Dr. Wansong Li Profile

Dr. Wansong Li

at Vereinigte Elektronik-Werkstätten GmbH (VEW)

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Author

Publications (15)

Proceedings Article | 18 August 2014 Paper

Measuring deformations with deflectometry

Wansong Li, Philipp Huke, Jan Burke, Christoph von Kopylow, Ralf Bergmann

Proceedings Volume 9203, 92030F (2014) https://doi.org/10.1117/12.2063446

KEYWORDS: Mirrors, Deflectometry, Cameras, Calibration, Phase measurement, Fringe analysis, Monochromatic aberrations, Reflectivity, Actuators, Error analysis

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Proceedings Article | 13 September 2012 Paper

Absolute optical surface measurement with deflectometry

Wansong Li, Marc Sandner, Achim Gesierich, Jan Burke

Proceedings Volume 8494, 84940G (2012) https://doi.org/10.1117/12.928690

KEYWORDS: Deflectometry, Mirrors, Sensors, Cameras, Confocal microscopy, Distance measurement, Error analysis, Data modeling, Optical testing, 3D metrology

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Proceedings Article | 10 September 2004 Paper

High-resolution 3D shape measurement on specular surfaces by fringe reflection

Thorsten Bothe, Wansong Li, Christoph von Kopylow, Werner Juptner

Proceedings Volume 5457, (2004) https://doi.org/10.1117/12.545987

KEYWORDS: Reflection, Cameras, 3D metrology, Mirrors, Calibration, Particles, Image resolution, Imaging systems, Inspection, Error analysis

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Proceedings Article | 10 September 2004 Paper

Evaluation methods for gradient measurement techniques

Wansong Li, Thorsten Bothe, Christoph von Kopylow, Werner Juptner

Proceedings Volume 5457, (2004) https://doi.org/10.1117/12.546002

KEYWORDS: Shearography, 3D metrology, Fourier transforms, Reflection, Feature extraction, Data integration, Optical metrology, Wavefront sensors, Sensors, Data processing

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Proceedings Article | 30 May 2003 Paper

Applications of inverse pattern projection

Wansong Li, Thorsten Bothe, Michael Kalms, Christoph von Kopylow, Werner Jueptner

Proceedings Volume 5144, (2003) https://doi.org/10.1117/12.508367

KEYWORDS: Cameras, Modulation, Phase shift keying, Projection systems, Inspection, Augmented reality, 3D metrology, Phase measurement, Image processing, Phase shifting

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Fast and robust 3D quality control as well as fast deformation measurement is of particular importance for industrial inspection. Additionally a direct response about measured properties is desired. Therefore, robust optical techniques are needed which use as few images as possible for measurement and visualize results in an efficient way. One promising technique for this aim is the inverse pattern projection which has the following advantages: The technique codes the information of a preceding measurement into the projected inverse pattern. Thus, it is possible to do differential measurements using only one camera frame for each state. Additionally, the results are optimized straight fringes for sampling which are independent of the object curvature. The hardware needs are low as just a programmable projector and a standard camera are necessary. The basic idea of inverse pattern projection, necessary algorithms and found optimizations are demonstrated, roughly. Evaluation techniques were found to preserve a high quality phase measurement under imperfect conditions. The different application fields can be sorted out by the type of pattern used for inverse projection. We select two main topics for presentation. One is the incremental (one image per state) deformation measurement which is a promising technique for high speed deformation measurements. A video series of a wavering flag with projected inverse pattern was evaluated to show the complete deformation series. The other application is the optical feature marking (augmented reality) that allows to map any measured result directly onto the object under investigation. Any properties can be visualized directly on the object’s surface which makes inspections easier than with use of a separated indicating device. The general ability to straighten any kind of information on 3D surfaces is shown while preserving an exact mapping of camera image and object parts. In many cases this supersedes an additional monitor to view results and allows an operator to investigate results on the object, directly.

Proceedings Article | 27 May 2003 Paper

Object-adapted inverse pattern projection: generation, evaluation, and applications

Thorsten Bothe, Wansong Li, Christoph von Kopylow, Werner Juptner

Proceedings Volume 4933, (2003) https://doi.org/10.1117/12.516653

KEYWORDS: Cameras, Augmented reality, Inspection, Projection systems, 3D metrology, Phase measurement, Image processing, Visualization, Modulation, Video

