Comparison of the Performance of the Calibration Algorithm of Wide-Angle Lens

2013 ◽  
Vol 467 ◽  
pp. 323-326
Author(s):  
Jong Eun Ha
Keyword(s):  
Visual Surveillance ◽  
Field Of View ◽  
Experimental Result ◽  
Eye Lens ◽  
Comparison Results ◽  
Calibration Algorithm ◽  
Wide Angle Lens ◽  
Present Experimental Result ◽  
Fish Eye ◽  
Small Field Of View

Fish-eye lens is used in various applications due to wide coverage of scene. In particular, it can be effectively used in visual surveillance and surround monitoring in automotive. It has large radial distortion compared to the conventional lens with small field of view. In this paper, we present comparison results for the calibration of fish-eye lens. We compare two algorithms where one is available in OpenCV [ and the other is Devernay and Faugeras [. Also, we present experimental result according to the number of calibration points, initialization value. We evaluate the accuracy of calibration thorough 3D reconstruction by stereo system. It can give more reliable evaluation than using reprojection eror by single camera.

scholarly journals BIFOCAL STEREO FOR MULTIPATH PERSON RE-IDENTIFICATION

2017 ◽  
Vol XLII-2/W8 ◽  
pp. 37-44 ◽  
Author(s):  
G. Blott ◽  
C. Heipke
Keyword(s):  
Focal Length ◽  
Image Resolution ◽  
Field Of View ◽  
Eye Lens ◽  
Single Camera ◽  
Identification Performance ◽  
Stereo Cameras ◽  
Working Distance ◽  
3D Information ◽  
Fish Eye

This work presents an approach for the task of person re-identification by exploiting bifocal stereo cameras. Present monocular person re-identification approaches show a decreasing working distance, when increasing the image resolution to obtain a higher reidentification performance. We propose a novel 3D multipath bifocal approach, containing a rectilinear lens with larger focal length for long range distances and a fish eye lens of a smaller focal length for the near range. The person re-identification performance is at least on par with 2D re-identification approaches but the working distance of the approach is increased and on average 10% more re-identification performance can be achieved in the overlapping field of view compared to a single camera. In addition, the 3D information is exploited from the overlapping field of view to solve potential 2D ambiguities.

scholarly journals EVALUATION OF THE QUALITY OF ACTION CAMERAS WITH WIDE-ANGLE LENSES IN UAV PHOTOGRAMMETRY

2016 ◽  
Vol XLI-B1 ◽  
pp. 851-859 ◽  
Author(s):  
H. Hastedt ◽  
T. Ekkel ◽  
T. Luhmann
Keyword(s):  
Eye Lens ◽  
Experimental Setup ◽  
Light Weight ◽  
Wide Angle ◽  
Control Points ◽  
Wide Angle Lens ◽  
Standard Calibration ◽  
Normal Lens ◽  
Fish Eye

The application of light-weight cameras in UAV photogrammetry is required due to restrictions in payload. In general, consumer cameras with normal lens type are applied to a UAV system. The availability of action cameras, like the GoPro Hero4 Black, including a wide-angle lens (fish-eye lens) offers new perspectives in UAV projects. With these investigations, different calibration procedures for fish-eye lenses are evaluated in order to quantify their accuracy potential in UAV photogrammetry. Herewith the GoPro Hero4 is evaluated using different acquisition modes. It is investigated to which extent the standard calibration approaches in OpenCV or Agisoft PhotoScan/Lens can be applied to the evaluation processes in UAV photogrammetry. Therefore different calibration setups and processing procedures are assessed and discussed. Additionally a pre-correction of the initial distortion by GoPro Studio and its application to the photogrammetric purposes will be evaluated. An experimental setup with a set of control points and a prospective flight scenario is chosen to evaluate the processing results using Agisoft PhotoScan. Herewith it is analysed to which extent a pre-calibration and pre-correction of a GoPro Hero4 will reinforce the reliability and accuracy of a flight scenario.

