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Rajshekhar Gannavarpu

Cette personne a quitté l’EPFL

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Publications associées (22)

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Phase Gradient Estimation Techniques in Fringe Analysis

Rajshekhar Gannavarpu

The thesis introduces novel techniques in the field of fringe analysis for direct estimation of phase gradients or derivatives. A pseudo Wigner-Ville distribution based method is proposed to reliably estimate the phase derivatives from a single fringe patt ...

EPFL2012

Fringe demodulation using the two-dimensional phase differencing operator

Pramod Rastogi, Rajshekhar Gannavarpu

The Letter proposes a method for phase estimation from a fringe pattern. The proposed method relies on a parametric approach where the phase is locally approximated as a two-dimensional (2D) polynomial, with the ensuing polynomial coefficients as the respe ...

Optical Society of America2012

Estimation of phase derivative using adaptive window spectrogram

Pramod Rastogi, Sai Siva Gorthi, Rajshekhar Gannavarpu

The paper introduces an adaptive-window-spectrogram-based method to directly estimate the phase derivative from a single fringe pattern. The proposed method relies on estimating the phase derivative using spectrogram peak detection for a set of different w ...

2010

Estimation of dynamically varying displacement derivatives using fringe projection technique

Pramod Rastogi, Sai Siva Gorthi, Rajshekhar Gannavarpu

This paper presents a pseudo Wigner–Ville-distribution-based method in fringe projection for analyzing temporal behavior of the displacement derivative for a continuously deformed object. In the proposed method, a computer generated fringe pattern is proje ...

Optical Society of America2011

Estimation of Phase in Fringe Projection Technique Using High-order Instantaneous Moments Based Method

Pramod Rastogi, Sai Siva Gorthi, Rajshekhar Gannavarpu

For three-dimensional (3D) shape measurement using fringe projection techniques, the information about the 3D shape of an object is encoded in the phase of a recorded fringe pattern. The paper proposes a high-order instantaneous moments based method to est ...

AIP Conf. Proc.2010

Estimation of displacement derivatives in digital holographic interferometry using a two-dimensional space-frequency distribution

Pramod Rastogi, Sai Siva Gorthi, Rajshekhar Gannavarpu

The paper introduces a two-dimensional space-frequency distribution based method to directly obtain the unwrapped estimate of the phase derivative which corresponds to strain in digital holographic interferometry. In the proposed method, a two-dimensional ...

Optical Society of America2010

Three dimensional shape measurement using high-order instantaneous moments based fringe projection method

Pramod Rastogi, Sai Siva Gorthi, Rajshekhar Gannavarpu

Fringe projection techniques are popular tools for three-dimensional shape measurement in optical metrology. In these techniques, the information about the shape or the surface profile of an object is usually encoded in the phase of a recorded fringe patte ...

2011

Investigations to realize a computationally efficient implementation of the high-order instantaneous moments based fringe analysis method

Pramod Rastogi, Sai Siva Gorthi, Rajshekhar Gannavarpu

Recently, a high-order instantaneous moments (HIM)-operator- based method was proposed for accurate phase estimation in digital holographic interferometry. The method relies on piece-wise polynomial approximation of phase and subsequent evaluation of the p ...

2010

Detection of defects from fringe patterns using a pseudo-Wigner-Ville distribution based method

Pramod Rastogi, Sai Siva Gorthi, Rajshekhar Gannavarpu

The paper presents a method to identify defects from fringe patterns. In the proposed method, the phase derivatives are computed from a fringe pattern using the two-dimensional Pseudo-Wigner–Ville distribution. Since the phase derivative varies rapidly in ...

Elsevier2012

Simultaneous multidimensional deformation measurements using digital holographic moiré

Pramod Rastogi, Sai Siva Gorthi, Rajshekhar Gannavarpu

This paper proposes an elegant technique for the simultaneous measurement of in-plane and out-of-plane displacements of a deformed object in digital holographic interferometry. The measurement relies on simultaneously illuminating the object from multiple ...

