Current Search:  Cameras--Calibration (x)

View All Items

  • CSV Spreadsheet
(1 - 3 of 3)
Camera calibration techniques
Title
Camera calibration techniques.
Creator
Xu, Xuan., Florida Atlantic University, Roth, Zvi S., Zhuang, Hanqi, College of Engineering and Computer Science, Department of Computer and Electrical Engineering and Computer Science
Abstract/Description
In order to facilitate the implementation of RAC-based camera calibration technique, several issues are addressed in this thesis. First, a straightforward extension of the RAC-based camera calibration technique to the case of unknown camera specifications is given. Second, to speed up the calibration process and reduce numerical difficulties, a simplified RAC-based method is presented. The simplified RAC-based method provides a closed-form solution to the camera calibration problem. Third,...
Show moreIn order to facilitate the implementation of RAC-based camera calibration technique, several issues are addressed in this thesis. First, a straightforward extension of the RAC-based camera calibration technique to the case of unknown camera specifications is given. Second, to speed up the calibration process and reduce numerical difficulties, a simplified RAC-based method is presented. The simplified RAC-based method provides a closed-form solution to the camera calibration problem. Third, the PTM-based camera calibration technique is presented to give an example of pre-1985 camera calibration technique. Fourth, a method is devised to compute the ratio of scale factors. Finally, an optimization scheme is suggested to estimate image center. These modifications preserve all the advantages possessed by the original RAC-based calibration technique. The experiment results are provided to illustrate the effectiveness of the present methods.
Show less
Date Issued
1991
PURL
http://purl.flvc.org/fcla/dt/14771
Subject Headings
Cameras--Calibration
Format
Document (PDF)
Synthesis of vision-based robot calibration using moving cameras
Title
Synthesis of vision-based robot calibration using moving cameras.
Creator
Wang, Kuanchih., Florida Atlantic University, Roth, Zvi S., Zhuang, Hanqi, College of Engineering and Computer Science, Department of Computer and Electrical Engineering and Computer Science
Abstract/Description
Robot calibration using a vision system and moving cameras is the focus of this dissertation. The dissertation contributes in the areas of robot modeling, kinematic identification and calibration measurement. The effects of perspective distortion of circular camera calibration points is analyzed. A new modified complete and parametrically continuous robot kinematic model, an evolution of the complete and parametrically continuous (CPC) model, is proposed. It is shown that the model's error...
Show moreRobot calibration using a vision system and moving cameras is the focus of this dissertation. The dissertation contributes in the areas of robot modeling, kinematic identification and calibration measurement. The effects of perspective distortion of circular camera calibration points is analyzed. A new modified complete and parametrically continuous robot kinematic model, an evolution of the complete and parametrically continuous (CPC) model, is proposed. It is shown that the model's error-model can be developed easily as the structure of this new model is very simple and similar to the Denavit-Hartenbert model. The derivation procedure of the error-model follows a systematic method that can be applied to any kind of robot arms. Pose measurement is the most crucial step in robot calibration. The use of stereo as well as mono mobile camera measurement system for collection of pose data of the robot end-effector is investigated. The Simulated Annealing technique is applied to the problem of optimal measurement configuration selection. Joint travel limits can be included in the cost function. It is shown that trapping into local minimum points can be effectively avoided by properly choosing an initial point and a temperature schedule. The concept of simultaneous calibration of camera and robot is developed and implemented as an automated process that determines the system model parameters using only the system's internal sensors. This process uses a unified mathematical model for the entire robot/camera system. The results of the kinematic identification, optimal configuration selection, and simultaneous calibration of robot and camera using the PUMA 560 robot arm have demonstrated that the modified complete and parametrically continuous model is a viable and simple modeling tool, which can achieve desired accuracy. The systematic way of modeling and performing of different kinds of vision-based robot applications demonstrated in this dissertation will pave the way for industrial standardizing of robot calibration done by the robot user on the manufacturing floor.
Show less
Date Issued
1993
PURL
http://purl.flvc.org/fcla/dt/12339
Subject Headings
Robot vision, Robot cameras--Calibration
Format
Document (PDF)
visual looming navigation cue: A unified approach
Title
The visual looming navigation cue: A unified approach.
Creator
Joarder, Kunal., Florida Atlantic University, Raviv, Daniel, College of Engineering and Computer Science, Department of Computer and Electrical Engineering and Computer Science
Abstract/Description
This research introduces a unified approach to visual looming. Visual looming is related to an increasing projected size of an object on a viewer's retina while the relative distance between the viewer and the object decreases. Psychophysicists and neurobiologists have studied this phenomenon by observing vision and action in unison and have reported subject's tendency to react defensively or using this information in an anticipatory control of the body. Since visual looming induces senses of...
Show moreThis research introduces a unified approach to visual looming. Visual looming is related to an increasing projected size of an object on a viewer's retina while the relative distance between the viewer and the object decreases. Psychophysicists and neurobiologists have studied this phenomenon by observing vision and action in unison and have reported subject's tendency to react defensively or using this information in an anticipatory control of the body. Since visual looming induces senses of threat of collision, the same cue, if quantified, can be used along with visual fixation in obstacle avoidance in mobile robots. In quantitative form visual looming is defined as the time derivative of the relative distance (range) between the observer and the object divided by the relative distance itself. The visual looming is a measurable variable. Following the paradigm of Active Vision the approach in this research uses visual fixation to selectively attend a small part of the image, that is relevant to the task. Visual looming provides a time-based mapping from a "set of 2-D image cues" to "time-based 3-D space". This research describes how visual looming, which is a concept related to an object in the 3-D world, can be calculated studying the relative temporal change in the following four different attributes of a sequence of 2-D images: (i) image area; (ii) image brightness; (iii) texture density in the image; (iv) image blur. From a simple closed form expression it shows that a powerful unified approach can be adopted in these methods. An extension of this unified approach establishes a strong relationship with the Weber-Fechner law in Psychophysics. The four different methods explored for the calculation of looming are simple. The experimental results illustrate how the measured values of looming stay close to the actual values. This research also introduces one important visual invariant $\Re$ that exists in relative movements between a camera light-source pair and a visible object. Finally, looming is used in the sense of a threat of collision, to navigate in an unknown environment. The results show that the approach can be used in real-time obstacle avoidance with very little a-priori knowledge.
Show less
Date Issued
1995
PURL
http://purl.flvc.org/fcla/dt/12416
Subject Headings
Robots--Control systems, Robot vision, Robot camera--Calibration
Format
Document (PDF)