scholarly journals EVALUATION OF THE QUALITY OF ACTION CAMERAS WITH WIDE-ANGLE LENSES IN UAV PHOTOGRAMMETRY

2016 ◽  
Vol XLI-B1 ◽  
pp. 851-859 ◽  
Author(s):  
H. Hastedt ◽  
T. Ekkel ◽  
T. Luhmann
Keyword(s):  
Eye Lens ◽  
Experimental Setup ◽  
Light Weight ◽  
Wide Angle ◽  
Control Points ◽  
Wide Angle Lens ◽  
Standard Calibration ◽  
Normal Lens ◽  
Fish Eye

The application of light-weight cameras in UAV photogrammetry is required due to restrictions in payload. In general, consumer cameras with normal lens type are applied to a UAV system. The availability of action cameras, like the GoPro Hero4 Black, including a wide-angle lens (fish-eye lens) offers new perspectives in UAV projects. With these investigations, different calibration procedures for fish-eye lenses are evaluated in order to quantify their accuracy potential in UAV photogrammetry. Herewith the GoPro Hero4 is evaluated using different acquisition modes. It is investigated to which extent the standard calibration approaches in OpenCV or Agisoft PhotoScan/Lens can be applied to the evaluation processes in UAV photogrammetry. Therefore different calibration setups and processing procedures are assessed and discussed. Additionally a pre-correction of the initial distortion by GoPro Studio and its application to the photogrammetric purposes will be evaluated. An experimental setup with a set of control points and a prospective flight scenario is chosen to evaluate the processing results using Agisoft PhotoScan. Herewith it is analysed to which extent a pre-calibration and pre-correction of a GoPro Hero4 will reinforce the reliability and accuracy of a flight scenario.

A Correction Method of Fish-Eye Lens Based on Projective Reconstruction

2014 ◽  
Vol 577 ◽  
pp. 741-744
Author(s):  
Jun Chao Zhu ◽  
Li Wan ◽  
Na Liu ◽  
Bao Feng Zhang
Keyword(s):  
Correction Method ◽  
Eye Lens ◽  
Wide Angle ◽  
Projective Reconstruction ◽  
Wide Angle Lens ◽  
Fish Eye

Fish-eye lens is a special wide angle lens shooting all of the information within 185 degrees at the same time, but the image taken by it cause distortion. In order to fit for people's visual habits, the images need a correction. This article proposes a correction method of fish-eye lens based on projective reconstruction and verified the effectiveness of the method by the experiment.

scholarly journals Multi-functional star tracker — future perspectives

10.14311/1486 ◽  
2011 ◽  
Vol 51 (6) ◽  
Author(s):  
J. Roháč ◽  
M. Řeřábek ◽  
R. Hudec
Keyword(s):  
State Of The Art ◽  
Field Of View ◽  
Star Tracker ◽  
Wide Field ◽  
Small Field ◽  
Future Perspectives ◽  
Precise Information ◽  
Current State ◽  
Fish Eye ◽  
Small Field Of View

This paper focuses on the idea of a multi-functional wide-field star tracker (WFST) and provides a description of the current state-of-the-art in this field. The idea comes from a proposal handed in to ESA at the beginning of 2011. Star trackers (STs) usually have more than one object-lens with a small Field-of-View. They provide very precise information about the attitude in space according to consecutive evaluation of star positions. Our idea of WFST will combine the functions of several instruments, e.g. ST, a horizon sensor, and an all-sky photometry camera. WFST will use a fish-eye lens. There is no comparable product on the present-day market. Nowadays, spacecraft have to carry several instruments for these applications. This increases the weight of the instrumentation and reduces the weight available for the payload.

