Hossam El-Din Fawzy Lecturer, Civil Engineering Department, Faculty of Engineering, Kafr El-Sheikh University, Kafr El-Sheikh, EGYPT

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1 International Journal of Civil Engineering and Technology (IJCIET) Volume 6, Issue 10, Oct 015, pp , Article ID: IJCIET_06_10_013 Available online at ISSN Print: and ISSN Online: IAEME Publication THE EFFICIENT OF USING THE CLOSE RANGE PHOTOGRAMMETRY TECHNIQUE INSTEAD OF A PRECISE TERRESTRIAL SURVEYING TECHNIQUE FOR DEFORMATION MONITORING IN UNSTABLE STRUCTURE BUILDINGS Hossam El-Din Fawzy Lecturer, Civil Engineering Department, Faculty of Engineering, Kafr El-Sheikh University, Kafr El-Sheikh, EGYPT ABSTRACT Time, cost and accuracy required are the important factors that decide on the deformation monitoring in unstable structure buildings. Several methodologies are currently following when a precise determination of displacements is required. In this paper, close range Photogrammetry is an alternative method for deformation monitoring. The main objective of this paper has investigated the use of close range Photogrammetry to calculate the deformation monitoring instead of Precise terrestrial surveying methods. Precise terrestrial surveying methods have been insufficient for the Deformation monitoring in a short time and low cost or in a risk area. This paper gives also the sequence of the field operations and computational steps for this task. Key words: Close Range Photogrammetry, Precise Terrestrial Surveying, Accuracy, Deformation Monitoring. Cite this Article: Hossam El-Din Fawzy. The Efficient of Using The Close Range Photogrammetry Technique Instead of A Precise Terrestrial Surveying Technique For Deformation Monitoring In Unstable Structure Buildings. International Journal of Civil Engineering and Technology, 6(10), 015, pp INTRODUCTION In the 014 plans have been initiated for removing the inclined building in the city of Kafr El-Sheikh, Egypt. The dimension of inclined building is about 16m long, 14m wide and 41m height as shown in figure 1. In the neighborhood of the construction site a number of buildings exist, mainly built between 1985 and 01. Due to possible editor@iaeme.com

2 Hossam El-Din Fawzy ground movements subsequent movements of the buildings can be expected that could lead to significant damages. Figure 1 The Inclined Building in The City of Kafr El-Sheikh, Egypt. In order to avoid claims for damages without good reasons, the project leader has placed orders for extensive evidence control measurements. These should document the existing damages on buildings before any remove of inclined building work has been started. This includes all visible damages on interior and exterior parts of the buildings. Each damage is then measured by special gauges or tools, and documented by photographs. This work has been carried out by legally authorized experts. In this work a precise three-dimensional monitoring of the building was required for studying the structural stability before the any remove of inclined building work has been started. Several methodologies are currently following when a precise determination of displacements is required. In the present case the environment was highly restrictive. To start with, the work had to be conducted in a closed building where some of the monitoring points were not intervisible: some points were on the outside walls while others were on the inside walls. Besides, an extremely high precision of about 1 mm was demanded for the determination of the possible displacements. Considering these severe limitations, a review of the adequacy of specific current technologies was conducted as the initial task. Precise terrestrial surveying techniques are the classic procedures for the determination of displacements. They are based on the measurement of geometric quantities: horizontal or zenith angles by means of a theodolite within an accuracy that can reach 1", distances by means of an electronic distance meter (EDM) within a usual accuracy of 3 to 5 mm/km, and differences of height by geometric levelling within an accuracy of some tenths of a millimeter for a single measure. Precise terrestrial surveying techniques have been used for very precise coordinate determinations in particular for slope deformation monitoring and also for structural studies. These techniques are able to connect non-intervisible monitoring points.[11] Close range photogrammetry is one of the main techniques currently used for the restoration of buildings. Its main capability is to attach the visual information to the geometry under study with a potential accuracy of submillimeter. A benefit of close range photogrammetry is that a photo record is kept of all the data that are measured, which allow the measurements to be checked in the future. [11] Global Positioning System techniques are widely used in surveying and geodesy. They track the signals transmitted by the NAVSTAR satellite constellation and editor@iaeme.com

