On the Use of Nonmetric Cameras in Analytical Close-Range Photogrammetry

1982 ◽  
Vol 36 (3) ◽  
pp. 259-279 ◽  
Author(s):  
C.S. Fraser
Keyword(s):  
Analytical Data ◽  
High Accuracy ◽  
Bundle Adjustment ◽  
Mixed Block ◽  
Type Method ◽  
Close Range Photogrammetry ◽  
Self Calibration ◽  
Reduction Techniques ◽  
Accuracy And Precision ◽  
Close Range

Analytical data reduction techniques have facilitated the use of nonmetric, amateur cameras in applications of precision photogrammetry. This paper discusses the analytical restitution of close-range nonmetric imagery. Initially, aspects of the mathematical formulations of both the self-calibrating bundle adjustment and sequential DLT-type methods are reviewed and statistical considerations are outlined. A self-calibration approach using mixed block- and photo-invariant additional parameters is proposed, and an experiment conducted to test the accuracy and precision of this technique is detailed. The experiment involved the multistation phototriangulation of nonmetric Hasselblad 500 ELM images, using both self-calibration and a DLT-type method. Relative accuracies in the object space were found to be of the order of 1:10 000 and higher for the former approach and 1:6000 for the latter. Further results of this experiment, which lend weight to the contention that nonmetric cameras are capable of producing results of high accuracy, are discussed and general conclusions are drawn.

scholarly journals Close-range photogrammetry with spherical panoramas for mapping spatial location and measuring diameters of trees under forest canopies

2019 ◽  
Vol 49 (8) ◽  
pp. 865-874
Author(s):  
Mei-Kuei Lu ◽  
Tzeng Yih Lam ◽  
Bo-Hao Perng ◽  
Ho-Tung Lin
Keyword(s):  
Spatial Location ◽  
Horizontal Distance ◽  
Camera Model ◽  
Estimation Errors ◽  
Forest Canopies ◽  
Close Range Photogrammetry ◽  
Accuracy And Precision ◽  
Close Range ◽  
Alternative Measurement ◽  
Individual Trees

Measurement of tree attributes is important to collect information for forest management. Close-range photogrammetry with spherical panoramas has seen very little development and applications compared with aerial photography. This study develops methods to extract azimuth, horizontal distance, diameter at breast height, and upper stem diameters of individual trees from spherical panoramas based on (i) the trigonometry principle (TRIGO), (ii) the TRIGO corrected for terrain slope (TRIGOSLP), and (iii) the pinhole camera model (PINHOLE). Twenty-three horizontal point sample plots were randomly established in plantations in Taiwan, for a sample size of 486 trees. Results showed that tree azimuth was accurately and precisely estimated. TRIGO performed the worst in accuracy and precision for all other tree attributes. TRIGOSLP improved the results of TRIGO but had large estimation errors. PINHOLE achieved the best overall precision for all other tree attributes but was slightly inaccurate for estimating upper stem diameters. PINHOLE requires approaching a tree to attach a target of known size but has the ability to extract an almost continuous set of upper stem diameters from the tree, which could improve estimation of tree volume. Thus, PINHOLE could potentially be an alternative measurement system for hard-to-measure tree attributes.

Strain Measurement for Sheet Metal Forming Based on Close Range Photogrammetry

2013 ◽  
Vol 475-476 ◽  
pp. 148-155 ◽  
Author(s):  
Da Cheng Li ◽  
Jin Liang ◽  
Hao Hu ◽  
Zheng Zong Tang ◽  
Xiang Guo ◽  
...  
Keyword(s):  
Sheet Metal ◽  
Sheet Metal Forming ◽  
Metal Forming ◽  
Strain Measurement ◽  
Bundle Adjustment ◽  
Surface Strain ◽  
Forming Process ◽  
Epipolar Constraint ◽  
Close Range Photogrammetry ◽  
Close Range

To improve efficiency and automation of the 3D full-field surface strain measurement for sheet metal forming, a new grid strain measuring scheme was developed based on the close-range photogrammetry technology. A Local Canny Detector algorithm was proposed for grid nodes and coded targets detection. A 10-parameters nonlinear camera model and the bundle adjustment algorithm were used to optimize the calibration parameters. A multi-epipolar constraint method was employed for grid node matching. Finally, the surface strains were calculated according to the changes of the grid sizes. To evaluate the performance of the proposed scheme, a stamping forming experiment was conducted. Experimental results show that the scheme can provide a non-contact, intuitive and effective solution for strain measurement in sheet metal forming process.

scholarly journals A SIMULATION TOOL ASSISTING THE DESIGN OF A CLOSE RANGE PHOTOGRAMMETRY SYSTEM FOR THE SARDINIA RADIO TELESCOPE

2016 ◽  
Vol III-5 ◽  
pp. 113-120 ◽  
Author(s):  
F. Buffa ◽  
A. Pinna ◽  
G. Sanna
Keyword(s):  
Radio Telescope ◽  
Active Surface ◽  
Optimal Shape ◽  
Bundle Adjustment ◽  
Simulation Tool ◽  
Simulation Environment ◽  
Close Range Photogrammetry ◽  
Large Structures ◽  
Close Range ◽  
Realistic Images