Very High Resolution Analysis of the Dynamics of a Coronal Plasmoid

1994 ◽  
Vol 144 ◽  
pp. 593-596
Author(s):  
O. Bouchard ◽  
S. Koutchmy ◽  
L. November ◽  
J.-C. Vial ◽  
J. B. Zirker
Keyword(s):  
High Resolution ◽  
Solar Eclipse ◽  
Total Solar Eclipse ◽  
Field Of View ◽  
Small Field ◽  
High Resolution Analysis ◽  
Ccd Observations ◽  
Resolution Analysis ◽  
Very High ◽  
Small Field Of View

AbstractWe present the results of the analysis of a movie taken over a small field of view in the intermediate corona at a spatial resolution of 0.5“, a temporal resolution of 1 s and a spectral passband of 7 nm. These CCD observations were made at the prime focus of the 3.6 m aperture CFHT telescope during the 1991 total solar eclipse.

scholarly journals Day and Night Clouds Detection Using a Thermal-Infrared All-Sky-View Camera

2021 ◽  
Vol 13 (9) ◽  
pp. 1852
Author(s):  
Yiren Wang ◽  
Dong Liu ◽  
Wanyi Xie ◽  
Ming Yang ◽  
Zhenyu Gao ◽  
...  
Keyword(s):  
Infrared Image ◽  
Thermal Infrared ◽  
Field Of View ◽  
Detection Scheme ◽  
Detection Approach ◽  
Cloud Characteristics ◽  
Formation And Evolution ◽  
Fish Eye ◽  
Infrared Channel

The formation and evolution of clouds are associated with their thermodynamical and microphysical progress. Previous studies have been conducted to collect images using ground-based cloud observation equipment to provide important cloud characteristics information. However, most of this equipment cannot perform continuous observations during the day and night, and their field of view (FOV) is also limited. To address these issues, this work proposes a day and night clouds detection approach integrated into a self-made thermal-infrared (TIR) all-sky-view camera. The TIR camera consists of a high-resolution thermal microbolometer array and a fish-eye lens with a FOV larger than 160°. In addition, a detection scheme was designed to directly subtract the contamination of the atmospheric TIR emission from the entire infrared image of such a large FOV, which was used for cloud recognition. The performance of this scheme was validated by comparing the cloud fractions retrieved from the infrared channel with those from the visible channel and manual observation. The results indicated that the current instrument could obtain accurate cloud fraction from the observed infrared image, and the TIR all-sky-view camera developed in this work exhibits good feasibility for long-term and continuous cloud observation.

scholarly journals Proposed New AV-Type Test-Bed for Accurate and Reliable Fish-Eye Lens Camera Self-Calibration

Sensors ◽  
2021 ◽  
Vol 21 (8) ◽  
pp. 2776
Author(s):  
Kang Hyeok Choi ◽  
Changjae Kim
Keyword(s):  
Outer Part ◽  
Calibration Procedure ◽  
Geometric Distortion ◽  
Eye Lens ◽  
Wide Field ◽  
Test Bed ◽  
Self Calibration ◽  
Type Test ◽  
Balanced Distribution ◽  
Fish Eye

The fish-eye lens camera has a wide field of view that makes it effective for various applications and sensor systems. However, it incurs strong geometric distortion in the image due to compressive recording of the outer part of the image. Such distortion must be interpreted accurately through a self-calibration procedure. This paper proposes a new type of test-bed (the AV-type test-bed) that can effect a balanced distribution of image points and a low level of correlation between orientation parameters. The effectiveness of the proposed test-bed in the process of camera self-calibration was verified through the analysis of experimental results from both a simulation and real datasets. In the simulation experiments, the self-calibration procedures were performed using the proposed test-bed, four different projection models, and five different datasets. For all of the cases, the Root Mean Square residuals (RMS-residuals) of the experiments were lower than one-half pixel. The real experiments, meanwhile, were carried out using two different cameras and five different datasets. These results showed high levels of calibration accuracy (i.e., lower than the minimum value of RMS-residuals: 0.39 pixels). Based on the above analyses, we were able to verify the effectiveness of the proposed AV-type test-bed in the process of camera self-calibration.

Improvement in imaging common temporal bone pathologies at 3 T MRI: small structures benefit from a small field of view

2017 ◽  
Vol 72 (3) ◽  
pp. 267.e1-267.e12 ◽  
Author(s):  
M. Schulze ◽  
K. Reimann ◽  
A. Seeger ◽  
U. Klose ◽  
U. Ernemann ◽  
...  
Keyword(s):  
Temporal Bone ◽  
Field Of View ◽  
Small Field ◽  
Small Field Of View
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