scholarly journals A COMPARISON STUDY BETWEEN COLLINEARITY CONDITION, COPLANARITY CONDITION, AND DIRECT LINEAR TRANSFORMATION (DLT) METHOD FOR CAMERA EXTERIOR ORIENTATION PARAMETERS DETERMINATION

2015 ◽  
Vol 41 (2) ◽  
pp. 66-73 ◽  
Author(s):  
Khalid L. A. El-Ashmawy
Keyword(s):  
Linear Transformation ◽  
Mathematical Formulation ◽  
Comparison Study ◽  
Exterior Orientation ◽  
Comparison Of The Results ◽  
Orientation Parameters ◽  
Better Than

The present work emphasizes on using collinearity condition, coplanarity condition and DLT method for determining the camera exterior orientation parameters. The derivation of the mathematical formulation based on each suggested methods is explained. The comparison of the results of the methods was performed based on accuracy aspects using mathematical and actual photogrammetric data. The used data shows that the suggested methods are suitable for camera exterior orientation parameters determination for a block of photographs of any size. The results of this investigation prove that the accuracy of using coplanarity equations is slightly better than using collinearity equations or DLT method. Although the results of the DLT method are less accurate than those of using collinearity or coplanarity equation, DLT method is essential when the necessary information for the collinearity or coplanarity model is not available. This paper shows the necessity for the mathematical photogrammetric data for testing the photogrammetric studies.

scholarly journals ESTIMATING EXTERIOR ORIENTATION PARAMETERS OF HYPERSPECTRAL BANDS BASED ON POLYNOMIAL MODELS

2017 ◽  
Vol XLII-3/W3 ◽  
pp. 19-25 ◽  
Author(s):  
A. Berveglieri ◽  
A. M. G. Tommaselli ◽  
E. Honkavaara
Keyword(s):  
Real Data ◽  
Bundle Adjustment ◽  
Time Dependent ◽  
Camera Model ◽  
Exterior Orientation ◽  
Spectral Bands ◽  
Acquisition Mode ◽  
Polynomial Models ◽  
Orientation Parameters ◽  
Sequential Acquisition

Hyperspectral camera operating in sequential acquisition mode produces spectral bands that are not recorded at the same instant, thus having different exterior orientation parameters (EOPs) for each band. The study presents experiments on bundle adjustment with time-dependent polynomial models for band orientation of hyperspectral cubes sequentially collected. The technique was applied to a Rikola camera model. The purpose was to investigate the behaviour of the estimated polynomial parameters and the feasibility of using a minimum of bands to estimate EOPs. Simulated and real data were produced for the analysis of parameters and accuracy in ground points. The tests considered conventional bundle adjustment and the polynomial models. The results showed that both techniques were comparable, indicating that the time-dependent polynomial model can be used to estimate the EOPs of all spectral bands, without requiring a bundle adjustment of each band. The accuracy of the block adjustment was analysed based on the discrepancy obtained from checkpoints. The root mean square error (RMSE) indicated an accuracy of 1 GSD in planimetry and 1.5 GSD in altimetry, when using a minimum of four bands per cube.

scholarly journals A General Point-Based Method for Self-Calibration of Terrestrial Laser Scanners Considering Stochastic Information

2020 ◽  
Vol 12 (18) ◽  
pp. 2923
Author(s):  
Tengfei Zhou ◽  
Xiaojun Cheng ◽  
Peng Lin ◽  
Zhenlun Wu ◽  
Ensheng Liu
Keyword(s):  
Point Cloud ◽  
A Priori ◽  
Real Data ◽  
Point Clouds ◽  
Estimation Algorithm ◽  
General Point ◽  
Exterior Orientation ◽  
Self Calibration ◽  
Laser Scanners ◽  
Orientation Parameters

Due to the existence of environmental or human factors, and because of the instrument itself, there are many uncertainties in point clouds, which directly affect the data quality and the accuracy of subsequent processing, such as point cloud segmentation, 3D modeling, etc. In this paper, to address this problem, stochastic information of point cloud coordinates is taken into account, and on the basis of the scanner observation principle within the Gauss–Helmert model, a novel general point-based self-calibration method is developed for terrestrial laser scanners, incorporating both five additional parameters and six exterior orientation parameters. For cases where the instrument accuracy is different from the nominal ones, the variance component estimation algorithm is implemented for reweighting the outliers after the residual errors of observations obtained. Considering that the proposed method essentially is a nonlinear model, the Gauss–Newton iteration method is applied to derive the solutions of additional parameters and exterior orientation parameters. We conducted experiments using simulated and real data and compared them with those two existing methods. The experimental results showed that the proposed method could improve the point accuracy from 10−4 to 10−8 (a priori known) and 10−7 (a priori unknown), and reduced the correlation among the parameters (approximately 60% of volume). However, it is undeniable that some correlations increased instead, which is the limitation of the general method.

