Two-dimensional Gaussian regression for sub-pixel displacement estimation in particle image velocimetry or particle position estimation in particle tracking velocimetry

Nobach, Holger; Honkanen, Markus

doi:10.1007/s00348-005-0942-3

Cited by 142 publications

(98 citation statements)

References 13 publications

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“…7). Sub-pixeling reduces RMS errors depending on the weight function adopted to estimate the crosscorrelation map (Nobach and Honkanen, 2005). In our case, using an elliptical Gaussian the accuracy increases by roughly a factor of 10.…”

Section: ¡Mage Processing and Expected Errorsmentioning

confidence: 79%

“…5) based on a weighted normalized cross-correlation (CC) between the image content delimited by the Left and Right ASWs centered at the generic matching point (red dot) and the fixed pixel (blue dot) respectively. For WASS, the weight or CC kernel to perform convolution is chosen as an elliptical Gaussian (Nobach and Honkanen, 2005). A CC map, such as that shown in Fig.…”

Section: ¡Mage Processing and Expected Errorsmentioning

confidence: 99%

See 1 more Smart Citation

Offshore stereo measurements of gravity waves

Benetazzo

Fedele

Gallego

et al. 2012

Coastal Engineering

111

104

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Stereo video techniques are effective for estimating the space-time wave dynamics over an area of the ocean. Indeed, a stereo camera view allows retrieval of both spatial and temporal data whose statistical content is richer than that of time series data retrieved from point wave probes. To prove this, we consider an application of the Wave Acquisition Stereo System (WASS) for the analysis of offshore video measurements of gravity waves in the Northern Adriatic Sea. In particular, we deployed WASS at the oceanographic platform Acqua Alta, off the Venice coast, Italy. Three experimental studies were performed, and the overlapping field of view of the acquired stereo images covered an area of approximately 1100 m 2 . Analysis of the WASS measurements show that the sea surface can be accurately estimated in space and time together, yielding associated directional spectra and wave statistics that agree well with theoretical models. From the observed wavenumber-frequency spectrum one can also predict the vertical profile of the current flow underneath the wave surface. Finally, future improvements of WASS and applications are discussed.

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Section: ¡Mage Processing and Expected Errorsmentioning

confidence: 79%

Section: ¡Mage Processing and Expected Errorsmentioning

confidence: 99%

Offshore stereo measurements of gravity waves

Benetazzo

Fedele

Gallego

et al. 2012

Coastal Engineering

111

104

View full text Add to dashboard Cite

show abstract

“…The pixel footprint of the imaged area gives an estimate of WASS resolution on the horizontal plane, which is approximately 40 mm and 20 mm for Acqua Alta and Crimean experiments, respectively. In the epipolar method, the use of a sub-pixel detection algorithm did improve the resolution by a factor 5-10 (see Benetazzo et al 2012, Nobach, H., Honkanen, M., 2005. As regard to vertical resolution, the WASS system is intrinsically a high-resolution system, because the Z-coordinate is a continuous function of both left and right image coordinates as well as internal/external parameters.…”

Section: Wass Deployments and Data Acquisitionmentioning

confidence: 99%

Space–time measurements of oceanic sea states

et al. 2013

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“…A variety of sub-pixel interpolation methods have been proposed in the literature [30,31]. In [32] a sub-pixel interpolation method, which accounts for non-axially orientated, elliptically shaped particle images or correlation peaks, is proposed.…”

Section: Sub-pixel Peak Fittingmentioning

confidence: 99%

“…Simple geometrical analysis of the 2D shape of the bubbles indicated that in the binning modes under investigation the circular shape of bubbles degenerated into elliptical shapes. The general elliptical Gaussian function centered at (Δx, Δy) is defined as follows [32]:…”

Section: Sub-pixel Peak Fittingmentioning

confidence: 99%

Experimentally investigation of the CCD binning option in particle imaging velocimetry measurements of laminar flows

Akselli

Teke

2011

Int. J. Metrol. Qual. Eng.

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Abstract. In this work we present an experimental investigation of the employment usage application of the vertical pixel binning (PB) option for PIV (particle image velocimetry) measurements. The PB option increases the speed of a CCD, at the cost of loosing spatial resolution. Consequently, it is expected that PB will positively impact the dynamic velocity range of the PIV measurements. In order to show the benefit of the CCD PB option in PIV measurements, we have carried out series of microPIV experiments on laminar flows, seeded with 1 µm fluorescent polystyrene microparticles and passing through a 200 µm × 200 µm × 50 000 µm microchannel. The flow images were recorded at normal, 2 × 1, and 3 × 1 vertical PB modes of a monochrome CCD camera. The experimentally obtained velocity profiles were calculated using the ensemble-averaged cross-correlation method and Gaussian sup-pixel interpolation and then compared with theoretically calculated velocity profiles. We found that the error introduced by the PB option did not exceed the inherent uncertainty of the PIV system used. For a particular PIV system CCD camera, using the PB option allowed an increase in the dynamic velocity range of a PIV system by more than a factor of two, without extra investments.

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Two-dimensional Gaussian regression for sub-pixel displacement estimation in particle image velocimetry or particle position estimation in particle tracking velocimetry

Cited by 142 publications

References 13 publications

Offshore stereo measurements of gravity waves

Offshore stereo measurements of gravity waves

Space–time measurements of oceanic sea states

Experimentally investigation of the CCD binning option in particle imaging velocimetry measurements of laminar flows

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