Rigoberto Juarez-Salazar

Rigoberto Juarez-Salazar
Instituto Politécnico Nacional | IPN · Centro de Investigación y Desarrollo de Tecnología Digital

PhD

About

62
Publications
9,061
Reads
How we measure 'reads'
A 'read' is counted each time someone views a publication summary (such as the title, abstract, and list of authors), clicks on a figure, or views or downloads the full-text. Learn more
342
Citations
Introduction
Rigoberto Juarez-Salazar currently works at the Instituto Politécnico Nacional, Centro de Investigación y Desarrollo de Tecnología Digital. Rigoberto does research in Opto-digital Image Processing, Three-dimensional Scanning, Optical Metrology, and Visual Navigation, among others. http://rjuarezs.com
Additional affiliations
January 2015 - December 2015
Benemérita Universidad Autónoma de Puebla
Position
  • PostDoc Position
January 2015 - October 2015
Universidad Tecnológica de la Mixteca
Position
  • PostDoc Position

Publications

Publications (62)
Article
Fringe projection profilometry requires calibrating both cameras and projectors for metric measurements. Cameras are relatively simple to calibrate, but projectors require more sophisticated procedures. In this paper, a fringe projection profilometer with two calibrated cameras and one uncalibrated projector is developed for metric measurements. A...
Article
Full-text available
Existing feature-based methods for homography estimation require several pointcorrespondences in two images of a planar scene captured from different perspectives. These methods are sensitive to outliers and their effectiveness depends strongly on the number and accuracy of the specified points. This work presents an iterative method for homography...
Chapter
Accurate homography estimation is a crucial step for many computer vision applications. Nevertheless, nonlinear optical camera imaging effects can introduce radial distortion, making unfeasible the pinhole model for homography estimation. In this paper, an algorithm to rectify radially distorted images using the Maple software is proposed. First, t...
Article
Camera modeling and calibration are essential tasks in modern optics. Conventionally, the pinhole model is adopted with a further extension for lens distortion. However, pinhole and distortion models are mutually dependent; thus, the standard approach induces systematic camera calibration errors. This research presents a unifying distorted pinhole...
Article
Full-text available
Phase-shifting is a powerful phase demodulation method for three-dimensional imaging by fringe projection. However, numerous fringe patterns, which encode a single-phase function, are required. In this paper, the use of intensity patterns, which encode multiple phase functions, is proposed. A multi-demodulation phase-shifting algorithm and the inte...
Article
Full-text available
A reliable method for the detection and tracking of facial landmarks in image sequences is presented. Given a set of prespecified facial landmarks in a reference face image, a bank of composite matched filters is constructed for reliable detection and accurate location of the landmarks in an input image sequence. The filter bank is dynamically adap...
Article
Full-text available
This research presents the design of a real-time system to remove the effects of haze in a sequence of monocular images. The system firstly estimates the medium transmission function from an observed hazy image using locally adaptive neighborhoods and calculation of order statistics. Next, the haze-free image is retrieved using the estimated transm...
Article
Full-text available
The design of matched filters for optical correlators requires explicit knowledge of the shape of the target. This requirement limits its usefulness in applications where the appearance of the target is unspecified or dynamically changing. This research presents the design of an adaptive correlation filter by the optimization of the mean-squared-er...
Conference Paper
Full-text available
A real-time system for restoration of images degraded by haze is presented. First, a transmission function estimator is automatically constructed using genetic programming. Next, the resultant estimator is employed to compute the transmission function of the scene by processing an input hazy image. Finally, the estimated transmission function and t...
Article
Full-text available
Camera-projector calibration is essential in structured-light systems for three-dimensional imaging. A prevalent difficulty for calibration is that two different checkerboards must be captured. First, a physical checkerboard on the reference plane is required to obtain the camera parameters. Second, the physical checkerboard must be removed because...
Article
Fringe projection systems encode the scanned object shape as a phase distribution according to the system parameters. However, to obtain the object shape in physical units of length, the demodulated phase must be converted to the coordinates of the observed points on the object surface. The design of a phase-to-coordinate conversion algorithm is st...
Article
Interference is an important phenomenon that plays a key role in understanding the properties of light. However, novice students have difficulties with optical interference experiments because fringe-pattern processing algorithms are not a topic of optics courses. The difficulty increases taking into account that the phase shift is usually induced...
