scholarly journals EXPERIMENTS ON CALIBRATING TILT-SHIFT LENSES FOR CLOSE-RANGE PHOTOGRAMMETRY

2016 ◽  
Vol XLI-B5 ◽  
pp. 99-105 ◽  
Author(s):  
E. Nocerino ◽  
F. Menna ◽  
F. Remondino ◽  
J.-A. Beraldin ◽  
L. Cournoyer ◽  
...  
Keyword(s):  
Optical Axis ◽  
National Research Council ◽  
Image Plane ◽  
Limiting Factors ◽  
Depth Of Field ◽  
Small Object ◽  
Digital Cameras ◽  
Close Range Photogrammetry ◽  
Object Distance ◽  
Close Range

One of the strongest limiting factors in close range photogrammetry (CRP) is the depth of field (DOF), especially at very small object distance. When using standard digital cameras and lens, for a specific camera – lens combination, the only way to control the extent of the zone of sharp focus in object space is to reduce the aperture of the lens. However, this strategy is often not sufficient; moreover, in many cases it is not fully advisable. In fact, when the aperture is closed down, images lose sharpness because of diffraction. Furthermore, the exposure time must be lowered (susceptibility to vibrations) and the ISO increased (electronic noise may increase). In order to adapt the shape of the DOF to the subject of interest, the Scheimpflug rule is to be applied, requiring that the optical axis must be no longer perpendicular to the image plane. Nowadays, specific lenses exist that allow inclining the optical axis to modify the DOF: they are called tilt-shift lenses. In this paper, an investigation on the applicability of the classic photogrammetric model (pinhole camera coupled with Brown’s distortion model) to these lenses is presented. Tests were carried out in an environmentally controlled metrology laboratory at the National Research Council (NRC) Canada and the results are hereafter described in detail.

scholarly journals EXPERIMENTS ON CALIBRATING TILT-SHIFT LENSES FOR CLOSE-RANGE PHOTOGRAMMETRY

2016 ◽  
Vol XLI-B5 ◽  
pp. 99-105 ◽  
Author(s):  
E. Nocerino ◽  
F. Menna ◽  
F. Remondino ◽  
J.-A. Beraldin ◽  
L. Cournoyer ◽  
...  
Keyword(s):  
Optical Axis ◽  
National Research Council ◽  
Image Plane ◽  
Limiting Factors ◽  
Depth Of Field ◽  
Small Object ◽  
Digital Cameras ◽  
Close Range Photogrammetry ◽  
Object Distance ◽  
Close Range

One of the strongest limiting factors in close range photogrammetry (CRP) is the depth of field (DOF), especially at very small object distance. When using standard digital cameras and lens, for a specific camera – lens combination, the only way to control the extent of the zone of sharp focus in object space is to reduce the aperture of the lens. However, this strategy is often not sufficient; moreover, in many cases it is not fully advisable. In fact, when the aperture is closed down, images lose sharpness because of diffraction. Furthermore, the exposure time must be lowered (susceptibility to vibrations) and the ISO increased (electronic noise may increase). In order to adapt the shape of the DOF to the subject of interest, the Scheimpflug rule is to be applied, requiring that the optical axis must be no longer perpendicular to the image plane. Nowadays, specific lenses exist that allow inclining the optical axis to modify the DOF: they are called tilt-shift lenses. In this paper, an investigation on the applicability of the classic photogrammetric model (pinhole camera coupled with Brown’s distortion model) to these lenses is presented. Tests were carried out in an environmentally controlled metrology laboratory at the National Research Council (NRC) Canada and the results are hereafter described in detail.

scholarly journals DoF-Dependent and Equal-Partition Based Lens Distortion Modeling and Calibration Method for Close-Range Photogrammetry

Sensors ◽  
2020 ◽  
Vol 20 (20) ◽  
pp. 5934
Author(s):  
Xiao Li ◽  
Wei Li ◽  
Xin’an Yuan ◽  
Xiaokang Yin ◽  
Xin Ma
Keyword(s):  
Optical Axis ◽  
Focal Length ◽  
Calibration Method ◽  
Depth Of Field ◽  
Model Parameters ◽  
Lens Distortion ◽  
Camera Model ◽  
Distortion Model ◽  
Manual Adjustment ◽  
Close Range

Lens distortion is closely related to the spatial position of depth of field (DoF), especially in close-range photography. The accurate characterization and precise calibration of DoF-dependent distortion are very important to improve the accuracy of close-range vision measurements. In this paper, to meet the need of short-distance and small-focal-length photography, a DoF-dependent and equal-partition based lens distortion modeling and calibration method is proposed. Firstly, considering the direction along the optical axis, a DoF-dependent yet focusing-state-independent distortion model is proposed. By this method, manual adjustment of the focus and zoom rings is avoided, thus eliminating human errors. Secondly, considering the direction perpendicular to the optical axis, to solve the problem of insufficient distortion representations caused by using only one set of coefficients, a 2D-to-3D equal-increment partitioning method for lens distortion is proposed. Accurate characterization of DoF-dependent distortion is thus realized by fusing the distortion partitioning method and the DoF distortion model. Lastly, a calibration control field is designed. After extracting line segments within a partition, the de-coupling calibration of distortion parameters and other camera model parameters is realized. Experiment results shows that the maximum/average projection and angular reconstruction errors of equal-increment partition based DoF distortion model are 0.11 pixels/0.05 pixels and 0.013°/0.011°, respectively. This demonstrates the validity of the lens distortion model and calibration method proposed in this paper.