scholarly journals Comparison of Periodic Flow Fields in a Radial Pump among CFD, PIV, and LDV Results

2009 ◽  
Vol 2009 ◽  
pp. 1-10 ◽  
Author(s):  
Jianjun Feng ◽  
F.-K. Benra ◽  
H. J. Dohmen
Keyword(s):  
Unsteady Flow ◽  
Laser Doppler Velocimetry ◽  
Particle Image ◽  
Velocity Fields ◽  
Image Velocimetry ◽  
Rotating Impeller ◽  
Low Specific Speed ◽  
Radial Pump ◽  
Comparison Of The Results ◽  
Better Than

The interaction between the impeller and the diffuser is considered to have a strong influence on the unsteady flow in radial pumps. In this paper, the unsteady flow in a low specific speed radial diffuser pump has been simulated by the CFD code CFX-10. Both Particle Image Velocimetry (PIV) and Laser Doppler Velocimetry (LDV) measurements have been conducted to validate the CFD results. Both the phase-averaged velocity fields and the turbulence fields obtained from different methods are presented and compared, in order to enhance the understanding of the unsteady flow caused by the relative motion between the rotating impeller and the stationary diffuser. The comparison of the results shows that PIV and LDV give nearly the same phase-averaged velocity fields, but LDV predicts the turbulence much clearer and better than PIV. CFD underestimates the turbulence level in the whole region compared with PIV and LDV but gives the same trend.

A NEW MATHEMATICAL MODEL FOR FINITE-DIFFERENCE SOLUTION OF THREE-DIMENSIONAL MIXED-BOUNDARY-VALUE ELASTIC PROBLEMS

2005 ◽  
Vol 02 (01) ◽  
pp. 99-126 ◽  
Author(s):  
M. ZUBAER HOSSAIN ◽  
S. REAZ AHMED ◽  
M. WAHHAJ UDDIN
Keyword(s):  
Finite Difference ◽  
Potential Function ◽  
Solid Mechanics ◽  
Present Model ◽  
Mixed Boundary ◽  
Boundary Value ◽  
Mathematical Formulation ◽  
Three Dimensional ◽  
Computational Time ◽  
Comparison Of The Results

This paper describes a new mathematical formulation, specifically suitable for finite-difference analysis of stresses and displacements of three-dimensional mixed-boundary-value elastic problems. Earlier, mathematical models of elasticity were very deficient in handling three-dimensional practical stress problems. In the present model, a new scheme of reduction of unknowns is used to formulate the three-dimensional problem in terms of a single potential function, defined in terms of the three displacement components. Compared to the conventional models, the present model provides numerical solution of higher accuracy in a shorter period of computational time. The application of the potential function formulation is demonstrated here through a number of classical problems of solid mechanics, and the results are compared with the available solutions in the literature. The comparison of the results establishes the rationality of the present approach.

Study on the Development of Resource-Saving High Performance Slurry - Polishing/CMP for Glass Substrates in a Radical Polishing Environment, Using Manganese Oxide Slurry as an Alternative for Ceria Slurry

2010 ◽  
Vol 64 ◽  
pp. 65-70 ◽  
Author(s):  
Toshiro K. Doi ◽  
Tsutomu Yamazaki ◽  
Syuhei Kurokawa ◽  
Yoji Umezaki ◽  
Osamu Ohnishi ◽  
...  
Keyword(s):  
Manganese Oxide ◽  
Chemical Mechanical Polishing ◽  
High Performance ◽  
Removal Rate ◽  
Comparison Study ◽  
Resource Saving ◽  
Glass Substrates ◽  
Closed Type ◽  
Quality Surface ◽  
Better Than

