Design of a Single-Lens Freeform-Prism-Based Distortion-Free Stereovision System

Xiaoyu Cui,Yue Zhao,Liqian Wang,Shuo Chen,Kahbin Lim,Yuetian Ren,Tianxing Gong

doi:10.1109/jphot.2019.2924458

Xiaoyu Cui, Yue Zhao + Show 5 more

Open Access

https://doi.org/10.1109/jphot.2019.2924458

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Abstract

Stereo vision can be achieved with a single camera aided by a flat-face prism. However, large optical distortions may be caused by irregular refraction. To mitigate this deficiency and minimize distortion, a new freeform prism design is proposed to replace the flat-face prism. All refracting surfaces of the prism are designed for freeform features, which can process object points at a large depth of field. Differential equations are derived to express the freeform surface, and the Runge–Kutta method is used to numerically solve the differential equations.

Highlights

The single-lens prism-based stereovision (PbS) system can reconstruct a 3D scene
Thereafter, in their pioneering work, by placing a prism in front of a camera lens, Lim et al [8] introduced a method, which assumed that a scene captured by a PbS system would give rise to two images captured by two virtual camera systems [8], [9]
We present a modified virtual camera model as a basis to correct the refractive ray of the flat prism, which can be widely used for stereovision applications

Summary

Introduction

The single-lens prism-based stereovision (PbS) system can reconstruct a 3D scene. Such a system, which uses only one camera, significantly simplifies the integration effort of a stereovision system. This model did not consider the nonlinear distortion caused by the biprism, which limited the shape retrieval accuracy Thereafter, in their pioneering work, by placing a prism in front of a camera lens, Lim et al [8] introduced a method, which assumed that a scene captured by a PbS system would give rise to two images captured by two virtual camera systems [8], [9]. To solve this problem, many image-based [19] or opticalbased [3], [20], [21] methods were proposed by researchers. We believe that our proposed freeform PbS system can acquire undistorted stereo image pairs at a single shot of the camera, and we directly implement the stereo correspondence algorithm without image rectification

Method

The Constraints of Virtual Pinhole Camera

Design the Freeform Surface of the Prism

Experiment

Conclusion