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Fast and robust 3D quality control as well as fast deformation measurement is of particular importance for industrial inspection. Additionally a direct response about measured properties is desired. Therefore, robust optical techniques are needed which use as few images as possible for measurement and visualize results in an efficient way. One promising technique for this aim is the inverse pattern projection which has the following advantages: The technique codes the information of a preceding measurement into the projected inverse pattern. Thus, it is possible to do differential measurements using only one camera frame for each state. Additionally, the results are optimized straight fringes for sampling which are independent of the object curvature. The ability to use any image for inverse projection enables the use for augmented reality, i.e. any properties can be visualized directly on the object's surface which makes inspections easier than with use of a separated indicating device. The hardware needs are low as just a programmable projector and a standard camera are necessary. The basic idea of inverse pattern projection, necessary algorithms ane found optimizations are demonstrated, roughly. Evaluation techniques were found to preserve a high quality phase measurement under imperfect conditions. The different application fields can be sorted out by the type of pattern used for inverse projection. We select two main topics for presentation. One is the incremental (one image per state) deformation measurement which is a promising technique for high speed deformation measurements. A video series of a wavering flag with projected inverse pattern was evaluated to show the complete deformation series. The other application is the optical feature marking (augmented reality) that allows to map any measured result directly onto the object under investigation. The general ability to straighten any kind of information on 3D surfaces is shown while preserving an exact mapping of camera image and object parts. In many cases this supersedes an additional monitor to view results and allows an operator to investigate results on the object, directly.

SPIE Journal Paper | 1 June 2002

Phase unwrapping algorithm based on phase fitting reliability in structured light projection

Wansong Li, Xianyu Su

OE, Vol. 41, Issue 06, (June 2002) https://doi.org/10.1117/12.10.1117/1.1477439

KEYWORDS: Phase shift keying, Modulation, Reliability, Optical engineering, Error analysis, Floods, Imaging systems, Phase measurement, Fringe analysis, Structured light

SPIE Journal Paper | 1 May 2001

Real-time calibration algorithm for phase shifting in phase-measuring profilometry

Wansong Li, Xianyu Su

OE, Vol. 40, Issue 05, (May 2001) https://doi.org/10.1117/12.10.1117/1.1357195

KEYWORDS: Phase shifts, Modulation, Fringe analysis, Calibration, Phase shifting, Phase shift keying, Bandpass filters, Sensors, Optical filters, Spatial frequencies

SPIE Journal Paper | 1 March 2001

Application of improved phase-measuring profilometry in nonconstant environmental light

Wansong Li, Xianyu Su

OE, Vol. 40, Issue 03, (March 2001) https://doi.org/10.1117/12.10.1117/1.1349212

KEYWORDS: Fringe analysis, Modulation, Phase shift keying, Error analysis, Calibration, Environmental sensing, 3D modeling, Charge-coupled devices, Optical engineering, Computer simulations

Proceedings Article | 6 October 2000 Paper

Improved phase-unwrapping algorithm based on modulation and phase reliability

Wansong Li, Xianyu Su

Proceedings Volume 4231, (2000) https://doi.org/10.1117/12.402838

KEYWORDS: Phase shift keying, Modulation, Reliability, Floods, Error analysis, Reflectivity, Phase measurement, Optics manufacturing, Fringe analysis, Eye models

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Proceedings Article | 19 July 1999 Paper

Phase-shift error calibration in modulation measurement profilometry

Likun Su, Wansong Li, Xianyu Su, Liqun Xiang

Proceedings Volume 3749, (1999) https://doi.org/10.1117/12.354877

KEYWORDS: Modulation, Phase shift keying, Calibration, 3D metrology, Fringe analysis, Lithium, Optoelectronics, CCD cameras, Aluminum, Structured light

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Proceedings Article | 19 July 1999 Paper

Simultaneous calibration algorithm of phase-shifting based on FFT

Wansong Li, Likun Su, Xianyu Su, Liqun Xiang

Proceedings Volume 3749, (1999) https://doi.org/10.1117/12.354876

KEYWORDS: Phase shifts, Calibration, Phase shifting, Phase shift keying, Modulation, Fringe analysis, Control systems, Fourier transforms, Optoelectronics, 3D modeling

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Proceedings Article | 19 July 1999 Paper

New Fourier transform profilometry based on modulation measurement

Xianyu Su, Likun Su, Wansong Li

Proceedings Volume 3749, (1999) https://doi.org/10.1117/12.354824

KEYWORDS: Modulation, Fourier transforms, Fringe analysis, 3D metrology, Phase measurement, Three dimensional sensing, 3D surface sensing, 3D modeling, Phase shift keying, Moire patterns

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Proceedings Article | 10 August 1998 Paper

Practical coordinate mapping method for phase-measuring profilometry

Wansong Li, Xianyu Su, Likun Su, Liqun Xiang

Proceedings Volume 3558, (1998) https://doi.org/10.1117/12.318369

KEYWORDS: Charge-coupled devices, Calibration, Cameras, CCD cameras, Computing systems, Imaging systems, Zoom lenses, Associative arrays, Lithium, Optoelectronics

Proceedings Article | 10 August 1998 Paper

New 3D profilometry based on modulation measurement

Xianyu Su, Likun Su, Wansong Li, Liqun Xiang

Proceedings Volume 3558, (1998) https://doi.org/10.1117/12.318337

KEYWORDS: Modulation, 3D metrology, Phase shift keying, Phase measurement, Three dimensional sensing, 3D surface sensing, Optics manufacturing, Radar, Imaging systems, Structured light

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Showing 5 of 15 publications

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