Dr. Ricardo Legarda-Sáenz Profile

Dr. Ricardo Legarda-Sáenz

Researcher at Univ Autonoma de Yucatan

Area of Expertise:

Scientific computing , Camera calibration , Fringe processing , Parallel computing

Websites:

Personal Website

My principal research interest is the applications of optical shape measurement for the evaluation of complex objects. At present, I am working in the calibration and measurement of a fringe projection system, and the measured data matching from different views and/or different devices. Secondary interests are the processing of fringe patterns using inverse-problems approach, and applications with moire deflectometry. In these topics, papers were published in peer-review journals.

SPIE Journal Paper | 28 April 2018

Comparison of multihardware parallel implementations for a phase unwrapping algorithm

Francisco Javier Hernandez-Lopez, Mariano Rivera, Adan Salazar-Garibay, Ricardo Legarda-Sáenz

OE, Vol. 57, Issue 04, 043113, (April 2018) https://doi.org/10.1117/12.10.1117/1.OE.57.4.043113

KEYWORDS: Synthetic aperture radar, Image processing, MATLAB, Optical engineering, Image analysis, Magnetic resonance imaging, Interferometric synthetic aperture radar, Algorithm development, Field programmable gate arrays, Computer programming

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Proceedings Article | 6 September 2017 Paper

A Wiener filter approach to shape from shading

Oscar Castillo, Jorge Flores, Antonio Muñoz, Ricardo Legarda-Saenz

Proceedings Volume 10410, 104101D (2017) https://doi.org/10.1117/12.2274133

KEYWORDS: Linear filtering, Reconstruction algorithms, Reflectivity, 3D image reconstruction, Cameras, Light sources, 3D image processing, 3D modeling, Machine vision, 3D vision

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Proceedings Article | 12 September 2014 Paper

3D shape measurement with binary phase-shifted technique and digital filters

Adriana Silva, Ricardo Legarda-Saenz, G. García-Torales, Sandra Balderas-Mata, Jorge Flores

Proceedings Volume 9219, 92190L (2014) https://doi.org/10.1117/12.2062479

KEYWORDS: Binary data, 3D metrology, Projection systems, Modulation, Gaussian filters, Digital filtering, Picosecond phenomena, Phase shifts, Phase shift keying, Linear filtering

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Proceedings Article | 19 September 2013 Paper

Wavefront recovery Fourier-based algorithm used in a vectorial shearing interferometer

Beethoven Bravo-Medina, G. Garcia-Torales, Ricardo Legarda-Sáenz, Jorge Flores

Proceedings Volume 8867, 88670Z (2013) https://doi.org/10.1117/12.2025316

KEYWORDS: Wavefronts, Prisms, Shearing interferometers, Modulation, Phase measurement, Electroluminescent displays, Optical components, Interferometers, Wavefront reconstruction, Control systems

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Proceedings Article | 19 September 2013 Paper

Measurement of phase objects by the use of color phase-shifting technique

Oscar Castillo, Ricardo Legarda-Sáenz, Jorge Flores, G. Garcia-Torales

Proceedings Volume 8867, 886710 (2013) https://doi.org/10.1117/12.2025202

KEYWORDS: Fringe analysis, Phase measurement, Wavefronts, LCDs, Phase shifts, Cameras, CCD cameras, Image processing, Distortion, Refractive index

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Proceedings Article | 3 November 2011 Paper

Real-time parallel method for quadrature transform estimation and 3D surface measurement

Arturo Espinosa-Romero, Ricardo Legarda-Saenz

Proceedings Volume 8011, 80117A (2011) https://doi.org/10.1117/12.902175

KEYWORDS: Fringe analysis, 3D metrology, Algorithm development, Software, Graphics processing units, Visualization, Data processing, Phase shift keying, Fourier transforms, Computer programming

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SPIE Journal Paper | 1 April 2011 Open Access

Wavefront reconstruction using multiple directional derivatives and Fourier transform

Ricardo Legarda-Sáenz, Arturo Espinosa-Romero

OE, Vol. 50, Issue 04, 040501, (April 2011) https://doi.org/10.1117/12.10.1117/1.3560540

KEYWORDS: Wavefronts, Fourier transforms, Wavefront reconstruction, Signal to noise ratio, Deflectometry, Optical engineering, Fringe analysis, Data modeling, Interference (communication), Optical instrument design

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Proceedings Article | 3 October 2008 Paper

