scholarly journals Image Distortion and Rectification Calibration Algorithms and Validation Technique for a Stereo Camera

Electronics ◽  
2021 ◽  
Vol 10 (3) ◽  
pp. 339
Author(s):  
Jonguk Kim ◽  
Hyansu Bae ◽  
Suk Gyu Lee
Keyword(s):  
Stereo Camera ◽  
Calibration Problem ◽  
Calibration Methods ◽  
Stereo Cameras ◽  
Vehicle Systems ◽  
Single Process ◽  
New Methodologies ◽  
Disparity Maps ◽  
Validation Technique ◽  
Smart Cars

This paper focuses on the calibration problem using stereo camera images. Currently, advanced vehicle systems such as smart cars and mobile robots require accurate and reliable vision in order to detect obstacles and special marks around. Such modern vehicles can be equipped with sensors and cameras together or separately. In this study, we propose new methodologies of stereo camera calibration based on the correction of distortion and image rectification. Once the calibration is complete, the validation of the corrections is presented followed by an evaluation of the calibration process. Usually, the validation section is not jointly considered with the calibration in other studies. However, the mass production of cameras widely uses the validation techniques in calibrations owned by manufacturing businesses. Here, we aim to present a single process for the calibration and validation of stereo cameras. The experiment results showed the disparity maps in comparison with another study and proved that the proposed calibration methods can be efficient.

An Experimental Analysis of the Effects of Different Hardware Setups on Stereo Camera Systems

2021 ◽  
Vol 15 (03) ◽  
pp. 337-357
Author(s):  
Alexander Julian Golkowski ◽  
Marcus Handte ◽  
Peter Roch ◽  
Pedro J. Marrón
Keyword(s):  
Experimental Analysis ◽  
Autonomous Navigation ◽  
Indoor Environments ◽  
Camera System ◽  
Stereo Camera ◽  
Camera Systems ◽  
Sensing Technology ◽  
Stereo Cameras ◽  
The Impact ◽  
General Guidance

For many application areas such as autonomous navigation, the ability to accurately perceive the environment is essential. For this purpose, a wide variety of well-researched sensor systems are available that can be used to detect obstacles or navigation targets. Stereo cameras have emerged as a very versatile sensing technology in this regard due to their low hardware cost and high fidelity. Consequently, much work has been done to integrate them into mobile robots. However, the existing literature focuses on presenting the concepts and algorithms used to implement the desired robot functions on top of a given camera setup. As a result, the rationale and impact of choosing this camera setup are usually neither discussed nor described. Thus, when designing the stereo camera system for a mobile robot, there is not much general guidance beyond isolated setups that worked for a specific robot. To close the gap, this paper studies the impact of the physical setup of a stereo camera system in indoor environments. To do this, we present the results of an experimental analysis in which we use a given software setup to estimate the distance to an object while systematically changing the camera setup. Thereby, we vary the three main parameters of the physical camera setup, namely the angle and distance between the cameras as well as the field of view and a rather soft parameter, the resolution. Based on the results, we derive several guidelines on how to choose the parameters for an application.

Compressive Stereo Cameras for Computing Disparity Maps

2013 ◽  
Author(s):  
Vicha Treeaporn ◽  
Amit Ashok ◽  
Mark A. Neifeld
Keyword(s):  
Stereo Cameras ◽  
Disparity Maps

scholarly journals FUZZY FREE PATH DETECTION BASED ON DENSE DISPARITY MAPS OBTAINED FROM STEREO CAMERAS

2012 ◽  
Vol 20 (02) ◽  
pp. 245-259 ◽  
Author(s):  
NURIA ORTIGOSA ◽  
SAMUEL MORILLAS ◽  
GUILLERMO PERIS-FAJARNÉS ◽  
LARISA DUNAI
Keyword(s):  
Least Squares ◽  
Real Time ◽  
Linear Model ◽  
Free Path ◽  
Fuzzy Rule ◽  
Experimental Results ◽  
Model Free ◽  
Stereo Cameras ◽  
Disparity Maps ◽  
Path Detection

