scholarly journals EXPERIMENTAL ASSESSMENT OF TECHNIQUES FOR FISHEYE CAMERA CALIBRATION

2015 ◽  
Vol 21 (3) ◽  
pp. 637-651 ◽  
Author(s):  
José Marcato Junior ◽  
Marcus Vinícius Antunes de Moraes ◽  
Antonio Maria Garcia Tommaselli
Keyword(s):  
Mathematical Models ◽  
Solid Angle ◽  
High Accuracy ◽  
Field Of View ◽  
Perspective Projection ◽  
Fisheye Lens ◽  
Close Range ◽  
Fisheye Camera ◽  
Orientation Parameters ◽  
Fisheye Lenses

Abstract:Fisheye lens cameras enable to increase the Field of View (FOV), and consequently they have been largely used in several applications like robotics. The use of this type of cameras in close-range Photogrammetry for high accuracy applications, requires rigorous calibration. The main aim of this work is to present the calibration results of a Fuji Finepix S3PRO camera with Samyang 8mm fisheye lens using rigorous mathematical models. Mathematical models based on Perspective, Stereo-graphic, Equi-distant, Orthogonal and Equi-solid-angle projections were implemented and used in the experiments. The fisheye lenses are generally designed following one of the last four models, and Bower-Samyang 8mm lens is based on Stereo-graphic projection. These models were used in combination with symmetric radial, decentering and affinity distortion models. Experiments were performed to verify which set of IOPs (Interior Orientation Parameters) presented better results to describe the camera inner geometry. Collinearity mathematical model, which is based on perspective projection, presented the less accurate results, which was expected because fisheye lenses are not designed following the perspective projection. Stereo-graphic, Equi-distant, Orthogonal and Equi-solid-angle projections presented similar results even considering that Bower-Samyang fisheye lens was built based on Stereo-graphic projection. The experimental results also demonstrated a small correlation between IOPs and EOPs (Exterior Orientation Parameters) for Bower-Samyang lens.

Modeling Hyperhemispherical Points and Calibrating a Dual-Fish-Eye System for Close-Range Applications

2021 ◽  
Vol 87 (5) ◽  
pp. 375-384
Author(s):  
Letícia Ferrari Castanheiro ◽  
Antonio Maria Garcia Tommaselli ◽  
Adilson Berveglieri ◽  
Mariana Batista Campos ◽  
José Marcato Junior
Keyword(s):  
Comparative Analysis ◽  
Relative Orientation ◽  
Field Of View ◽  
Object Space ◽  
Close Range ◽  
Calibration Techniques ◽  
Orientation Parameters ◽  
Fish Eye

Omnidirectional systems composed of two hyperhemispherical lenses (dual-fish-eye systems) are gaining popularity, but only a few works have studied suitable models for hyperhemispherical lenses and dual-fish-eye calibration. In addition, the effects of using points in the hyperhemispherical field of view in photogrammetric procedures have not been addressed. This article presents a comparative analysis of the fish-eye models (equidistant, equisolid-angle, stereographic, and orthogonal) for hyperhemispherical-lens and dual-fish-eye calibration techniques. The effects of adding points beyond 180° field of view in dual-fish-eye calibration using stability constraints of relative orientation parameters are also assessed. The experiments were performed with the Ricoh Theta dual-fish-eye system, which is composed of fish-eye lenses with a field of view of approximately 190° each. The equisolid-angle model presented the best results in the simultaneous calibration experiments. An accuracy of approximately one pixel in the object space units was achieved, showing the potential of the proposed approach for close-range applications.

Segmentation of Tuberculosis Bacilli Using Watershed Transformation and Fuzzy C-Means

2019 ◽  
Vol 13 (1) ◽  
pp. 9
Author(s):  
Rahadian Kurniawan ◽  
Izzati Muhimmah ◽  
Arrie Kurniawardhani ◽  
Sri Kusumadewi
Keyword(s):  
Microscopic Analysis ◽  
High Accuracy ◽  
Kappa Coefficient ◽  
Field Of View ◽  
Resistant Bacteria ◽  
Screening Process ◽  
Watershed Transformation ◽  
Fuzzy C Means ◽  
Primary Health ◽  
Manual Calculation

The easily transmitted Tuberculosis (TB) disease is attributed to the fact that Mycobacterium Tuberculosis (MTB) bacteria/viruses can be transmitted through the air. One of the methods to screen the TB disease is by reading sputum slides. Sputum slides are colored sputum samples of TB patients placed on microscopic slides. However, TB disease microscopic analysis has some limitations since it requires high accuracy reading and well-trained health personnel to avoid errors in the process of interpretation. Furthermore, the number of TB patients in the Primary Health Care (PHC) and the process of manual calculation of bacteria in a field of view often complicate the decision-making in the screening process conducted by the medical staffs. In this paper, the researchers propose the use of Watershed Transformation and Fuzzy C-Means combination to help solve the problem. The researchers collect the photo shooting of three PHC in Indonesia with 55 images of sputum from different TB patients. The assessed results of the proposed method are compared with the opinions of three Microbiology doctors. The comparison shows Cohen’s Kappa Coefficient value of 0.838. It suggests that the proposed method can detect Acid Resistant Bacteria (ARB) although it needs some improvement to achieve higher accuracy.

