Non-line-of-sight imaging using phasor-field virtual wave optics

Area of Science:

• Optics and Photonics
• Computational Imaging
• Wave Physics

Background:

• Non-line-of-sight (NLOS) imaging enables observation of occluded objects via indirect diffuse reflections.
• Current NLOS methods are limited by assumptions of single scattering, ideal reflectance, and scene occlusions.

Purpose of the Study:

• To develop a novel NLOS imaging framework that overcomes practical limitations of existing methods.
• To formulate NLOS imaging as a diffractive wave propagation problem, analogous to line-of-sight imaging.

Main Methods:

• Introduction of a virtual wave field, the 'phasor field', to model NLOS scenes.
• Application of mathematical operators for wave propagation, specifically the Rayleigh-Sommerfeld diffraction integral, to time-of-flight data.
• Development of three imaging algorithms based on established line-of-sight imaging principles.

Main Results:

• Demonstration of NLOS imaging of complex scenes with multiple scattering, ambient light, and occlusions.
• Successful imaging across arbitrary materials and large depth ranges.
• The method effectively handles challenging conditions without explicit inversion of light-transport models.

Conclusions:

• The proposed wave propagation approach provides a new class of NLOS imaging algorithms.
• This method enhances practical usability and broadens the application scope of NLOS imaging beyond laboratory settings.