In this paper we propose a fuzzy method to detect free paths in real-time using digital stereo images. It is based on looking for linear variations of depth in disparity maps, which are obtained by processing a pair of rectified images from two stereo cameras. By applying least-squares fitting over groups of disparity maps columns to a linear model, free paths are detected by giving a certainty using a fuzzy rule. Experimental results on real outdoor images are also presented.

scholarly journals An Intelligent Auto-Tracking Vehicle

2012 ◽  
Vol 1 (02) ◽  
pp. 08-13
Author(s):  
Ms. Ritika Dhabalia, Ms. Kritika Dhabalia
Keyword(s):  
Traffic Signal Control ◽  
Intelligent Transport System ◽  
Longitudinal Control ◽  
Intelligent Transport ◽  
Vehicle Systems ◽  
Smart Cars ◽  
Short Time ◽  
Free Ranging ◽  
The Given ◽  
Fundamental Requirement

With gas prices at historic highs and fuel-efficient cars in vogue, the time might be perfect to introduce the Smart Car. The chief goal of this paper is designing a smart car with transportation capabilities of a traditional car. The project introduces ways of making car to sense the environment and navigating on its own. The algorithm is implemented using a freescale’s32-bit MPC5604 microcontroller and CODEWARRIOR (IDE) software. It is based on Free Ranging on Grid Technology (FROG) which uses Automated Guided Vehicle Systems (AGV), which are driverless cars. An AGV is a robotic device that follows marks in the floor. The fundamental requirement for this smart car is to sense the given track in a most efficient and in a considerably very short time. The actuators used for lateral and longitudinal control were a servo and a D.C motor respectively. Thus a model car can be designed with electrical, electronic and mechanical systems and can be travelled in smoother and faster way in the track by electromechanical control. In such automated systems, vehicles are programmed to have various features to ensure smooth car navigation, traffic signal control, cameras to monitor and systems to maintain appropriate speed limits etc. Thus in future, this kind of smart cars acts as an intelligent transport system.

scholarly journals Equal Baseline Camera Array—Calibration, Testbed and Applications

2021 ◽  
Vol 11 (18) ◽  
pp. 8464
Author(s):  
Adam L. Kaczmarek ◽  
Bernhard Blaschitz
Keyword(s):  
Stereo Matching ◽  
Outdoor Environment ◽  
Learning Technology ◽  
Disparity Map ◽  
Stereo Camera ◽  
Camera Array ◽  
3D Data ◽  
Novel Approach ◽  
Calibration Methods ◽  
Wide Range

This paper presents research on 3D scanning by taking advantage of a camera array consisting of up to five adjacent cameras. Such an array makes it possible to make a disparity map with a higher precision than a stereo camera, however it preserves the advantages of a stereo camera such as a possibility to operate in wide range of distances and in highly illuminated areas. In an outdoor environment, the array is a competitive alternative to other 3D imaging equipment such as Structured-light 3D scanners or Light Detection and Ranging (LIDAR). The considered kinds of arrays are called Equal Baseline Camera Array (EBCA). This paper presents a novel approach to calibrating the array based on the use of self-calibration methods. This paper also introduces a testbed which makes it possible to develop new algorithms for obtaining 3D data from images taken by the array. The testbed was released under open-source. Moreover, this paper shows new results of using these arrays with different stereo matching algorithms including an algorithm based on a convolutional neural network and deep learning technology.

scholarly journals USING AN LOW-COST STEREO CAMERA FOR AUTONOMOUS NAVIGATION OF MOBILE ROBOT

2020 ◽  
Vol XLIII-B1-2020 ◽  
pp. 423-427
Author(s):  
A. G. Chibunichev ◽  
A. P. Makarov ◽  
E. V. Poliakova
Keyword(s):  
Mobile Robot ◽  
Autonomous Navigation ◽  
Focal Length ◽  
Low Cost ◽  
Experimental Studies ◽  
Stereo Pair ◽  
Stereo Camera ◽  
First Case ◽  
Stereo Cameras ◽  
Autonomous Robot Navigation

