illumination and communication services in indoor environments. In this paper, we propose exploiting visible light sources as opportunity illuminators for indoor ToF sensing. This allows for drastically reducing the power consumption of the ToF camera, as the need for illumination modules is eliminated. We study the feasibility of this idea using an off-the-shelf VLC module, model the emitted light signal, and study its autocorrelation properties. We show that the prominence of two dominant frequencies, arising from the underlying clock signal and coding scheme, enables CW-ToF operation. Simulations carried out using real signals from the VLC module showed successful depth estimation, up to an offset, using standard methods for CW-ToF depth estimation such as the four-phases algorithm.

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LED-Based Photometric Stereo-Imaging Employing Frequency-Division Multiple Access

Abstract: We present a photometric stereo-imaging approach based on illumination with light-emitting diodes (LEDs) from different angles where the LEDs are sinusoidally modulated and do not require synchronization with each other or with the camera.

Cited by 3 publications

References 8 publications

44‐1: Invited Paper: Micro‐LEDs for Technological Convergence between Displays, Optical Communications, and Sensing and Imaging Systems

44‐1: Invited Paper: Micro‐LEDs for Technological Convergence between Displays, Optical Communications, and Sensing and Imaging Systems

Pseudo-Passive Time-of-Flight Imaging: Simultaneous Illumination, Communication, and 3D Sensing

Pseudo-Passive Indoor ToF Sensing exploiting Visible Light Communication Sources

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