Conference Paper
Full-text available
Stereo matching is challenging due to the presence of perspective distortions and noise. Commonly, stereo matching algorithms utilize local matching techniques to determine the correspondence of two pixels of the same point in a scene. This work presents a stereo matching algorithm based on locally-adaptive windows and correlation filtering. The pr...
Article
The homography matrix is crucial for many optical metrology applications, such as three-dimensional surface imaging by structured-light projection. In this paper, a straightforward homography estimation method using the image of three particular points on the reference plane is proposed. For this, a new square-radial checkerboard pattern designed t...
Conference Paper
Full-text available
Image restoration consists in retrieving an original image by processing captured images of a scene which are degraded by noise, blurring or optical scattering. Commonly restoration algorithms utilize a single monocular image of the observed scene by assuming a known degradation model. In this approach, valuable information of the three dimensional...
Article
Full-text available
An operator-based approach for the study of homogeneous coordinates and projective geometry is proposed. First, some basic geometrical concepts and properties of the operators are investigated in the one- and two-dimensional cases. Then, the pinhole camera model is derived, and a simple method for homography estimation and camera calibration is exp...
Article
A simple method to estimate the amplitude and standard deviation of sinusoidal signals corrupted with additive Gaussian noise is proposed. For this, a two-parameter model is developed by sorting the samples of the signal. This reduced parametric model allows robust parameter estimation, even if the phase function of the sinusoid is nonlinear, disco...
Article
Abstract A simple method to estimate the position of a camera device with respect to a reference plane is proposed. The method utilizes a crossed grating in the reference plane and exploits the coordinate transformation induced by the perspective projection. If the focal length is available, the position of the camera can be estimated with a single...
Conference Paper
The perspective and lens distortions induced by the imaging system of a camera device are corrected by using an elementary geometrical approach. We propose a simple method based on the use of a crossed grating in the reference plane and a phase demodulation process. Preliminary results showing the performance of the proposed method are discussed.
Conference Paper
A simple method to evaluate the focal length of concave mirrors is proposed. The inverse ray-tracing approach of the Ronchi test is used in the measurement stage. The theoretical principles are given and a numerical method for ronchigram processing is proposed. The results verify the feasibility of the proposal.
Conference Paper
A reliable method for three-dimensional digitization of human faces based on the fringe projection technique is presented. The proposed method employs robust fringe analysis algorithms for robust phase computation. The quality of the resultant 3D face model is characterized in terms of accuracy of surface computation using objective metrics. We pre...
Poster
Full-text available
Recent computer vision applications require the modeling and synthesis of realistic human faces. 3D face digitization is a challenging task due to non-uniform illumination, image distortions, and noise. Fringe-projection is a reliable method for 3D digitization of human faces. This work presents the usefulness of the fringe-projection method in the...
Article
A geometrical model based on an inverse ray-tracing approach to describe the Ronchi test for a concave spherical mirror is presented. In contrast to the conventional ray-tracing method, which refers to information unavailable in ronchigrams, the proposed model provides an explicit relation between the available information in the ronchigram and the...
Conference Paper
Numerical results are presented to show the characterization of an electromechanical actuator capable to achieve equally spaced phase shifts and fraction linear wavelength displacements aided by an interface and a computational system. Measurements were performed by extracting the phase with consecutive interference patterns obtained in a Michelson...
Article
Full-text available
Some advances in fringe analysis technology for phase computing are presented. A full scheme for phase evaluation, applicable to automatic applications, is proposed. The proposal consists of: a fringe-pattern normalization method, Fourier fringe-normalized analysis, generalized phase-shifting processing for inhomogeneous nonlinear phase shifts and...
Article
Full-text available
A simple camera calibration method based on the principle of phase encoding and coordinate transformation is proposed. We use a reference coordinate frame encoded as a phase distribution by multiplexing the x and y directions. From this, we suggest a phase demodulation system. The coordinate transformation induced by the imaging is exploited to est...
Conference Paper
Full-text available
An alternative method for phase-shifting interferometry of two steps by using a speckle interferometer is proposed. It is shown that the introduced phase-step could be unknown because the use of an appropriate fringe-pattern processing. The acquired fringe patterns are processed by well established phase-shifting algorithms in order to compare thes...