Fast wavefront estimation using multiple directional derivatives and quadrature transform

Ricardo Legarda-Saenz

Proceedings Volume 7155, 715531 (2008) https://doi.org/10.1117/12.814611

KEYWORDS: Fringe analysis, Wavefronts, Wavefront reconstruction, Demodulation, Cameras, Deflectometry, Inspection, Data acquisition, CCD cameras, Wave propagation

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Proceedings Article | 15 May 2007 Paper

Robust wavefront reconstruction using multiple directional derivatives and computer monitor

Ricardo Legarda-Saenz

Proceedings Volume 6422, 64220W (2007) https://doi.org/10.1117/12.742643

KEYWORDS: Fringe analysis, Wavefront reconstruction, Wavefronts, Demodulation, Cameras, Fourier transforms, Thin films, Transistors, Inspection, CCD cameras

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Proceedings Article | 10 February 2006 Paper

Tridimensional reconstruction using structured light systems

Ricardo Legarda-Saenz

Proceedings Volume 6046, 60461M (2006) https://doi.org/10.1117/12.674561

KEYWORDS: Calibration, 3D metrology, Cameras, Imaging systems, Phase measurement, Projection systems, Sensors, Optical testing, Fringe analysis, Structured light

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Proceedings Article | 14 February 2005 Paper

New improvements of the regularized phase tracking technique for the processing of non-normalized fringe patterns

Ricardo Legarda-Saenz, Mariano Rivera

Proceedings Volume 5776, (2005) https://doi.org/10.1117/12.611710

KEYWORDS: Fringe analysis, Phase shift keying, Modulation, Demodulation, Detection and tracking algorithms, Amplitude modulation, Control systems, Error analysis, Shape analysis, Refractive index

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SPIE Journal Paper | 1 February 2004

Accurate procedure for the calibration of a structured light system

Ricardo Legarda-Sáenz, Thorsten Bothe, Werner Jüptner

OE, Vol. 43, Issue 02, (February 2004) https://doi.org/10.1117/12.10.1117/1.1635373

KEYWORDS: Calibration, Laser sintering, Projection systems, Cameras, 3D modeling, Error analysis, Mathematical modeling, Instrument modeling, 3D acquisition, Structured light

Proceedings Article | 30 May 2003 Paper

Three-dimensional camera

Thorsten Bothe, Achim Gesierich, Ricardo Legarda-Saenz, Werner Jueptner

Proceedings Volume 5144, (2003) https://doi.org/10.1117/12.501959

KEYWORDS: Calibration, Stereoscopic cameras, Cameras, 3D metrology, Projection systems, Imaging systems, 3D modeling, Phase measurement, LCDs, Distance measurement

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Industrial- and multimedia applications need cost effective, compact and flexible 3D profiling instruments. In the talk we will show the principle of, applications for and results from a new miniaturized 3-D profiling system for macroscopic scenes. The system uses a compact housing and is usable like a camera with minimum stabilization like a tripod. The system is based on common fringe projection technique. Camera and projector are assembled with parallel optical axes having coplanar projection and imaging plane. Their axes distance is comparable to the human eyes distance altogether giving a complete system of 21x20x11 cm size and allowing to measure high gradient objects like the interior of tubes. The fringe projector uses a LCD which enables fast and flexible pattern projection. Camera and projector have a short focal length and a high system aperture as well as a large depth of focus. Thus, objects can be measured from a shorter distance compared to common systems (e.g. 1 m sized objects in 80 cm distance). Actually, objects with diameters up to 4 m can be profiled because the set-up allows working with completely opened aperture combined with bright lamps giving a big amount of available light and a high Signal to Noise Ratio. Normally a small basis has the disadvantage of reduced sensitivity. We investigated in methods to compensate the reduced sensitivity via setup and enhanced evaluation methods. For measurement we use synthetic wavelengths. The developed algorithms are completely adaptable concerning the users needs of speed and accuracy. The 3D camera is built from low cost components, robust, nearly handheld and delivers insights also into difficult technical objects like tubes and inside volumes. Besides the realized high resolution phase measurement the system calibration is an important task for usability. While calibrating with common photogrammetric models (which are typically used for actual fringe projection systems) problems were found that originate from the short focal length and the extreme opening angle of the system as well as the large depth of focus. The actual calibration method is outlined and current problems are shown. An improved calibration of the system is discussed for improved results in future.

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