A Calibration Method for Indirect Time-of-Flight Cameras to Eliminate Internal Scattering Interference

TL;DR

This paper introduces a calibration method for indirect Time-of-Flight cameras that models internal scattering interference using three parameters, significantly improving depth measurement accuracy without hardware changes.

Contribution

The paper presents a novel calibration model with interpretable parameters to compensate for internal scattering in iToF cameras, enhancing depth accuracy in complex scenarios.

Findings

Effective scattering compensation improves depth accuracy

Calibration parameters correlate with physical optical effects

Method enhances robustness across diverse environments

Abstract

In-camera light scattering is a typical form of non-systematic interference in indirect Time-of-Flight (iToF) cameras, primarily caused by multiple reflections and optical path variations within the camera body. This effect can significantly reduce the accuracy of background depth measurements. To address this issue, this paper proposes a calibration-based model derived from real measurement data, introducing three physically interpretable calibration parameters: a normal-exposure amplitude influence coefficient, an overexposure amplitude influence coefficient, and a scattering phase shift coefficient. These parameters are used to describe the effects of foreground size, exposure conditions, and optical path differences on scattering interference. Experimental results show that the depth values calculated using the calibrated parameters can effectively compensate for scattering-induced errors, significantly improving background depth recovery in scenarios with complex foreground geometries and varying illumination conditions. This approach provides a practical, low-cost solution for iToF systems, requiring no complex hardware modifications, and can substantially enhance measurement accuracy and robustness across a wide range of real-world applications.