While investigating polishing mechanism of glass substrates with ceria abrasives (CeO2), we found its oxidizing properties worked effectively for the polishing. This finding has inspired us to speculate about the possibility of the manganese oxide abrasives as an alternative for ceria as they also have oxidizing properties. Therefore, focusing on the valence of the manganese, we have experimentally manufactured MnO, MnO2, Mn2O3 and Mn3O4 abrasives, and conducted a comparison study of the characteristics obtained with ceria slurry and manganese oxide slurries. As a result, the surface roughness of below Ra 0.8nm obtained with Mn2O3 slurry was found better than that with the conventional ceria slurry, on top of which, its removal rate was as good as or equal to that of ceria. Using a novel, closed type CMP (Chemical Mechanical Polishing) machine, we conducted another glass polishing experiment with ceria and manganese oxide slurries. The inside of the CMP machine was filled with high-pressure gases such as oxygen, air and nitrogen and kept at 500kPa to make the polishing environment radical. Through this experiment, we found an effective polishing method for high-quality surface. The removal rates were several times better than that of the conventional polishing performed in an open CMP machine.

scholarly journals APPLICATIONS OF PANORAMIC IMAGES: FROM 720° PANORAMA TO INTERIOR 3D MODELS OF AUGMENTED REALITY

2015 ◽  
Vol XL-4/W5 ◽  
pp. 189-192 ◽  
Author(s):  
I.-C. Lee ◽  
F. Tsai
Keyword(s):  
Augmented Reality ◽  
Focal Length ◽  
Three Dimensional ◽  
Point Clouds ◽  
3D Models ◽  
Exterior Orientation ◽  
3D Point Clouds ◽  
Panoramic Images ◽  
Main Station ◽  
Orientation Parameters

A series of panoramic images are usually used to generate a 720° panorama image. Although panoramic images are typically used for establishing tour guiding systems, in this research, we demonstrate the potential of using panoramic images acquired from multiple sites to create not only 720° panorama, but also three-dimensional (3D) point clouds and 3D indoor models. Since 3D modeling is one of the goals of this research, the location of the panoramic sites needed to be carefully planned in order to maintain a robust result for close-range photogrammetry. After the images are acquired, panoramic images are processed into 720° panoramas, and these panoramas which can be used directly as panorama guiding systems or other applications. <br><br> In addition to these straightforward applications, interior orientation parameters can also be estimated while generating 720° panorama. These parameters are focal length, principle point, and lens radial distortion. The panoramic images can then be processed with closerange photogrammetry procedures to extract the exterior orientation parameters and generate 3D point clouds. In this research, VisaulSFM, a structure from motion software is used to estimate the exterior orientation, and CMVS toolkit is used to generate 3D point clouds. Next, the 3D point clouds are used as references to create building interior models. In this research, Trimble Sketchup was used to build the model, and the 3D point cloud was added to the determining of locations of building objects using plane finding procedure. In the texturing process, the panorama images are used as the data source for creating model textures. This 3D indoor model was used as an Augmented Reality model replacing a guide map or a floor plan commonly used in an on-line touring guide system. <br><br> The 3D indoor model generating procedure has been utilized in two research projects: a cultural heritage site at Kinmen, and Taipei Main Station pedestrian zone guidance and navigation system. The results presented in this paper demonstrate the potential of using panoramic images to generate 3D point clouds and 3D models. However, it is currently a manual and labor-intensive process. A research is being carried out to Increase the degree of automation of these procedures.

scholarly journals ANALYSIS OF ORIENTATION ACCURACY OF AN UAV IMAGE ACCORDING TO CAMERA CALIBRATION

2019 ◽  
Vol XLII-2/W13 ◽  
pp. 437-442 ◽  
Author(s):  
P. C. Lim ◽  
J. Seo ◽  
J. Son ◽  
T. Kim
Keyword(s):  
Camera Calibration ◽  
Exterior Orientation ◽  
Time Saving ◽  
Commercial Grade ◽  
Sensing Platforms ◽  
Small Uav ◽  
Uav Image ◽  
Orientation Parameters ◽  
Easy Operation

<p><strong>Abstract.</strong> Utilization of an UAV is increasing because of its easy operation and time saving advantages. Compared with other remote sensing platforms, the biggest difference of a small UAV is the unstable flight attitude due to platform stability. UAVs are equipped with a commercial grade camera, unlike expensive cameras mounted on manned aircraft or satellite platforms. The quality of the map is determined by the characteristics of an UAV and camera performance. In this study, the accuracy of orientation parameters according to UAV camera calibration options was analysed. The camera calibration options were no calibration, self-calibration and calibration by a public calibration toolkit with manual corner measurement. We used four different type of UAVs and three type of SWs. Interior and exterior orientation parameters according to the camera calibration options were obtained from each software. The result of processing by each camera calibration option was different from each other. This may indicate that the UAV camera calibration was not performed accurately and still needed further improvement.</p>

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