scholarly journals USING SMART PHONES FOR DEFORMATIONS MEASUREMENTS OF STRUCTURES

2017 ◽  
Vol 43 (2) ◽  
pp. 66-72 ◽  
Author(s):  
Khalid L. A. EL-ASHMAWY
Keyword(s):  
Least Squares ◽  
Smart Phones ◽  
Digital Cameras ◽  
Object Space ◽  
Close Range Photogrammetry ◽  
Variable Displacement ◽  
Close Range ◽  
Displacement Transducers ◽  
Better Than

The present work tests the suitability of using the digital cameras of smart phones for close range photogrammetry applications. For this purpose two cameras of smart phones Lumia 535 and Lumia 950 XL were used. The resolutions of the two cameras are 5 and 20 Mpixels respectively. The tests consist of (a) self calibration of the two cameras, (b) the implementation of close-range photogrammetry using the cameras of the two smart phones, theodolite intersection with LST method, and linear variable displacement transducers (LVDTs) for the measurement of vertical deflections, and (c) accuracy of photogrammetric determination of object space coordinates. The results of using Lumia 950 XL are much better than using Lumia 535 and are better or comparable to the results of theodolite intersection with least squares technique (LST). Finally, it can be stated that the digital cameras of smart phones are suitable for close range photogrammetry applications according to accuracy, costs and flexibility.

3D Model Reconstruction Based on Close-Range Photogrammetry

2012 ◽  
Vol 263-266 ◽  
pp. 2393-2398
Author(s):  
Wei Zeng ◽  
Si Dong Zhong ◽  
Yuan Yao ◽  
Zhen Feng Shao
Keyword(s):  
High Precision ◽  
3D Model ◽  
Three Dimensional ◽  
Light Detection And Ranging ◽  
Model Reconstruction ◽  
Close Range Photogrammetry ◽  
Object Distance ◽  
3D Model Reconstruction ◽  
Key Technologies ◽  
Close Range

Close-range photogrammetry is a technique of calculating the location, size and shape of measured object by photography whose object distance is generally not greater than 300 meters. Three-dimensional (3D) model reconstruction based on close-range photogrammetry has higher efficiency than that based on Light Detection And Ranging (LiDAR) technique since acquiring texture data simultaneously. This technology reduces the consuming time of 3D model reconstruction, while ensuring high precision. In this paper, processes and key technologies of 3D model reconstruction based on portable close-range photogrammetry are provided, and it feasibility of the technology is verified via taking Taizhou TV Tower as an example.

scholarly journals IMPLEMENTATION OF CLOSE RANGE PHOTOGRAMMETRY USING MODERN NON-METRIC DIGITAL CAMERAS FOR ARCHITECTURAL DOCUMENTATION

2021 ◽  
Vol 47 (1) ◽  
pp. 45-53
Author(s):  
Mariem A. Elhalawani ◽  
Zaki M. Zeidan ◽  
Ashraf A. A. Beshr
Keyword(s):  
3D Model ◽  
Historical Research ◽  
Control Points ◽  
Digital Cameras ◽  
Flatbed Scanner ◽  
Historical Structures ◽  
Close Range Photogrammetry ◽  
Close Range ◽  
Architectural Documentation

The development of applied geodetic techniques for mapping and documentation of historical structures, buildings and sites is an important and vital purpose for contribution of any recording of cultural heritage for any country such as Egypt. This is done to preserve and restore any valuable architectural or other cultural monument, as a support to architectural, archaeological and other art-historical research throughout the ages. The purpose of this paper is to use close range photogrammetry technique (CRP) to reconstruct 3D model of architectural and historical mosque facade and comparing the accuracy of using digital commercial non-metric cameras with different resolutions and metric camera with flatbed scanner and photogrammetric scanner for architectural building documentation. El-Nasr Mosque façade in Mansoura city, Egypt was chosen as a case study in this paper. At first, twenty five points were selected at mosque façade at different elevations and distributed at different façade surfaces and observed using total station. Some of these points were selected as control points and the others were selected as check points to validate the results. Effect of control point’s number on image processing and analysis is also studied. Three cameras positions were selected for imaging to get the full details of mosque façade. Close range Digital Workstation (CDW) program was used for processing and analysis of multiple images. The results are indicated that close range photogrammetry using metric camera with photogrammetry scanner instead of flatbed scanner in technique is accurate enough to be beneficial in 3D architectural building documentation. Digital cameras with CRP technique give up different accuracy that depends mainly on the resolution of cameras and camera specifications.