3 The Efficient of Using The Close Range Photogrammetry Technique Instead of A Precise Terrestrial Surveying Technique For Deformation Monitoring In Unstable Structure Buildings provide a relative accuracy of 5 mm ± 1 mm/km. Although Global Positioning System technique has been used for restoration works, it was unsuitable for a closed building since the satellite signals cannot be tracked from the inside. [11] Laser scanning-based surveying techniques are also able to provide a centimeter level accuracy and therefore are becoming increasingly interesting for restoration works. However, the submillimetre accuracy required is beyond its capabilities. [11] Finally, it was decided to use close range photogrammetry technique for a precise three-dimensional monitoring of the building and check of result by precise terrestrial surveying technique. This paper gives also the sequence of the field operations and computational steps for this task by two methods (close range photogrammetry and precise terrestrial surveying techniques).. CLOSE RANGE PHOTOGRAMMETRY TECHNIQUE Close range Photogrammetry is a three-dimensional measurement technique which uses central projection imaging as its fundamental mathematical model often associated with a simple device called the pinhole camera. Three elements are sufficient to fully describe the perspective of a pinhole camera: the focal distance and the two coordinates of the point where the optical axis intersect the image plane (Interior Orientation), referring to a specific frame on the image plane. The camera calibration procedure retrieves perspective elements, known as Interior Orientation (IO) parameters, together with the radial and decentring lens distortion parameters, known as Additional Parameters (AP). Close range Photogrammetry is able to get three dimensional (3D) data of an object from images in a way that is very similar to theodolite survey techniques, since it is based on the intersection between two or more optical rays (redundancy) called collinearity straight lines in photogrammetric terminology. Within the perspective model, the object point, perspective center and image point lie on the same collinearity straight line. The image acquisition stage consists in taking photographs of the object from different view positions, ensuring good intersection between collinearity straight lines. The photogrammetric process is strictly linked to marking some homologous object points on the images to determine both camera positions and orientations, called Exterior Orientation (EO), as well as 3D point coordinates. The recognition of the same object point on two or more images (image correspondences) requires the object surface to have enough texture information (such as natural points and/or edges, etc.). If no features are visible on the images, then artificial targets must be positioned and/or synthetic patterns must be projected or painted on the object surface. For some applications, i.e. For high automation and accuracy purposes, circular coded targets should be positioned on the object to automatically recognize image correspondences.[4] While IO establishes the geometric characteristics of a bundle of rays, the EO establishes its position and orientation with respect to the object space coordinates system. Each bundle requires six independent parameters: three for position and three for orientation. These parameters can be calculated either through the knowledge of at least three object point coordinates (single image orienting or resection method) or by marking the same object points (at least five) on two or more images (image pairs orienting or relative orientation method). Once the approximate values for exterior orientation parameters have been computed or estimated, a least square evaluation by means of a bundle adjustment process (multi image orienting) is performed in order to improve accuracy. [4] editor@iaeme.com

4 Hossam El-Din Fawzy Once the exterior orientation parameters have been computed, different kinds of 3D measurements are possible (points, segments and/or straight lines, planar geometric shapes, solids, etc.). Generally, a rough approximation of accuracy achievable with photogrammetric measurements can be derived directly from uncertainty in marking the imaged geometric primitives. Figure illustrates the model presented for reconstruction of a light rays uses two sets of coordinates, where (x, y) represents the position of an observed point projection in a photograph. Figure Relation between object and photograph point Reconstruction of an optical straight-line consists in establishing a functional relation between the object and image coordinates. This model is sufficient for considering a measurement in the plane with two unknown values of the object coordinates X and Y, (Z = 0), and they can be calculated using two equations of image coordinates (x, y). [4] Abdel Aziz and Karara proposed a simple method for close range photogrammetric data reduction with non- metric cameras; it establishes the Direct Linear Transformation (DLT) between the two-dimensional coordinates, and the corresponding object - space coordinates. [1] The Direct Linear Transformation (DLT) between a point (X, Y, Z) in object space and its corresponding image space coordinates (x, y) can be established by the linear fractional equations [1]: L1 X LY L3Z L4 f xx L X L Y L Z L5 X L6Y L7Z L8 g yy L9 X L10Y L11Z 1 Where: L 1, L, L 3 L 11 are the transformation parameters X, Y and Z are the object space coordinates 11 (1) editor@iaeme.com

