A Comparison of Two Different Approaches to Camera Calibration in LSDM Photogrammetric Systems

2014 ◽  
Author(s):  
Ou Bai ◽  
Fiorenzo Franceschini ◽  
Maurizio Galetto ◽  
Luca Mastrogiacomo ◽  
Domenico A. Maisano
Keyword(s):  
Camera Calibration ◽  
Large Scale ◽  
Focal Length ◽  
Calibration Procedure ◽  
Optical Systems ◽  
Multiple Cameras ◽  
Dimensional Metrology ◽  
Distortion Parameters ◽  
Length Distortion

Large Scale Dimensional Metrology (LSDM) is a branch of metrology that deals with the measurement of objects with dimensions in the order of several meters. Optical systems, relying on the use of multiple cameras and photogrammetric techniques, are among the most used instruments in this field. These systems require a preliminary calibration procedure to determine some essential parameters, such as camera positions and orientations, focal length, distortion parameters, etc. A structured comparison between two different approaches to camera calibration is herein discussed.

scholarly journals CAMERA CONSTANT IN THE CASE OF TWO MEDIA PHOTOGRAMMETRY

2015 ◽  
Vol XL-5/W5 ◽  
pp. 1-6 ◽  
Author(s):  
P. Agrafiotis ◽  
A. Georgopoulos
Keyword(s):  
Refractive Index ◽  
Camera Calibration ◽  
Focal Length ◽  
Calibration Procedure ◽  
Water Salinity ◽  
Clean Water ◽  
Object Distance ◽  
Calibration Methods ◽  
The One ◽  
Probable Relation

Refraction is the main cause of geometric distortions in the case of two media photogrammetry. However, this effect cannot be compensated and corrected by a suitable camera calibration procedure (Georgopoulos and Agrafiotis, 2012). In addition, according to the literature (Lavest et al. 2000), when the camera is underwater, the effective focal length is approximately equal to that in the air multiplied by the refractive index of water. This ratio depends on the composition of the water (salinity, temperature, etc.) and usually ranges from 1.10 to 1.34. It seems, that in two media photogrammetry, the 1.33 factor used for clean water in underwater cases does not apply and the most probable relation of the effective camera constant to the one in air is depending of the percentages of air and water within the total camera-to-object distance. This paper examines this relation in detail, verifies it and develops it through the application of calibration methods using different test fields. In addition the current methodologies for underwater and two-media calibration are mentioned and the problem of two-media calibration is described and analysed.

scholarly journals 3D Reconstruction of Bird Flight using a Single Video Camera

2018 ◽  
Author(s):  
M.V. Srinivasan ◽  
H.D. Vo ◽  
I. Schiffner
Keyword(s):  
Prior Knowledge ◽  
Camera Calibration ◽  
Video Camera ◽  
Calibration Procedure ◽  
Three Dimensions ◽  
Multiple Cameras ◽  
Bird Flight ◽  
Video Cameras ◽  
Video Frames ◽  
Alternative Approach

ABSTRACTVideo cameras are finding increasing use in the study and analysis of bird flight over short ranges. However, reconstruction of flight trajectories in three dimensions typically requires the use of multiple cameras and elaborate calibration procedures. We present an alternative approach that uses a single video camera and a simple calibration procedure for the reconstruction of such trajectories. The technique combines prior knowledge of the bird’s wingspan with a camera calibration procedure that needs to be used only once in the system’s lifetime. The system delivers the exact 3D coordinates of the bird at the time of every full wing extension, and uses interpolated height estimates to compute the 3D positions of the bird in the video frames between successive wing extensions. The system is inexpensive, compact and portable, and can be easily deployed in the laboratory as well as the field.

