3D Least Squares Matching (LSM) calculate an average velocity of several particles in a small subsection of the measurement volume. The reconstruction methods first require that we generate a digital volume – the so-called voxel space – which contains the gray level values obtained from the multiple camera views of the illuminated particles in the measurement volume.
The second step is to find the average velocity in small subsections (cuboids) of the voxel space which are similar to the interrogation areas in planar PIV. The velocity is then calculated using the particle motion between two consecutive reconstructed voxel spaces from the consecutive camera images.
The 3D LSM is an iterative method that calculates not only the displacement of a cuboid, but also the rotations, shear, stretching and scaling of the two consecutive gray value distributions. The procedure then uses the two cuboids from the two consecutive voxel spaces and iteratively adjusts them by translation, rotation, shearing and scaling until the best match between the two time steps is found.
3D Least Squares Matching is the most advanced tool for volumetric data analysis since both the full field velocity information and the velocity gradient matrix are provided as a result of the analysis process. Unlike the cross correlation technique where gradients are derived in a second step, 3D LSM yields these results directly. This advantage not only improves the quality of the velocity gradient matrix, but also enhances the subsequent post processing of the data to fully understand the physics of the phenomena under investigation.
Solution Sheet
Learn more about how Volumetric Velocimetry systems can help you solve your 3D flow testing challenges.
Measurement Principle
Learn more about the techniques available for Volumetric Velocimetry.
Components
PIV lasers for 10-200 Hz Systems
PIV lasers for 10-200 Hz Systems
Double Frame Cameras
Double Frame Cameras
TR-PIV lasers for 0.5-20 kHz systems
TR-PIV lasers for 0.5-20 kHz systems
Time Resolved Cameras
Time Resolved Cameras
Synchronizers
Synchronizers
Volumetric Illumination
Volumetric Illumination
PCs and Workstations
PCs and Workstations
Seeding Generators
Seeding Generators
Seeding Materials
Seeding Materials
Light Guiding Arms
Light Guiding Arms
ActiveTarget – for simplified and automated spatial camera calibrations
ActiveTarget – for simplified and automated spatial camera calibrations
Traverse Systems
Traverse Systems
Laser safety
Laser safety
DynamicStudio for Planar and Tomo PIV and PTV
DynamicStudio for Planar and Tomo PIV and PTV
Download Library
TITLE
DOWNLOAD FILE
DOWNLOAD FILE
FILETITLE
AUTHOR(S)
YEAR
DOWNLOAD FILE
AUTHOR(S)
M.Beczek, M.Ryżak, A.Sochan, C.Polakowski, D.Hess, A.Bieganowski
YEAR
2020
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Science DirectTITLE
Volumetric Calibration Refinement using masked back projection and image correlation superposition
AUTHOR(S)
Christoph Brücker, David Hess, Bo B. Watz
YEAR
2018
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PDFTITLE
Rapid 3D velocity reconstruction from volumetric particle fields via re-slicing and recombination
AUTHOR(S)
Christoph Brücker, Thomas Nonn
YEAR
2012
DOWNLOAD FILE
PDFAUTHOR(S)
J. Kitzhofer, P. Westfeld, O. Pust, T. Nonn, H. G. Maas, C. Brücker
YEAR
2010
DOWNLOAD FILE
PDFAUTHOR(S)
Patrick Westfeld, Hans-Gerd Maas, Oliver Pust, Jens Kitzhofer, Christoph Brücker
YEAR
2010