Study of close-Range Photogrammetric Method Using Ordinary Digital Camera

2011 ◽  
Vol 110-116 ◽  
pp. 4337-4342
Author(s):  
Ying Dan Mao
Keyword(s):  
Image Processing ◽  
Digital Imaging ◽  
Digital Camera ◽  
Mapping Method ◽  
Digital Cameras ◽  
Basic Principles ◽  
Progressive Development ◽  
Close Range Photogrammetry ◽  
Close Range ◽  
Photogrammetric Method

With the progressive development of photogrammetric technology, the digital photogrammetric method based on the basic principles of digital imaging and photogrammetry has replaced the traditional photogrammetric mapping method and has been widely promoted and applied. In this paper, it studies further the issues about the image processing and photogrammetric algorithms of common digital cameras based on some research results in the traditional field of close-range photogrammetry, and verifies with actual examples the application of using digital cameras to implement the close-range photogrammetric method to engineering is feasible.

scholarly journals Digital Model in Close-Range Photogrammetry Using a Smartphone Camera

2021 ◽  
Vol 318 ◽  
pp. 04005
Author(s):  
Tariq N. Ataiwe ◽  
Israa Hatem ◽  
Hisham M. J. Al Sharaa
Keyword(s):  
Camera Calibration ◽  
3D Model ◽  
Accuracy Assessment ◽  
Low Cost ◽  
Calibration Model ◽  
Digital Cameras ◽  
Close Range Photogrammetry ◽  
Close Range ◽  
Chessboard Pattern ◽  
Image Orientation

Smartphones recently expanded the potential for low-cost close-range photogrammetry for 3D modeling. They enable the simultaneous collection of large amounts of data for a variety of requirements. It is possible to calculate image orientation elements and triangular coordinates in phases as in Relative and Absolute image orientation. This study demonstrates the photogrammetric 3D reconstruction approach that performs on tablets and smartphones as well. Images are taken with smartphone cameras of iPhone 6 and then calibrated automatically using normal calibration model for photogrammetry and computer vision on a PC, depend on Agisoft Lens add-on that imbedded in Agisoft program, and MATLAB camera calibration Toolbox, and by using an oriented bunch of images of chessboard pattern for large point cloud-based picture using matching. The camera calibration results indicate that the calibration processing routines pass without any error, and the accuracy of estimated IOPs was convenient compared with non-metric digital cameras and are more accurate in Agisoft Lens in terms of standard error. For the 3D model, 435 cameras were used, 428 cameras located from 435 are aligned in two photogrammetric software, Agisoft PhotoScan, and LPS. The number of tie points that are used in LPS is 10 tie points, and 4 control points which used to estimate the EOPs, and the number of tie points that are regenerated in Agisoft PhotoScan were 135.605 points, the number of Dense cloud 3,716,912 points are generated, for 3D model a number of 316,253 faces are generated, after processing the tiled model generated (6 levels, 1.25 cm/pix), the generated DEM having (2136×1774/pix), the dimensions of the generated high-resolution orthomosaic are (5520×4494, 4.47 cm/pix). For accuracy assessment, the Xerr. = 0.292 m, Yerr. = 0.38577 m, Zerr.= 0.2889 m, and the total RMS = 0.563 m in the estimated locations of the exterior orientation parameters.

scholarly journals Accuracy Assessment of Various Resolutions Digital Cameras For Close Range Photogrammetry Applications

2018 ◽  
Vol 24 (9) ◽  
pp. 78 ◽  
Author(s):  
Jasim Ahmed Ali AL-Baghdadi ◽  
Hassan Ali Alizze ◽  
Kasim Abed AL-Hussein
Keyword(s):  
Indoor Environment ◽  
Accuracy Assessment ◽  
3D Models ◽  
Outdoor Environment ◽  
Digital Cameras ◽  
Object Distance ◽  
Close Range ◽  
Precise Relationship ◽  
Indoor And Outdoor

Due to the great evolution in digital commercial cameras, several studies have addressed the using of such cameras in different civil and close-range applications such as 3D models generation. However, previous studies have not discussed a precise relationship between a camera resolution and the accuracy of the models generated based on images of this camera. Therefore the current study aims to evaluate the accuracy of the derived 3D buildings models captured by different resolution cameras. The digital photogrammetric methods were devoted to derive 3D models using the data of various resolution cameras and analyze their accuracies. This investigation involves selecting three different resolution cameras (low, medium and high) and evaluating their calibration accuracies. Assessing the accuracy of the three selected cameras in capturing indoor and outdoor objects; and analyzing the accuracy and the quality of the produced models. The study revealed that:1) It is recommended to use the photos of a high-resolution camera for producing precise 3D models of objects in the outdoor environment especially when the camera/object distance is more than 40 m because the accuracy of the  produced models can be  precise (RMSE ±10.36mm) with excellent quality; 2) The Low-resolution camera can be utilised to produce adequate 3D models of object in the indoor environment (RMSE ±6.32mm) especially when the camera/object distance is less than 40 m.  

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