scholarly journals Camera Calibration using the Damped Bundle Adjustment Toolbox

2014 ◽  
Vol II-5 ◽  
pp. 89-96 ◽  
Author(s):  
N. Börlin ◽  
P. Grussenmeyer
Keyword(s):  
Camera Calibration ◽  
Focal Length ◽  
Standard Procedure ◽  
Calibration Procedure ◽  
Bundle Adjustment ◽  
Data Sets ◽  
Calibration Data ◽  
Initial Values ◽  
Convergence Results ◽  
Highly Correlated

Camera calibration is one of the fundamental photogrammetric tasks. The standard procedure is to apply an iterative adjustment to measurements of known control points. The iterative adjustment needs initial values of internal and external parameters. In this paper we investigate a procedure where only one parameter &ndash; the focal length is given a specific initial value. The procedure is validated using the freely available Damped Bundle Adjustment Toolbox on five calibration data sets using varying narrow- and wide-angle lenses. <br><br> The results show that the Gauss-Newton-Armijo and Levenberg-Marquardt-Powell bundle adjustment methods implemented in the toolbox converge even if the initial values of the focal length are between 1/2 and 32 times the true focal length, even if the parameters are highly correlated. Standard statistical analysis methods in the toolbox enable manual selection of the lens distortion parameters to estimate, something not available in other camera calibration toolboxes. <br><br> A standardised camera calibration procedure that does not require any information about the camera sensor or focal length is suggested based on the convergence results. <br><br> The toolbox source and data sets used in this paper are available from the authors.

scholarly journals P/Halley: The Disconnection Event of 1986 April 11

1988 ◽  
Vol 98 ◽  
pp. 155-157 ◽  
Author(s):  
P.M. Bergé ◽  
G. Mahoux ◽  
A.C. Levasseur-Regourd
Keyword(s):  
Southern Hemisphere ◽  
Large Scale ◽  
Focal Length ◽  
La Réunion ◽  
Structure Dynamics ◽  
Plasma Tail

This work was carried out by an expedition organized by the S.A.F. in 1986 April to La Réunion. The aim was to observe and photograph P/Halley, within the framework of IHW, as part of the Island Network in the southern hemisphere. To be more precise, our work consisted of studying large-scale phenomena: the structure, dynamics and possible disconnection events in the plasma tail. We were lucky enough to observe one of the latter on the night of April 11/12, and describe it here.For the Island Network, IHW had a number of Schmidt telescopes (Celestron 8). One was lent to the S.A.F. and this is what we used. This telescope has a focal ratio of 1.5, with a 200-mm (8-inch) objective and 300-mm focal length. We used only Kodak TP2415 film, hypersensitized in forming gas (24h at 60°C).

scholarly journals Extrinsic Camera Calibration with Line-Laser Projection

Sensors ◽  
2021 ◽  
Vol 21 (4) ◽  
pp. 1091
Author(s):  
Izaak Van Crombrugge ◽  
Rudi Penne ◽  
Steve Vanlanduit
Keyword(s):  
Camera Calibration ◽  
Real World ◽  
Large Scale ◽  
State Of The Art ◽  
Bundle Adjustment ◽  
Field Of View ◽  
Extrinsic Calibration ◽  
Practical Procedure ◽  
Partial Overlap

Knowledge of precise camera poses is vital for multi-camera setups. Camera intrinsics can be obtained for each camera separately in lab conditions. For fixed multi-camera setups, the extrinsic calibration can only be done in situ. Usually, some markers are used, like checkerboards, requiring some level of overlap between cameras. In this work, we propose a method for cases with little or no overlap. Laser lines are projected on a plane (e.g., floor or wall) using a laser line projector. The pose of the plane and cameras is then optimized using bundle adjustment to match the lines seen by the cameras. To find the extrinsic calibration, only a partial overlap between the laser lines and the field of view of the cameras is needed. Real-world experiments were conducted both with and without overlapping fields of view, resulting in rotation errors below 0.5°. We show that the accuracy is comparable to other state-of-the-art methods while offering a more practical procedure. The method can also be used in large-scale applications and can be fully automated.