Fisheye lens camera based surveillance system for wide field of view monitoring

Optik ◽  
2016 ◽  
Vol 127 (14) ◽  
pp. 5636-5646 ◽  
Author(s):  
Hyungtae Kim ◽  
Jaehoon Jung ◽  
Joonki Paik
Keyword(s):  
Surveillance System ◽  
Field Of View ◽  
Wide Field ◽  
Fisheye Lens ◽  
Wide Field Of View

Design of Mechaless LiDAR Optical System With Large FOV Using Liquid Lens and Fisheye Lens

2018 ◽  
Author(s):  
Hyun Choi ◽  
Wan-Chin Kim
Keyword(s):  
Low Cost ◽  
Autonomous Driving ◽  
Voltage Regulation ◽  
Field Of View ◽  
Fisheye Lens ◽  
Liquid Lens ◽  
Fine Spatial Resolution ◽  
Flash Lidar ◽  
Optical Phased Array ◽  
Measurable Distance

Mechaless LiDAR technology, which does not have a mechanical drive part, has been actively studied in order to increase the reliability of the LiDAR device at low cost and drive environment in order to more actively apply LiDAR technology to autonomous driving. Mechaless LiDAR technology, which has been mainly studied recently, includes 3D Flash LiDAR technology, MEMS mirror utilization method, and OPA (Optical Phased Array). However, these methods have not been developed rapidly as a key technology for achieving autonomous driving due to low stability of driving environment or remarkably low measurable distance and FOV (field of view) compared with mechanical LiDAR. In this study, we investigated the improvement of FOV by using a flux-deflecting liquid lens and a fisheye lens that can achieve fine spatial resolution through continuous voltage regulation. Based on the initial design results, it was examined that the FOV can be secured to 80 ° or more by utilizing a relatively simple fisheye lens composed of only spherical lenses.

On-Orbit Calibration Approach Based on Partial Calibration-Field Coverage for the GF-1/WFV Camera

2019 ◽  
Vol 85 (11) ◽  
pp. 815-827 ◽  
Author(s):  
Mi Wang ◽  
Beibei Guo ◽  
Ying Zhu ◽  
Yufeng Cheng ◽  
Chenhui Nie
Keyword(s):  
High Resolution ◽  
High Accuracy ◽  
Field Of View ◽  
Estimation Methods ◽  
Large Field ◽  
Wide Field ◽  
Optical Remote Sensing ◽  
Calibration Data ◽  
Stereoscopic Images ◽  
Wide Field Of View

The Gaofen-1 (GF1) optical remote sensing satellite is the first in China's series of high-resolution civilian satellites and is equipped with four wide-field-of-view cameras. The cameras work together to obtain an image 800 km wide, with a resolution of 16 m, allowing GF1 to complete a global scan in four days. To achieve high-accuracy calibration of the wide-field-of-view cameras on GF1, the calibration field should have high resolution and broad coverage based on the traditional calibration method. In this study, a GF self-calibration scheme was developed. It uses partial reference calibration data covering the selected primary charge-coupled device to achieve high-accuracy calibration of the whole image. Based on the absolute constraint of the ground control points and the relative constraint of the tie points of stereoscopic images, we present two geometric calibration models based on paired stereoscopic images and three stereoscopic images for wide-field-of-view cameras on GF1, along with corresponding stepwise internal-parameter estimation methods. Our experimental results indicate that the internal relative accuracy can be guaranteed after calibration. This article provides a new approach that enables large-field-of-view optical satellites to achieve high-accuracy calibration based on partial calibration-field coverage.

Mathematical Models for the "Schmalhgausent Law"

2003 ◽  
Vol 11 (03) ◽  
pp. 245-264 ◽  
Author(s):  
Georgy P. Karev ◽  
Faina S. Berezovskaya
Keyword(s):  
Mathematical Models ◽  
Empirical Data ◽  
Empirical Formula ◽  
Polygonal Line ◽  
High Accuracy ◽  
Logarithmic Scale ◽  
Tree Stand ◽  
Double Logarithmic Scale ◽  
Biological Objects

The empirical formula of growth (decrease) of biological objects, corresponding to polygonal line in double logarithmic scale is discussed. Leslie-type models producing solutions similar to some specific cases of this formula (including logistic-like curve) are studied. As an example, a model of tree stand self-thinning is derived and investigated; the model allows fitting empirical data with high accuracy.

