Design tool for TOF and SL based 3D cameras

Bouquet, Grégory; Thorstensen, Jostein; Bakke, Kari Anne Hestnes; Risholm, Petter

doi:10.1364/oe.25.027758

Cited by 16 publications

(8 citation statements)

References 14 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Three-dimensional (3D) dynamic reconstruction is an important technique in the field of computer vision that has been widely applied in manufacturing, industrial inspection, human-computer interaction, robotics, augmented reality (AR)/virtual reality (VR), and so on [1,2]. Currently, 3D dynamic reconstruction techniques mainly include time of flight (TOF) [3,4], binocular stereo vision (BSV) [5,6], and structured light (SL) [7,8]. All these techniques have advantages and disadvantages, which are as follows: (1) TOF technique: The TOF technique uses active sensing to capture 3D range data as per-pixel depths [9].…”

Section: Introductionmentioning

confidence: 99%

Single-Shot Structured Light Sensor for 3D Dense and Dynamic Reconstruction

Song

Zhao

2020

Sensors

View full text Add to dashboard Cite

Structured light (SL) has a trade-off between acquisition time and spatial resolution. Temporally coded SL can produce a 3D reconstruction with high density, yet it is not applicable to dynamic reconstruction. On the contrary, spatially coded SL works with a single shot, but it can only achieve sparse reconstruction. This paper aims to achieve accurate 3D dense and dynamic reconstruction at the same time. A speckle-based SL sensor is presented, which consists of two cameras and a diffractive optical element (DOE) projector. The two cameras record images synchronously. First, a speckle pattern was elaborately designed and projected. Second, a high-accuracy calibration method was proposed to calibrate the system; meanwhile, the stereo images were accurately aligned by developing an optimized epipolar rectification algorithm. Then, an improved semi-global matching (SGM) algorithm was proposed to improve the correctness of the stereo matching, through which a high-quality depth map was achieved. Finally, dense point clouds could be recovered from the depth map. The DOE projector was designed with a size of 8 mm × 8 mm. The baseline between stereo cameras was controlled to be below 50 mm. Experimental results validated the effectiveness of the proposed algorithm. Compared with some other single-shot 3D systems, our system displayed a better performance. At close range, such as 0.4 m, our system could achieve submillimeter accuracy.

show abstract

Section: Introductionmentioning

confidence: 99%

Single-Shot Structured Light Sensor for 3D Dense and Dynamic Reconstruction

Song

Zhao

2020

Sensors

View full text Add to dashboard Cite

show abstract

“…The total signal is determined as Is=Ia+Ib. The phase uncertainty is dependent on the image noise, primarily shot-noise of each of the phase-shifted images, and can be shown to be [22]:σϕw(x,y)= Ia(x,y)+2Ib(x,y)Ia(x,y)…”

Section: Methodsmentioning

confidence: 99%

“…Gray-codes are often used to phase-unwrap the phase-maps from high-frequency phase-shifted sinusoidal patterns [21]. The depth-precision of such systems are limited by the number of codes that can be reliably segmented [22]. With increasing turbidity, the boundary between illuminated and non-illuminated areas are blurred and an accurate segmentation is difficult [23].…”

Section: Introductionmentioning

confidence: 99%

Adaptive Structured Light with Scatter Correction for High-Precision Underwater 3D Measurements

Risholm

Kirkhus

Thielemann

et al. 2019

Sensors

Self Cite

View full text Add to dashboard Cite

High-precision underwater 3D cameras are required to automate many of the traditional subsea inspection, maintenance and repair (IMR) operations. In this paper we introduce a novel multi-frequency phase stepping (structured light) method for high-precision 3D estimation even in turbid water. We introduce an adaptive phase-unwrapping procedure which uses the phase-uncertainty to determine the highest frequency that can be reliably unwrapped. Light scattering adversely affects the phase estimate. We propose to remove the effect of forward scatter with an unsharp filter and a model-based method to remove the backscatter effect. Tests in varying turbidity show that the scatter correction removes the adverse effect of scatter on the phase estimates. The adaptive frequency unwrapping with scatter correction results in images with higher accuracy and precision and less phase unwrap errors than the Gray-Code Phase Stepping (GCPS) approach.

show abstract

“…In a previous work [24], we have developed theory to predict the precision obtainable from a TOF system.…”

Section: A Theoretical Depth Resolutionmentioning

confidence: 99%

Real-time super-resolved 3D in turbid water using a fast range-gated CMOS camera

Risholm¹,

Thorstensen²,

Thielemann³

et al. 2018

Appl. Opt.

Self Cite

View full text Add to dashboard Cite

We present a range-gated camera system designed for real-time (10 Hz) 3D estimation underwater. The system uses a fast-shutter CMOS sensor (1280×1024) customized to facilitate gating with 1.67 ns (18.8 cm in water) delay steps relative to the triggering of a solid-state actively Q-switched 532 nm laser. A depth estimation algorithm has been carefully designed to handle the effects of light scattering in water, i.e., forward and backward scattering. The raw range-gated signal is carefully filtered to reduce noise while preserving the signal even in the presence of unwanted backscatter. The resulting signal is proportional to the number of photons that are reflected during a small time unit (range), and objects will show up as peaks in the filtered signal. We present a peak-finding algorithm that is robust to unwanted forward scatter peaks and at the same time can pick out distant peaks that are barely higher than peaks caused by sensor and intensity noise. Super-resolution is achieved by fitting a parabola around the peak, which we show can provide depth precision below 1 cm at high signal levels. We show depth estimation results when scanning a range of 8 m (typically 1-9 m) at 10 Hz. The results are dependent on the water quality. We are capable of estimating depth at distances of over 4.5 attenuation lengths when imaging high albedo targets at low attenuation lengths, and we achieve a depth resolution (σ) ranging from 0.8 to 9 cm, depending on signal level.

show abstract

Design tool for TOF and SL based 3D cameras

Cited by 16 publications

References 14 publications

Single-Shot Structured Light Sensor for 3D Dense and Dynamic Reconstruction

Single-Shot Structured Light Sensor for 3D Dense and Dynamic Reconstruction

Adaptive Structured Light with Scatter Correction for High-Precision Underwater 3D Measurements

Real-time super-resolved 3D in turbid water using a fast range-gated CMOS camera

Contact Info

Product

Resources

About