Camera Calibration Method Based on Circle Plane Board

2013 ◽  
Vol 475-476 ◽  
pp. 184-187
Author(s):  
Wen Guo Li ◽  
Shao Jun Duan
Keyword(s):  
Camera Calibration ◽  
Calibration Method ◽  
Lens Distortion ◽  
Edge Extraction ◽  
Circle Plane ◽  
Circle Centre ◽  
Extraction Algorithm ◽  
Calibration Algorithm ◽  
Characteristic Points ◽  
Distortion Parameters

We present a camera calibration method based on circle plane board. The centres of circles on plane are regarded as the characteristic points, which are used to implement camera calibration. The proposed calibration is more accurate than many previous calibration algorithm because of the merit of the coordinate of circle centre being obtained from thousand of of edge pionts of ellipse, which is very reliable to image noise caused by edge extraction algorithm. Experiments shows the proposed algorithm can obtain high precise inner parameters, and lens distortion parameters.

Universal method for determining the focal length of optical systems by moire deflectometry

1988 ◽  
Vol 27 (8) ◽  
pp. 1383 ◽  
Author(s):  
Eliezer Keren ◽  
Kathi M. Kreske ◽  
Oded Kafri
Keyword(s):  
Focal Length ◽  
Optical Systems ◽  
Universal Method ◽  
Moiré Deflectometry

Large-Scale Camera Calibration with Neural Network

2011 ◽  
Vol 31 (4) ◽  
pp. 0415001
Author(s):  
田震 Tian Zhen ◽  
张玘 Zhang Qi ◽  
熊九龙 Xiong Jiulong ◽  
王国超 Wang Guochao
Keyword(s):  
Neural Network ◽  
Camera Calibration ◽  
Large Scale

Large-Scale Dimensional Metrology: The New Paradigm of Distributed Systems

2011 ◽  
pp. 1-22
Author(s):  
Fiorenzo Franceschini ◽  
Maurizio Galetto ◽  
Domenico Maisano ◽  
Luca Mastrogiacomo ◽  
Barbara Pralio
Keyword(s):  
Distributed Systems ◽  
Large Scale ◽  
New Paradigm ◽  
Dimensional Metrology

scholarly journals 3D DIGITAL RECONSTRUCTION BASED ON ARCHIVED TERRESTRIAL PHOTOGRAPHS FROM METRIC CAMERAS

2019 ◽  
Vol 59 (4) ◽  
pp. 384-398 ◽  
Author(s):  
Zdeněk Poloprutský ◽  
Marek Fraštia ◽  
Marián Marčiš
Keyword(s):  
Image Processing ◽  
Digital Image Processing ◽  
Structure From Motion ◽  
Focal Length ◽  
Lens System ◽  
Heritage Preservation ◽  
Unknown Parameters ◽  
Digital Reconstruction ◽  
Landscape Preservation ◽  
Distortion Parameters

The paper deals with the possibilities and limitations of the image processing of digitalized terrestrial photographs from analogue metric cameras. By the end of the 20th century, analogue metric cameras such as Zeiss UMK were used for documentation purposes in the fields of industrial and investment construction, nature and landscape preservation, heritage preservation, etc. Currently, the collections of photographs are stored at specialized archives of many different institutions, such as libraries, museums, universities, etc. These sets of photographs provide a material background for a 3D digital reconstruction of a subject of interest at the time of taking the photographs. The digital image processing of old photographs may be more difficult due to unknown parameters of the used camera, such as the focal length, image coordinates of the fiducial marks and distortion parameters of the lens system, etc. In this case, it may be difficult to process these photographs in a photogrammetric software. The paper presents a methodology for the digital photogrammetric processing of analogue terrestrial photographs. The data processing is based on the parameters of the used metric cameras, which are described in their calibration reports. The image processing was tested in two commercial photogrammetric software tools that utilize the technology of Structure-from-Motion (SfM) or multiimage intersection photogrammetry to process image datasets.

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