Optical Society of America2011

Estimation of multiple phases from a single fringe pattern in digital holographic interferometry

Pramod Rastogi, Sai Siva Gorthi, Rajshekhar Gannavarpu

Simultaneous measurement of multidimensional displacements using digital holographic interferometry involves multi-directional illumination of the deformed object and requires the reliable estimation of the resulting multiple interference phase distributio ...

Optical Society of America2012

Simultaneous measurement of in-plane and out-of-plane displacement derivatives using dual-wavelength digital holographic interferometry

Pramod Rastogi, Sai Siva Gorthi, Rajshekhar Gannavarpu

The paper introduces a method for simultaneously measuring the in-plane and out-of-plane displacement derivatives of a deformed object in digital holographic interferometry. In the proposed method, lasers of different wavelengths are used to simultaneously ...

Optical Society of America2011

Application of complex-lag distributions for estimation of arbitrary order phase derivatives in digital holographic interferometry

Pramod Rastogi, Rajshekhar Gannavarpu

This Letter proposes a method to estimate phase derivatives of arbitrary order in digital holographic interferometry. Based on the desired order, the generalized complex-lag distribution is computed from the reconstructed interference field. Subsequently, ...

Optical Society of America2011

Phase estimation using a state-space approach based method

Pramod Rastogi, Rajshekhar Gannavarpu

The paper demonstrates a phase estimation method in fringe analysis. The proposed method relies on local polynomial phase approximation and subsequent state-space formulation. The polynomial approximation of phase transforms phase extraction into a paramet ...

Elsevier2013

Strain, curvature and twist measurements in digital holographic interferometry using pseudo Wigner-Ville distribution based method

Pramod Rastogi, Sai Siva Gorthi, Rajshekhar Gannavarpu

American Institute of Physics2009

Multiple signal classification technique for phase estimation from a fringe pattern

Pramod Rastogi, Rajshekhar Gannavarpu

The paper introduces a multiple signal classification technique based method for fringe analysis. In the proposed method, the phase of a fringe pattern is locally approximated as a polynomial. The polynomial phase signal is then transformed to obtain signa ...

Optical Society of America2012

Comparative Analysis of Various Single-tone Frequency Estimation Techniques in High-order Instantaneous Moments Based Phase Estimation Method

Pramod Rastogi, Sai Siva Gorthi, Rajshekhar Gannavarpu

For phase estimation in digital holographic interferometry, a high-order instantaneous moments (HIM) based method was recently developed which relies on piecewise polynomial approximation of phase and subsequent evaluation of the polynomial coefficients us ...

AIP Conf. Proc.2010

Rajshekhar Gannavarpu

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Phase Gradient Estimation Techniques in Fringe Analysis

Fringe demodulation using the two-dimensional phase differencing operator

Estimation of phase derivative using adaptive window spectrogram

Estimation of dynamically varying displacement derivatives using fringe projection technique

Estimation of Phase in Fringe Projection Technique Using High-order Instantaneous Moments Based Method

Estimation of displacement derivatives in digital holographic interferometry using a two-dimensional space-frequency distribution

Three dimensional shape measurement using high-order instantaneous moments based fringe projection method

Investigations to realize a computationally efficient implementation of the high-order instantaneous moments based fringe analysis method

Detection of defects from fringe patterns using a pseudo-Wigner-Ville distribution based method

Simultaneous multidimensional deformation measurements using digital holographic moiré

Estimation of multiple phases from a single fringe pattern in digital holographic interferometry

Simultaneous measurement of in-plane and out-of-plane displacement derivatives using dual-wavelength digital holographic interferometry

Application of complex-lag distributions for estimation of arbitrary order phase derivatives in digital holographic interferometry

Phase estimation using a state-space approach based method

Strain, curvature and twist measurements in digital holographic interferometry using pseudo Wigner-Ville distribution based method

Multiple signal classification technique for phase estimation from a fringe pattern

Comparative Analysis of Various Single-tone Frequency Estimation Techniques in High-order Instantaneous Moments Based Phase Estimation Method

Strain estimation in digital holographic interferometry using piecewise polynomial phase approximation based method

Polynomial Wigner-Ville distribution based method for direct phase derivative estimation from optical fringes

Adaptive window Wigner-Ville distribution based method to estimate phase derivative from optical fringes