Data
Full-text available
A cascade least-squares scheme for wrapped phase extraction using two or more phase-shifted fringe-patterns with unknown and inhomogeneous surface phase shift is proposed. This algorithm is based on the parameter estimation approach to process fringe-patterns where, except for the interest phase distribution that is a function of the space only, al...
Article
Full-text available
A cascade least-squares scheme for wrapped phase extraction using two or more phase-shifted fringe-patterns with unknown and inhomogeneous surface phase shift is proposed. This algorithm is based on the parameter estimation approach to process fringe-patterns where, except for the interest phase distribution that is a function of the space only, al...
Article
Full-text available
A simple and efficient phase-unwrapping algorithm based on a rounding procedure and a global least-squares minimization is proposed. Instead of processing the gradient of the wrapped phase, this algorithm operates over the gradient of the phase jumps by a robust and noniterative scheme. Thus, the residue-spreading and over-smoothing effects are red...
Conference Paper
Full-text available
A faster and robust generalized phase-shifting interferometry suitable to automatic real-time applications is presented. The proposal is based on the parameter estimation by the least squares method. The algorithm can retrieve the wrapped phase from two or more phase shifted interferograms with unknown phase steps between 0 and Pi rad. Moreover, by...
Conference Paper
Full-text available
The fringe-pattern normalization method by parameter estimation is used to relieve the critical filter's requirements in the Fourier transform method for phase demodulation. By the normalization procedure, the zero order spectrum is suppressed allowing a straightforward filtering in the Fourier transform method. Thus, the filtering procedure is car...
Article
Full-text available
A simple and inexpensive optical setup to phase-shifting interferometry is proposed. This optical setup is based on the Twyman-Green Interferometer where the phase shift is induced by the lateral displacement of the point laser source. A theoretical explanation of the induced phase by this alternative method is given. The experimental results are c...
Article
Full-text available
The simple filtering procedure, high spatial resolution, and low computation time benefits of Fourier normalized-fringe analysis are verified. For this, both the fringe-pattern normalization method by parameter estimation using the least squares method and the standard Fourier transform method are implemented. This proposal, or any Fourier normaliz...
Article
A simple non-iterative algorithm for generalized phase-shifting interferometry is proposed. This algorithm recovers the wrapped phase from two or more interferograms with unknown phase steps between 0 and p rad. The proposal is based on the least squares method to calculate four parameters: background and modulation light, phase steps and wrapped p...
Data
A simple non-iterative algorithm for generalized phase-shifting interferometry is proposed. This algorithm recovers the wrapped phase from two or more interferograms with unknown phase steps between 0 and p rad. The proposal is based on the least squares method to calculate four parameters: background and modulation light, phase steps and wrapped p...
Conference Paper
Full-text available
In this work we propose the simulation of a fringe pattern in analogy with a oscilating pendulum with adaptive parameters. This technique will be used in future to recovery the phase of interferograms by mean a dynamical model. We reproduce a reference fringe pattern solving the dynamical model of a pen-dulum with adaptive length parameter, by comp...

Network

Cited By

Projects

Projects (2)
Project
Restoration of images degraded by haze is challenging because several physical factors are involved in the image formation process. Over the years, several existing methods have been proposed to solve this problem. However, despite important advances there still remain several issues to be solved. For instance, suppressing of the effects of haze in captured images by preserving original image colors and avoiding overprocessing effects and introduction of artificial artifacts to restored images. This research project has the aim to design advanced opto-digital methods to solve effectively the problem of image dehazing by the optimization of objective performance metrics. Additionally, efficient opto-digital implementations of the designed methods for real-time applications are considered.
Project
Template matching is a classic technique for object recognition in images. This technique, can produce high detection rate and accuracy of location estimation of detected objects in the presence of additive and disjoint noise in the scene. However, its performance can be diminished if the objects suffer from visual modifications due to nonuniform illumination, rotations, scaling, deformations, among others. In robot vision it is required robust and accurate algorithms for object recognition in the presence of real-life scene perturbations. The goal of this project is to design new algorithms based on template matching to increase the accuracy and robustness of object recognition for robot vision applications.