The Sardinia Radio Telescope (SRT) is a 64 m diameter antenna, whose primary mirror is equipped with an active surface capable to correct its deformations by means of a thick network of actuators. Close range photogrammetry (CRP) was used to measure the self-load deformations of the SRT primary reflector from its optimal shape, which are requested to be minimized for the radio telescope to operate at full efficiency. In the attempt to achieve such performance, we conceived a near real-time CRP system which requires the cameras to be installed in fixed positions and at the same time to avoid any interference with the antenna operativeness. The design of such system is not a trivial task, and to assist our decision we therefore developed a simulation pipeline to realistically reproduce and evaluate photogrammetric surveys of large structures. The described simulation environment consists of (i) a detailed description of the SRT model, included the measurement points and the camera parameters, (ii) a tool capable of generating realistic images accordingly to the above model, and (iii) a self-calibrating bundle adjustment to evaluate the performance in terms of RMSE of the camera configurations.

Photogrammetric Method with Distance Constraint for Profile of Inflatable Space Antenna

2008 ◽  
Vol 381-382 ◽  
pp. 313-316 ◽  
Author(s):  
Wen Yi Deng ◽  
Ming Li Dong ◽  
Nai Guang Lu ◽  
Y.Q. Wang
Keyword(s):  
Optimal Solution ◽  
Bundle Adjustment ◽  
Distance Constraint ◽  
Space Antenna ◽  
Close Range Photogrammetry ◽  
Flexible Surface ◽  
Close Range ◽  
Photogrammetric Method ◽  
Two Parameters ◽  
Measuring Force

The inflatable space antenna is gradually used in various spacecrafts because it is portable and foldaway. It is usually made of thin-film materials and has a flexible surface, so that measuring force is not tolerable in measurement process. Close-range photogrammetry is considered as an optimal solution because of its advantages of non-contact operation and fast data acquisition. To improve measuring precision, a method combining bundle adjustment algorithm and the distance constraint is presented in the paper. Two experiments under different conditions are accomplished and experiment results are compared. One experiment is completed with the distance constraint and another without. The experiment results are compared by two parameters: tightness and residuals. The measured object is an inflatable antenna with a 3.5-m diameter.

Automated Image Processing for on-Line Photogrammetry

2011 ◽  
Vol 130-134 ◽  
pp. 3577-3580
Author(s):  
Jun Wang ◽  
Ming Li Dong
Keyword(s):  
Image Processing ◽  
High Accuracy ◽  
Process Time ◽  
Pixel Size ◽  
Dynamic Adjustment ◽  
Close Range Photogrammetry ◽  
Close Range ◽  
On Line ◽  
Line Photogrammetry ◽  
Automated Image Processing

In order to monitor the deformation of the surface or dynamic adjustment and measurement, the real-time and on-line close range photogrammetry system is needed. Before camera calibration and 3D reconstruction, the targets in the images must be recognized and located automatically with high accuracy and speed firstly. This paper describes the automated image processing for the on-line photogrammetry system. Experimental results show that compared with the other measurement system, the accuracy of subpixel target centroid can reach to about 2% of the pixel size, while the process time of an image with 3008×2000 pixels is about 0.1S.

scholarly journals Underexposed Vision-Based Sensors’ Image Enhancement for Feature Identification in Close-Range Photogrammetry and Structural Health Monitoring

2021 ◽  
Vol 11 (23) ◽  
pp. 11086
Author(s):  
Luna Ngeljaratan ◽  
Mohamed A. Moustafa
Keyword(s):  
Structural Health Monitoring ◽  
Image Enhancement ◽  
Health Monitoring ◽  
Bundle Adjustment ◽  
Practical Implementation ◽  
Identification Algorithm ◽  
Feature Identification ◽  
Structural Health ◽  
Close Range Photogrammetry ◽  
Close Range

This paper describes an alternative structural health monitoring (SHM) framework for low-light settings or dark environments using underexposed images from vision-based sensors based on the practical implementation of image enhancement algorithms. The proposed framework was validated by two experimental works monitored by two vision systems under ambient lights without assistance from additional lightings. The first experiment monitored six artificial templates attached to a sliding bar that was displaced by a standard one-inch steel block. The effect of image enhancement in the feature identification and bundle adjustment integrated into the close-range photogrammetry were evaluated. The second validation was from a seismic shake table test of a full-scale three-story building tested at E-Defense in Japan. Overall, this study demonstrated the efficiency and robustness of the proposed image enhancement framework in (i) modifying the original image characteristics so the feature identification algorithm is capable of accurately detecting, locating and registering the existing features on the object; (ii) integrating the identified features into the automatic bundle adjustment in the close-range photogrammetry process; and (iii) assessing the measurement of identified features in static and dynamic SHM, and in structural system identification, with high accuracy.

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