Research on a Digital Close-Range Photogrammetric Bridge Deflection Measurement System

2013 ◽  
Vol 392 ◽  
pp. 734-737
Author(s):  
Wan Ting Wang ◽  
Han Bing Liu
Keyword(s):  
Program Development ◽  
Measurement System ◽  
Measurement Method ◽  
Field Tests ◽  
High Accuracy ◽  
Theoretical Description ◽  
System Configuration ◽  
Deflection Measurement ◽  
Analysis Process ◽  
Close Range

This paper introduces a new close-range photogrammetric bridge deflection non-contact measurement method that has high accuracy and efficiency, and can be conveniently used by engineers without help from professional surveyors. After a general theoretical description (analysis process and program development) of a photogrammetric bridge deflection measurement method, the system configuration is introduced and the application is verified through the laboratory and field tests.

scholarly journals Beyond All-Sky: Assessing Ecological Light Pollution Using Multi-Spectral Full-Sphere Fisheye Lens Imaging

2019 ◽  
Vol 5 (4) ◽  
pp. 46 ◽  
Author(s):  
Andreas Jechow ◽  
Christopher Kyba ◽  
Franz Hölker
Keyword(s):  
Solid Angle ◽  
Vertical Plane ◽  
Digital Camera ◽  
Field Work ◽  
Color Temperature ◽  
Light Pollution ◽  
Night Time ◽  
Full Spectrum ◽  
Fisheye Lens ◽  
Practical Procedure

Artificial light at night is a novel anthropogenic stressor. The resulting ecological light pollution affects a wide breadth of biological systems on many spatio-temporal scales, from individual organisms to communities and ecosystems. However, a widely-applicable measurement method for nocturnal light providing spatially resolved full-spectrum radiance over the full solid angle is still missing. Here, we explain the first step to fill this gap, by using a commercial digital camera with a fisheye lens to acquire vertical plane multi-spectral (RGB) images covering the full solid angle. We explain the technical and practical procedure and software to process luminance and correlated color temperature maps and derive illuminance. We discuss advantages and limitations and present data from different night-time lighting situations. The method provides a comprehensive way to characterize nocturnal light in the context of ecological light pollution. It is affordable, fast, mobile, robust, and widely-applicable by non-experts for field work.

Error analysis and optimal design of reduction relay lens for field of view stitching applications

Sensor Review ◽  
2021 ◽  
Vol 41 (1) ◽  
pp. 87-92
Author(s):  
Xinjie Zhang ◽  
Fansen Kong ◽  
Zhiyuan Gu ◽  
Xiao Shen
Keyword(s):  
Remote Sensing ◽  
Image Quality ◽  
High Accuracy ◽  
Structure Design ◽  
Reduction Ratio ◽  
Field Of View ◽  
Machining Accuracy ◽  
Optical Remote Sensing ◽  
Optical Elements ◽  
Content Type

Purpose FOV splicing optical remote sensing instruments have a strict requirement for the focal length consistency of the lens. In conventional optical-mechanical structure design, each optical element is equally distributed with high accuracy and everyone must have a high machining and assembly accuracy. For optical remote sensors with a large number of optical elements, this design brings great difficulties to lens manufacture and alignment. Design/methodology/approach Taking the relay lens in an optical remote sensing instrument with the field of view splicing as an example, errors of the system are redistributed to optical elements. Two optical elements, which have the greatest influence on modulation transfer function (MTF) of the system are mounted with high accuracy centering and the other elements are fixed by gland ring with common machining accuracy. The reduction ratio consistency difference among lenses is compensated by adjusting the optical spacing between the two elements. Findings Based on optical system simulation analysis, the optimized structure can compensate for the difference of reduction ratio among lens by grinding the washer thickness in the range of ±0.37 mm. The test data for the image quality of the lens show that the MTF value declined 0.043 within ±0.4 mm of space change between two barrels. The results indicate that the reduction ratio can be corrected by adjusting the washer thickness and the image quality will not obviously decline. Originality/value This paper confirms that this work is original and has not been published elsewhere nor is it currently under consideration for publication elsewhere. In this paper, the optimum structural design of the reduction relay lens for the field of view stitching applications is reported. The method of adjusting washer thickness is applied to compensate for the reduction ratio consistency difference of lenses. The optimized structure also greatly reduces the difficulty of lenses manufacture, alignment and improves the efficiency of assembly.

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