Abstract. The paper considers the possibility of using low-cost stereo cameras for autonomous robot navigation. An low-cost stereo camera with a focal length of 5 mm and a photo base of 6 cm was chosen for the research. Experimental studies have shown that the accuracy of determining the coordinates of object points from a pair of images obtained by such a stereo camera is sufficient for organizing autonomous navigation of the robot. In order to improve the reliability and accuracy of determining the trajectory of the robot, this paper proposes to use two stereo cameras. One is directed forward by the robot's movement, and the other is directed at the nadir. Thus, the trajectory is determined twice, independently of each other. Moreover, each case has its own algorithm for finding the homologue points. In the first case, a sparse point cloud is constructed for each stereo pair based on the selection of interesting points and their identification based on the comparison of descriptors. In addition, blunder detection of points identification are realized based on the analysis of the values of the relative orientation equations using the fundamental matrix. In the second case, when the stereo camera is pointed at the nadir, the usual method of correlation is used in the nodes of the grid specified at one image. Experimental studies have shown sufficient efficiency of autonomous navigation of mobile robot based on the use of two stereo cameras.

scholarly journals 3D Vision System for a Robotic Arm Based on Equal Baseline Camera Array

2019 ◽  
Vol 99 (1) ◽  
pp. 13-28
Author(s):  
Adam L. Kaczmarek
Keyword(s):  
Stereo Matching ◽  
Vision System ◽  
Robotic Arm ◽  
Light Conditions ◽  
3D Vision ◽  
Measuring Devices ◽  
Camera Array ◽  
Stereo Cameras ◽  
3D Scanners ◽  
Disparity Maps

AbstractThis paper presents a lightweight 3D vision system called Equal Baseline Camera Array (EBCA). EBCA can work in different light conditions and it can be applied for measuring large range of distances. The system is a useful alternative to other known distance measuring devices such as structured-light 3D scanners, time-of-flight cameras, Light Detection and Ranging (LIDAR) devices and structure from motion techniques. EBCA can be mounted on a robotic arm without putting significant load on its construction. EBCA consists of a central camera and a ring of side cameras. The system uses stereo matching algorithms to acquire disparity maps and depth maps similarly as in case of using stereo cameras. This paper introduces methods of adapting stereo matching algorithms designed for stereo cameras to EBCA. The paper also presents the analysis of local, semi-global and global stereo matching algorithms in the context of the EBCA usage. Experiments show that, on average, results obtained from EBCA contain 37.49% less errors than the results acquired from a single stereo camera used in the same conditions.

scholarly journals A Fast Calibration Method for Phased Arrays by Using the Graph Coloring Theory

Sensors ◽  
2018 ◽  
Vol 18 (12) ◽  
pp. 4315 ◽  
Author(s):  
Lijie Yang ◽  
Ruirui Dang ◽  
Min Li ◽  
Kailong Zhao ◽  
Chunyi Song ◽  
...  
Keyword(s):  
Graph Coloring ◽  
Large Scale ◽  
Phased Array ◽  
Phased Arrays ◽  
Calibration Method ◽  
Omnidirectional Antenna ◽  
Phase Errors ◽  
Calibration Problem ◽  
Calibration Methods ◽  
Calibration Time

Phased array radars are able to provide highly accurate airplane surveillance and tracking performance if they are properly calibrated. However, the ambient temperature variation and device aging could greatly deteriorate their performance. Currently, performing a calibration over a large-scale phased array with thousands of antennas is time-consuming. To facilitate the process, we propose a fast calibration method for phased arrays with omnidirectional radiation patterns based on the graph coloring theory. This method transforms the calibration problem into a coloring problem that aims at minimizing the number of used colors. By reusing the calibration time slots spatially, more than one omnidirectional antenna can perform calibration simultaneously. The simulation proves this method can prominently reduce total calibration time and recover the radiation pattern from amplitude and phase errors and noise. It is worth noting that the total calibration time consumed by the proposed method remains constant and is negligible compared with other calibration methods.

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