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Displaying 1-15 out of 15 total
Linear solution for the pose estimation of noncentral catadioptric systems
Found in: Computer Vision, IEEE International Conference on
By Nuno Goncalves, Helder Araujo
Issue Date:October 2007
pp. 1-7
This paper presents a linear method to estimate the pose of a noncentral catadioptric system with a quadric shaped mirror in relation to a world reference frame (or local reference frame without loss of generality). The vision system is assumed to be calib...
 
Point-based calibration using a parametric representation of the general imaging model
Found in: Computer Vision, IEEE International Conference on
By Pedro Miraldo,Helder Araujo,Joao Queiro
Issue Date:November 2011
pp. 2304-2311
Generic imaging models can be used to represent any camera. These models are specially suited for non-central cameras for which closed-form models do not exist. Current models are discrete and define a mapping between each pixel in the image and a straight...
 
Projection Model, 3D Reconstruction and Rigid Motion Estimation from Non-Central Catadioptric Images
Found in: 3D Data Processing Visualization and Transmission, International Symposium on
By Nuno Gonçalves, Helder Araújo
Issue Date:September 2004
pp. 325-332
This paper addresses the problem of rigid motion estimation and 3D reconstruction in vision systems where it is possible to recover the incident light ray direction from the image points. Such systems include pinhole cameras and catadioptric cameras. Given...
 
Rigid Motion Estimation from Non-Central Catadioptric Images
Found in: Pattern Recognition, International Conference on
By Nuno Gonçalves, Helder Araújo
Issue Date:August 2004
pp. 268-271
This paper addresses the problem of rigid motion estimation and 3D reconstruction in vision systems where it is possible to recover the incident direction from image points. Such systems include pinhole cameras and catadioptric cameras. Given two images of...
 
Mirror shape recovery from image curves and intrinsic parameters: Rotationally symmetric and conic mirrors
Found in: Computer Vision and Pattern Recognition Workshop
By Nuno Gonçalves, Helder Araújo
Issue Date:June 2003
pp. 69
This paper analyzes the problem of the estimation of the local mirror shape in a catadioptric imaging system. We propose a method to recover the 3D coordinates of mirror surface points as long as there are images of those points, i.e., as long as there is ...
 
Direct Least Square Fitting of Paracatadioptric Line Images
Found in: Computer Vision and Pattern Recognition Workshop
By Joao P. Barreto, Helder Araujo
Issue Date:June 2003
pp. 78
Paracatadioptric sensors combine a parabolic shaped mirror and a camera inducing an orthographic projection. Such a configuration provides a wide field of view while keeping a single effective viewpoint. In general the paracatadioptric image of a line is a...
 
Differential Epipolar Constraint in Mobile Robot Egomotion Estimation
Found in: Pattern Recognition, International Conference on
By Xavier Armangué, Helder Araújo, Joaquim Salvi
Issue Date:August 2002
pp. 30599
The estimation of camera egomotion is a well established problem in computer vision. Many approaches have been proposed based on both the discrete and the differential epipolar constraint. The discrete case is mainly used in self-calibrated stereoscopic sy...
 
Issues on the Geometry of Central Catadioptric Image Formation
Found in: Computer Vision and Pattern Recognition, IEEE Computer Society Conference on
By Joao P. Barreto, Helder Araujo
Issue Date:December 2001
pp. 422
An imaging system with a single effective viewpoint is called a central projection system. The conventional perspective camera is an example of a central projection system. Systems using mirrors to enhance the field of view while keeping a unique center of...
 
Model Predictive Control to Improve Visual Control of Motion: Applications in Active Tracking of Moving Targets
Found in: Pattern Recognition, International Conference on
By João P. Barreto, Jorge Batista, Helder Araújo
Issue Date:September 2000
pp. 4732
This paper deals with active tracking of 3D moving targets. Visual tracking is presented as a regulation control problem. The performance and robustness in visual control of motion depends on both the vision algorithms and the control structure. Delays and...
 
Binocular Tracking and Accommodation Controlled by Retinal Motion Flow
Found in: Pattern Recognition, International Conference on
By Jorge Batista, Paulo Peixoto, Helder Araújo
Issue Date:September 2000
pp. 1171
In this paper, we described a tracking and accommodation system controlled by retinal motion flow. The tracking system is decomposed in two basic behaviors: smooth-pursuit and vergence. Both behaviors are optical flow based. The eye accommodation (focusing...
 
A Surveillance System Combining Peripheral and Foveated Motion Tracking
Found in: Pattern Recognition, International Conference on
By Paulo Peixoto, Jorge Batista, Helder Araujo
Issue Date:August 1998
pp. 574
No summary available.
 
Geometric Properties of Central Catadioptric Line Images and Their Application in Calibration
Found in: IEEE Transactions on Pattern Analysis and Machine Intelligence
By João P. Barreto, Helder Araujo
Issue Date:August 2005
pp. 1327-1333
In central catadioptric systems, lines in a scene are projected to conic curves in the image. This work studies the geometry of the central catadioptric projection of lines and its use in calibration. It is shown that the conic curves where the lines are m...
 
Paracatadioptric Camera Calibration Using Lines
Found in: Computer Vision, IEEE International Conference on
By Joao P. Barreto, Helder Araujo
Issue Date:October 2003
pp. 1359
Paracatadioptric sensors combine a parabolic shaped mirror and a camera inducing an orthographic projection. Such a configuration provides a wide field of view while keeping a single effective viewpoint. Previous work in central catadioptric sensors proved...
 
Estimation of 3D Motion from Stereo Images — Differential and Discrete Formulations
Found in: Pattern Recognition, International Conference on
By Nuno Gonçalves, Helder Araújo
Issue Date:August 2002
pp. 10335
In this paper we analyze the problem of motion estimation from a sequence of stereo images. We formulate both the differential and discrete approaches of two methods. The differential approach uses differential optical flow whereas the discrete approaches ...
 
Iterative Multi-Step Explicit Camera Calibration
Found in: Computer Vision, IEEE International Conference on
By Jorge Batista, Helder Araújo, A. T. de Almeida
Issue Date:January 1998
pp. 709
Perspective camera calibration has been in the last decades a research subject for a large group of researchers and as a result several camera calibration methodologies can be found in the literature. However only a small number of those methods base their...
 
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