5 The Efficient of Using The Close Range Photogrammetry Technique Instead of A Precise Terrestrial Surveying Technique For Deformation Monitoring In Unstable Structure Buildings x y y y ) () 4 6 xx ( k1 r k r k3 r ) p1 ( r x ) p 4 6 y ( k1 r k r k3 r ) p1 x y p ( r Where: x - = x x o y - = y y o r = (x xo) + (y yo) x, y are image coordinates p 1 and p are two asymmetric parameters for decentring distortion k 1, k and k 3 are three symmetric parameters for radial distortion r is the radial distance from the principal point.[],[3] A 3D measurement includes three unknown values of object coordinates X, Y,Z. Two equations of image coordinates are not enough for calculation of three coordinates. Additional equations of image coordinates are necessary to solve the problem. The object point has to be recorded from another position, which gives two additional equations. The system of the equations is predefined. The optical measurement techniques for calculation of a point position in space are based on stereoscopic effect. A 3D position of a point is determined by triangulation, as shown in Figure 3. Figure 3 Triangulation principle The position of a point is determined from an intersection of straight lines. The lines are defined by a point P and its projection points P 1 \ and P \ on photographs. It is necessary to set up additional equations in order to record the point from another camera position and make a redefinition of the system, i.e. a larger number of equations than unknowns possible. The system of nonlinear equations redefined in this way is solved iteratively by an error minimization method, and the outputs of this analysis are 3D coordinates of measuring points and other parameters of the mathematical model.[4] 3. PRECISE TERRESTRIAL SURVEYING TECHNIQUE In precise terrestrial surveying technique, the deformation monitoring was divided into two parts: planimetry and altimetry. The instrumentation, measurement methodology and monitoring marks should then be established consequently. [11] For the altimetric study, five benchmarks were located far from the inclined building and the neighborhood building in order to be free from possible deformations. They define the height origin after having been interconnected by editor@iaeme.com

6 Hossam El-Din Fawzy digital level measurements so as to represent a stable reference frame even in case of the disappearance or displacement of a small number of them. Other height monitoring marks were located in the outside and inside walls of the inclined building and the neighboring building. It was impossible to measure the benchmarks located over the walls by geometric levelling. The benchmark was very high in these monitoring points, making it impossible to set up the levelling staffs. Therefore trigonometric levelling was used jointly with geometric levelling. The planimetric monitoring was conducted by means of angle measurements and at least one distance (to fix the scale of the network) only in the space over the vaults for the same monitoring marks as used for the altimetry. The angle measurements with the theodolite were obtained within an accuracy of about one second of arc which for the distances involved represents of mm. The widespread total stations in use today rarely measure to better than 1 mm even when taking precise measurements of temperature, pressure and humidity. 4. EXPERIMENTAL STUDY In 014, as part of remove the inclined building in the city of Kafr El-Sheikh, Egypt, many observations were carried using close range photogrammetry and precise terrestrial surveying techniques to determine the displacements. In close range photogrammetry techniques, A professional software for 3D modeling and measurement (PhotoModeler software) was used to collect the image data from the test specimens. Before the image acquisition, 1 photographs of the calibration grid, which provided by the software supposed to be taken from twelve different positions and angles, and then be imported to the software to finish the calibration process.[10] A normal 14. mega pixels Digital Camera Nikon D 3100 (Figure 4) was used in this application for the image acquisition [7]. When processing the photographs, some selected points need to be marked and then be cross-reference in photographs taken from various angles. Compared to the conventional photogrammetric procedures, PhotoModeler allows even greater reduction of time and costs for the production of models, since it does not require positioning and measuring of targets and stereoscopy to produce suitable photographic documents.[5] Figure 4 The Nikon D 3100 digital camera It has been shown that the method of measuring facades with the PhotoModeler software is efficient when having common points easily identifiable at least on 3 or 4 photographs, and this was sometimes impossible depending on the kind of object being measured and the characteristics of its surface and materials. The present experience has shown that the use of clearly identified and well-distributed high resolution targets over the facades was recommended.[10] 15 editor@iaeme.com

