Development of a modular, high-speed plenoptic-camera for 3D flow-measurement

Tan, Zu Puayen; Johnson, Kyle; Clifford, Christopher J.; Thurow, Brian S.

doi:10.1364/oe.27.013400

Cited by 26 publications

(10 citation statements)

References 34 publications

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“…However, for the larger time interval Δt 2 , the estimated particle displacement is significantly different from the actual streamline. From this perspective, prior knowledge of the similar test flow achieved by the computational fluid dynamics (CFD) [49][50][51] or other experimental flow diagnosis techniques [52][53][54][55] is required, which helps to understand the unsteady flow characteristics and determine the upper limit of the time interval (Δt up ) for LF-PIV recordings. The lower limit of the time interval should consider the limitation of the imaging resolution and ensure that the particle motions can be resolved by the LF camera.…”

Section: Selection Of Optimum Cross-correlation Parameters 31 Time In...mentioning

confidence: 99%

Approach to select optimal cross-correlation parameters for light field particle image velocimetry

Zhu

Hossain

et al. 2022

Physics of Fluids

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The light field particle image velocimetry (LF-PIV) has shown a great potential for three-dimensional (3D) flow measurement in space-constrained applications. Usually, the parameters of the cross-correlation calculation in the LF-PIV are chosen based on empirical analysis or introduced from conventional planar PIV, which lowers the accuracy of 3D velocity field measurement. This study presents an approach to selecting optimal parameters of the cross-correlation calculation and thereby offers systematic guidelines for experiments. The selection criterion of the interrogation volume size is studied based on the analysis of the valid detection probability of the correlation peak. The optimal seeding concentration and the size of tracer particles are then explored through synthetic Gaussian vortex field reconstruction. The optimized parameters are employed in a cylinder wake flow measurement in a confined channel. A comparative study is conducted between the LF-PIV and a planar PIV system. Results indicate that the LF-PIV along with the optimized parameters can measure the 3D flow velocity of the cylinder wakes accurately. It has been observed that the mean and max errors of velocity decrease by 32.6% and 18.8%, respectively compared to the related LF-PIV techniques without consideration of optimal parameters. Therefore, it is suggested that the optimized cross-correlation parameters in the LF-PIV can improve the accuracy of 3D flow measurement.

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Section: Selection Of Optimum Cross-correlation Parameters 31 Time In...mentioning

confidence: 99%

Approach to select optimal cross-correlation parameters for light field particle image velocimetry

Zhu

Hossain

et al. 2022

Physics of Fluids

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“…Reprinted, with permission, from [27]. (D) Relayed MLA used on a high-speed camera [29,30]. Adapted from [29] and [30].…”

Section: Principles and Hardware Of Lf Imagingmentioning

confidence: 99%

Section: Principles and Hardware Of Lf Imagingmentioning

confidence: 99%

Perspective on the development and application of light-field cameras in flow diagnostics

Tan

Thurow

2021

Meas. Sci. Technol.

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Multi-camera flow diagnostics have made large gains in recent years in the field of three-dimensional and multi-physics measurements. However, cost, complexity and optical access pose challenges that place multi-camera techniques out of reach for many labs. In that context, light-field (LF) imaging represents an alternative approach that can potentially alleviate some of these challenges. LF flow diagnostics is a branch of measurement techniques introduced within the last decade that are based on a plenoptic camera's unique ability to capture three-dimensional and multi-spectral data via a single objective lens and image sensor-albeit at reduced lateral resolutions and depth-to-lateral uncertainty ratios of 3-10 due to limited parallax angle. Thus far, LF flow diagnostics have successfully achieved significant camera-reduction alongside other performance improvements in 3D flow velocimetry, 3D particle tracking, 3D scalar-field tomography, micro-fluidic velocimetry and multi-spectral imaging, as well as early demonstrations of single-camera multi-physics measurements for applications such as 3D fluid-structure interactions. Here, we discuss the state of development in LF flow diagnostics, highlight on-going challenges, and project potential advancements in the near future.

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“…1 is an inverted schematic of the arrangement used in this work, with the mirror and wing assembly contained in a 1.2 m × 1.2 m × 1.2 m acrylic water tank and an encoder incorporated to track the mirror's azimuth angle. The plenoptic camera assembly is composed of a 4096 × 2304 pixel resolution Phantom VEO 4k 990L camera and a Modular Plenoptic Adaptor (Tan et al (2019)) that houses a 471 × 362 microlens array, an optical relay system, as well as a 200 mm main imaging lens. The calibration plate was held in place by a mounting wing consisting of evenly spaced holes to position the plate at 10.16 mm increments in the depth direction.…”

Section: Setupmentioning

confidence: 99%

Development and Uncertainty Characterization of Rotating 3D Velocimetry using a Single Plenoptic Camera

Moaven¹,

Gururaj²,

Tan³

et al. 2021

ISPIV21

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Rotating 3D velocimetry (R3DV) is a single-camera PIV technique designed to track the evolution of flow over a rotor in the rotating reference frame. A high-speed (stationary) plenoptic camera capable of 3D imaging captures the motion of particles within the volume of interest through a revolving mirror from the central hub of a hydrodynamic rotor facility, a by-product being an undesired image rotation. R3DV employs a calibration method adapted for rotation such that during MART reconstruction, voxels are mapped to pixel coordinates based on the mirror’s instantaneous azimuthal position. Interpolation of calibration polynomial coefficients using a fitted Fourier series is performed to bypass the need to physically calibrate volumes corresponding to each fine azimuth angle. Reprojection error associated with calibration is calculated on average to be less than 0.6 of a pixel. Experimental uncertainty of cross-correlated 3D/3C vector fields is quantified by comparing vectors obtained from imaging quiescent flow via a rotating mirror to an idealized model based purely on rotational kinematics. The uncertainty shows no dependency on azimuth angle while amounting to approximately less than 0.21 voxels per timestep in the in-plane directions and correspondingly 1.7 voxels in the radial direction, both comparable to previously established uncertainty estimations for single-camera plenoptic PIV.

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Development of a modular, high-speed plenoptic-camera for 3D flow-measurement

Cited by 26 publications

References 34 publications

Approach to select optimal cross-correlation parameters for light field particle image velocimetry

Approach to select optimal cross-correlation parameters for light field particle image velocimetry

Perspective on the development and application of light-field cameras in flow diagnostics

Development and Uncertainty Characterization of Rotating 3D Velocimetry using a Single Plenoptic Camera

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