Grup de Visió per Computador i Robòtica
Departament d'Electrònica, Informàtica i Automàtica
Institut d'Informàtica i Aplicacions
Escola Politècnica Superior - Universitat de Girona

dir  telèfon:  972 41 9812
   fax:  972 41 8098
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Edifici P-IV, Av. Lluís Santaló, s/n,17071-Girona
  correu electrònic:  radu@eia.udg.es   (spam free email)
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Research Associate
.:: Educational background
2006-present Research Associate
Department of Intelligent Media, Yagi Laboratory, University of Osaka, Japan.
2003-2005 PhD. student
University of Girona, Catalonia, Spain. [more...]
:: Ph.D. in Information Technologies program at the Electronics, Informatics and Automation Department of UdG.
:: Thesis: Catadioptric Stereo based on Structured Light Projection.
:: Achieved skills: project team work, self management, process coordination.
2001-2003 M.S. degree in Computer Science [more...]
University of Girona, Catalonia, Spain.
:: M.S. degree in Computer Science approved with excellent mention from the University of Girona.
:: Relevant coursework: Mobile robotics; 3D perception; Scene interpretation and segmentation; Systems integration: from architectures to communications.
1995-2000 Automatics and Computer Science Engineer
Technical University of Cluj-Napoca, România [more...]
:: Final Thesis: Digital Simulation of Multiquadrant Choppers in Neapolis 4.0. (Frequency modulated power control simulation program). The thesis was elaborated while enrolled at the Technical University of Kavala, Greece and it was granted the top grade by both universities.
:: Automatics and Computer Science Engineering, 5-year, fully taught in English.
   Graduated with 84,2% average.

.:: Research
Currently working on my PhD thesis - co directed by Joaquim Salvi and El Mustapha Mouaddib.

Omnidirectional Vision

Survey on Omnidirectional Vision (PDF file, 1 MB)
Omnidirectional View » Catadioptric cameras » Single View Point cameras
The catadioptric sensors use reflecting surfaces (convex or planar mirrors) coupled to a conventional camera and are usually classified depending on the way they gather the light rays. When all the observed light rays converge into a point, called focus, the sensors are known as Single View Point Catadioptric Cameras (SVP).

The SVP enables distortion-free reconstruction of panoramic images in a familiar form for the human users.
Take a look at a panoramic image and its perspective-like reconstruction.


I am using the two products from Remote Reality : D40 and S80.
                                                                           Parabolic mirror based SVP cameras
Parabolic mirrors form SVP catadioptric devices when used with telecentric optics.
See how a parabolic mirror behaves when placed in front of an orthographic and perspective camera. Note that the perspective camera case doesn't produce a SVP.

  
Parabolic mirror with orthographic camera.    Parabolic mirror with perspective camera.
                                                                           Hyperbolic mirror based SVP cameras
Hyperbolic mirrors form SVP catadioptric devices when used with perspective cameras.
Hyperbolic mirror with perspective camera.

Omnidirectional depth perception
Omnidirectional depth perception is obtained by combining omnidirectional vision and structured light.
The resulting sensor is formed by a single catadioptric camera and an omnidirectional light projector.
Above are shown the diagram of our sensor and two laboratory prototypes.


Sensor calibration
Calibration is the process of estimating the parameters of the model. The camera is calibrated at first and the light projector is subsequently calibrated based on information provided by the camera.

Omnidirectional surveillance
With the model of the omnidirectional camera we can obtain perspective images by unwarping the panoramic ones. This feature is used in a surveillance aplication that allows the operator to automatically track persons entering the surveyed area. The conventional image of an interesting "slice" of the and omnidirectional view is presented to the user.
Three screen-shots of the operator view are presented here.


.:: Publications

CONFERENCES

2005 : R. Orghidan, J. Salvi, E. Mouaddib. Accuracy Estimation of a New Omnidirectional 3D Vision Sensor, IEEE International Conference on Image Processing (ICIP), Genoa, Italy, September 11-14, 2005
2005 : R. Orghidan, E. Mouaddib, J. Salvi. A Computer Vision Sensor for Panoramic Depth Perception, 2nd Iberian Conference on Pattern Recognition and Image Analysis, IbPRIA 2005, Estoril , Portugal, June 7-9, 2005
2005 : R. Orghidan, E. Mouaddib, J. Salvi. Omnidirectional Depth Computation from a Single Image, IEEE International Conference on Robotics and Automation, ICRA 2005, Barcelona, Spain, April 18-22, 2005 [Abstract ...]
Omnidirectional cameras offer a much wider field of view than the perspective ones and alleviate the problems due to occlusions. However, both types of cameras suffer from the lack of depth perception.
A practical method for obtaining depth in computer vision is to project a known structured light pattern on the scene avoiding the problems and costs involved by stereo vision. This paper is focused on the idea of combining omnidirectional vision and structured light with the aim to provide 3D information about the scene.
The resulting sensor is formed by a single catadioptric camera and an omnidirectional light projector. It is also discussed how this sensor can be used in robot navigation applications.
2003 : R. Orghidan, J. Salvi, E. Mouaddib. Calibration Of A Structured Light-Based Stereo Catadioptric Sensor, Computer Vision and Pattern Recognition, Madison, Wisconsin, U.S.A., 2003
2003 : R. Orghidan, E. Mouaddib, J. Salvi. An Omnidirectional Sensor with Embedded Structured Light Projector, SANKEN International Workshop on Intelligent Systems, Osaka, Japan, 2003
2002 : X. Armangué, J. Salvi, R. Orghidan. Mobile Robot Egomotion Estimation using Differential Epipolar Constraint, Cinquè Congrés Català d'Intel·ligència Artificial, Castelló de la Plana, Spain, October 24-25, 2002
2001 : L. Miclea, S. Enyedi, R. Orghidan. Online BIST Experiments for Distributes Systems, Europen Test Workshop, Stockholm, Sweden , 2002

JOURNALS

2005 : R. Orghidan, E. Mouaddib, J. Salvi.
A Computer Vision Sensor for Panoramic Depth Perception,
Lecture Notes in Computer Science, Volume 3522 / 2005, p. 153, Springer-Verlag GmbH, ISBN: 3-540-26153-2
2005 : R. Orghidan, J. Salvi, E. Mouaddib.
Modelling and Accuracy Estimation of a New Omnidirectional Depth Computation Sensor ,
Pattern Recognition Letters,
Accepted for publication on the 16th of December 2005.

.:: Useful links

.:: Personal stuff
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Last update: 21st of September 2005
Darrera actualització: 21 de Setembre del 2005