7 The Efficient of Using The Close Range Photogrammetry Technique Instead of A Precise Terrestrial Surveying Technique For Deformation Monitoring In Unstable Structure Buildings Therefore, when for taking photographs after the calibration process, each selected point must be visible at least in two photographs that have been taken at an angle larger than 45 degrees to the object. And it is well acknowledged that more photographs with the same points make more accurate results. Ideal lighting conditions had been arranged for a uniform light scene during the image acquisition process, thus for not producing hard shadows which make points difficult to mark and reference.[4] All photographs were well focused. Once a good number of points have been marked, they need to be cross-referenced. The points in the proposed order are supposed to be selected in the second photograph, following the prompts in the first photograph. After the referencing of all points needed, the model can be processed into a 3D model, where the surfaces can be added between points or lines. When the surfaces exist in the model, the textures could be mapped onto the surfaces to make the model looks exactly the same as the reality. [4] The final photogrammetric model is able to be exported into many different formatted files and to be used in various engineering programs. For instance, it can be exported as a.dxf file which can be used in AutoCAD, or a.igs file which will be used in ANSYS, in which the processing and post processing would be performed.[10] In precise terrestrial surveying techniques, the five remote altimetric origin benchmarks were connected to the ten height monitoring marks on the outer walls of the building under monitoring by means of precise geometric levelling, and then 4 marks along the inner walls of the building under monitoring. Typical precisions were estimated to be some tenths of mm. The geometric levelling was conducted with a Sokkia power level SDL 30 and provides a reading by estimation to decimals when measuring mode is tracking. The Sokkia power level SDL 30 used is shown in Figure 5.[9] The trigonometric levelling was conducted with a Sokkia Reflector less Total Station (SET330RK) as shown in Figure 6. The observations with the Sokkia Reflector less Total Station provided all automatic determinations with a submillimetre accurate.[8] Figure 5 The Sokkia power level SDL30 Figure 6 The Sokkia Reflector less Total Station (SET330RK) Three independent distances between the benchmarks were measured by Sokkia Reflector less Total Station (SET330RK). The observations with the Sokkia Reflector less Total Station provided all altimetric determinations with submillimetre accuracy editor@iaeme.com

8 Hossam El-Din Fawzy All of the 136 visible horizontal directions with the theodolite mode were measuring the angles in two faces), also all of the 136 visible zenith angles with the theodolite mode (in two faces). 5. ASSESSMENT OF ACCURACY There are two different methods can be used to evaluate accuracy: one can evaluate accurately by using check measurements and determining from these check measurements the value of appropriate accuracy criteria; and one can use accuracy predictors. In this study, check measurements will be used to evaluate the accuracy. In this study, we consider checking points in the studied object that is points whose true coordinates X it, Y it and Z it are known by using a precise terrestrial surveying technique before any remove of inclined building work. Then X ic, Y ic and Z ic are the coordinates of the check points after removing the four floors of the inclined building by two techniques (close range Photogrammetry technique and precise terrestrial surveying technique), an estimation of the MRXYZ spatial residual is[6]: MRXYZ ( Yic Xit) ( Yic Xit ) ( Zic Zit Analogous quantities can be estimated for three axes: ) (3) The X- direction: MRX ( Y ic Xit) The Y-direction: MRY ( Y ic Xit ) The Z-direction: MRZ ( Z ic Zit) 6. THE RESULTS The deformation result of the 3-D point positioning of the monitoring mark with both techniques (close range Photogrammetry technique and precise terrestrial surveying technique) after removing the four floors of the inclined building as shown in Figure 7 and summarized in table 1. Figure 7 the inclined building after removing the four floors editor@iaeme.com

9 The Efficient of Using The Close Range Photogrammetry Technique Instead of A Precise Terrestrial Surveying Technique For Deformation Monitoring In Unstable Structure Buildings Table 1 Statistics for the deformation result of 3-D point positioning in mm of the monitoring mark with both techniques (close range Photogrammetry technique and precise terrestrial surveying technique) after removing the four floors of inclined building Close range Photogrammetry Precise terrestrial surveying MRX MRY MRZ MRXYZ MRX MRY MRZ MRXYZ Using insight into Table 1 some interesting points are noted: There have not been significant displacements except for the points (13, 14, 15 and 16 at the neighboring building in the north direction of inclined building) in the which have subsided a detectable amount of 4 mm In the X, Y and Z direction, the best accuracy has been obtained, when the precise terrestrial surveying technique is used According to the obtained results, The average accuracy of the photogrammetric measurement technique amount 1 mm but the average measuring accuracy of the editor@iaeme.com

10 Hossam El-Din Fawzy terrestrial surveying technique amounts to 0.1mm for precise leveling and also 0.1mm for 3-D point determinations using the theodolite system. 7. CONCLUSIONS The close range Photogrammetry technique and precise terrestrial surveying technique have been used in a precise three-dimensional monitoring of the building and the obtained accuracy is discussed and presented. From all of the above discussions, the following conclusions can be drawn: The close range Photogrammetry technique is easier to implement and faster than the precise terrestrial surveying technique. The close range Photogrammetry technique has a great reduction of time and cost than the precise terrestrial surveying technique. The accuracy of the precise terrestrial surveying technique can be given good results in comparison with The close range Photogrammetry technique. Based on the experimental results, it can be seen that the numeric results show the stability for most of the benchmarks. The initial results, however, also show a possible instability of points 13, 14, 15 and 16 in the neighboring building in the north direction of inclined building. Future campaigns will have to confirm or disprove these. Seasonal displacements were observed with a high level of confidence for points (13, 14, 15 and 16) at locations where some structure weakness is suspected. Additional measurement campaigns are suggested for the next years in order to obtain a more reliable monitoring modelisation. REFERENCES [1] Abdel-Aziz, Y. I. and Karara, H. M., Direct Linear Transformation of Comparator Coordinates into Object Space Coordinates in Close Range Photogrammetry Proceedings of the ASP/UI Symposium on Close-Range Photogrammetry, Urbana, Illinois, pp [] Abdel-Aziz, Y. I., Lens Distortion and Close Range Civil Engineering studies, Cairo University, Cairo, Egypt, Proceedings of the Photogrammetric engineering & remote sensing, Urbana, Illinois, pp [3] Abdel-Aziz, Y. I., Asymmetrical Lens Distortion Civil Engineering studies, Cairo University, Cairo, Egypt, Proceedings of the Photogrammetric engineering & remote sensing (pp ). [4] Chen, B.Q.; Garbatov, Y.; Guedes Soares, C., 009. "Automatic Approach for Measuring Deformations in Complex Structures Using Photogrammetry Technique" Centre for Marine Technology and Engineering (CENTEC), Instituto Superior Técnico, Technical University of Lisbon, Av. Rovisco Pais, Lisboa, Portugal. [5] Hossam El-Din Fawzy, 015. The Accuracy of Determining the Volumes Using Close Range Photogrammetry IOSR Journal of Mechanical and Civil Engineering (IOSR-JMCE) e-issn: ,p-ISSN: X, Volume 1, Issue Ver. VII (Mar - Apr. 015), PP [6] Hottier, 1976 " Accuracy of close -Range Analytical Restitutions: Practical Experiments and Prediction" Photogrammetric Engineering and Remote sensing, Vol.4, No.3, pp [7] search on technical specifications of the Nikon D 3100 camera editor@iaeme.com

11 The Efficient of Using The Close Range Photogrammetry Technique Instead of A Precise Terrestrial Surveying Technique For Deformation Monitoring In Unstable Structure Buildings [8] Rk3-Set330rk-Rk3-Set530rk-Rk3-Set630rk-En, 015 [9] [10] PhotoModeler, 015. Eos Systems Inc., [11] S. Baselga, P. Garrigues, J. L. Berné, A. B. Anquela and A. Martín, 011. "Deformation Monitoring in Historic Buildings: A Case Study" Survey Review, 43, 33 pp , October 011. [1] Hossam El-Din Fawzy. The Accuracy of Mobile Phone Camera Instead of High Resolution Camera in Digital Close Range Photogrammetry. International Journal of Civil Engineering and Technology, 6(1), 015, pp [13] Hossam El-Din Fawzy. Comparison between the Genetic Algorithms Optimization and Particle Swarm Optimization for Design the Close Range Photogrammetry Network. International Journal of Civil Engineering and Technology, 6(6), 015, pp [14] Mr. Vineeth Raphael and Mrs. Jenifer Priyanka. Role of Building Information Modelling (BIM) In Quantity Surveying Practice. International Journal of Civil Engineering and Technology, 5(1), 014, pp [15] Rasheed Saleem Abed. Experience on Using Total Station Surveying For Mapping and Contouring. International Journal of Civil Engineering and Technology, 4(3), 013, pp editor@iaeme.com