**Application of a Photogrammetric System for Monitoring Civil Engineering Structures**

Junggeun Han1,\*, Kikwon Hong2 and Sanghun Kim3 *1School of Civil and Environmental Engineering, Urban Design and Study,Chung-Ang University, Seoul 2Green Technology Institute, Chung-Ang University, Seoul 3ReStl Designers, Inc., Maryland 1,2South Korea 3USA* 

#### **1. Introduction**

72 Special Applications of Photogrammetry

Krakau, C.E.T. (1970). A device for the automatic. Continuous recording of stereoscopic

Kraus, K., (1993). *Photogrammetry Vol. 1. Fundamentals and standard processes* (4th edition),

Lehmann, G. (1955). Report on the work hitherto archieved by Commission C of the O.E.E.P.E. *Photogrammetria*, , Vol. 12 (1955), pp 156-163, ISSN 0031-8663 . O'Connor, D. (1967). Some factors affecting the precision of coordinate measurements on

Schiewe, J. (1995). Cartographical Potential of MOMS-02/D2 Image Data. In:

Spreckels, V., Syrek, L., Schlienkamp, A. (2010). DGPF Project: Evaluation of Digital

Stark, E. (1975). The effect on angular field on horizontal and vertical accuracy in

Stickler, C.A. (1959). Interpretation of the results of the O.E.E.P.E. commission C.

Stoch, L. (1961). Note on C. A. Stickler's Paper. *Photogrammetria*, Vol. 18 (1961), pp 34, ISSN

Trinder, J.C. (1986). Potentials of monocular and stereoscopic observations on aerial

Wolf, P.R. & Ghilani, C.D. (1997). *Adjustment computations: statistics and least squares in surveying and GIS*. Ed. John Wiley and Sons,ISBN 0471168335, New York, EEUU. Zorn, H. C. (1965). An instrument for testing stereoscopic acuity. *Photogrammetria*, Vol. 20,

*Photogrammetria*, , Vol. 16 (1959), pp 8-12, ISSN 0031-8663.

Issue 6 (December 1965), pp 229-238, ISSN 0031-8663 .

Dümmler, ISBN 3427786846, Bonn, Germany.

0031-8663.

0031-8663.

8364.

(Germany), 1975.

0031-8663.

8663.

visual acuity. *Photogrammetria*, , Vol. 25, Issue 4 (February 1970), pp 115-123, ISSN

photographic plates. *Photogrammetria*, Vol. 22, Issue 3 (March 1967), pp 77-97, ISSN

Photogrammetric Week´95. Heidelberd: Ed. Fritsch/Hobbie, Wichmann. pp 99-105.

Photogrammetric Camera Systems – Stereoplotting. *Photogrammetrie - Fernerkundung - Geoinformation*, Vol. 2010, No. 2 (May 2010), pp. 117-130, ISSN 1432-

photogrammetric plotting. *Procedings of Photogrammetric Week*, pp 129-145, Stuttgart

photographs. *Photogrammetria*, Vol. 41, Issue 1 (October 1986), pp 17-27, ISSN 0031-

Several traditional measuring apparatus are used to check the stability of civil engineering structures and maintenance of them. The measured results are applied for the deformation and stability analysis of civil engineering structures. Currently, precision and micro measuring instruments are used for stability evaluations of civil engineering structures. Furthermore, the measuring apparatus have been changed from manual systems to automatic systems. For example, total station, one of the traditional and manual measuring methods, is transferred to digital photogrammetry with high technology development. Especially, the movement of target points is able to be measured in real-time automatically because it can be obtained 3-dimensional coordinates by digital photogrammetry. The use of automatic measuring methods has been researched in several different industries (Hannah, 1989; Lee et al., 2006). The applications of digital photogrammetry are increased in various civil engineering structures (Han et al., 2001; Han & Song, 2003; Han et al., 2007, 2008). It shows that the automatic and high-tech measuring system likeVisual Monitoring System (VMS) based on digital photogrammetry is able to apply to the stability evaluations of large civil engineering structures.

Most of recent measurement methods are based on image process method even though in some case, Global Positioning System (GPS) is used like the measurement of the deformation on the surface of large civil engineering structures (Stewart & Tsakiri, 2001). Also, automatic measuring method begins to use for stability evaluations of civil engineering structures; for examples, there are slope failure prediction (Han et al., 2001; Han & Song, 2003), displacement measurement (Bae, 2000; Kang et. al, 1995), monitoring of dams(Park et. al 2001; Han et. al, 2005). However, the current measuring systems like total station based on manual measuring are almost not possible to measure the movements of

<sup>\*</sup> Corresponding Author

Application of a Photogrammetric System for Monitoring Civil Engineering Structures 75

automatic system of industrial (Hannah, 1989; Lee et al., 2006). Also, the user interface design using digital photogrammetry technique was able to apply in high accuracy

The 3-dimensional measuring system based on existing photogrammetry is used in film with sensitive emulsion. However, the technique takes a time to respond to the risk in spite of great accuracy. Therefore, real-time measuring system, which improved measuring system based on existing photogrammetry, was requested for civil engineering structure

Photogrammetry provides the 3-dimensinal coordinates of unknown points from acquired multiple images, which are images of the same scene on different viewpoints. Photogrammetry procedure has object decision, image acquisition, image processing and analysis. The image acquisition of the past photogrammetry is used in film with sensitive emulsion. Nowadays, those are used in CCD and CMOS cameras. The 3-dimensinal coordinate precision of images depends on various factors like object condition, camera calibration and image orientation. That is, the scale and pixel size of image based on CCD and CMOS cameras is important factor in the image acquisition of photogrammetry. This means that camera calibration needs to enhance image accuracy (Kraus, 1993; 1997; 2007). In present, the digital images are produced by electric sensor of metric cameras based on CCD or CMOS, as above mentioned. The mathematical-geometric parameters of digital image based on principal distance, coordinates and principal point are defined as the factors of interior orientation. Even though geometric parameters represent the photogrammetry analysis model, it does not correspond to real object due to distortion of camera lens. Therefore, the camera calibration must be conducted to achieve the highest accuracy of model (Kraus, 1993; 1997).

In order to create 3-dimensinal coordinates of image, the image plane is produced by electric sensor in focal plane of cameras. The orientation parameters based on image plane can be calculated using collinearity equations (see Kraus, 1993) and then the 3-dimensinal

VMS is monitoring system using digital photogrammetry and it is made to analyze deformation of object based on real-time visualization. This section introduces composition,

The past photogrammetry using films makes a 3-dimensinal image by image acquisition, drawing, analysis and 3-dimensinal coordinate creation. A coordinate conversion of film image is conducted by coordinate formation program. It results in conversion process and visualization program and then it forms 3-dimensinal coordinates. The past photogrammetry has a problem for an immediate maintenance about deformation and displacement of structure in field because it requires a lot of processing time. If disaster risk

coordinates are produced (Kraus, 1993; 1997; 2007; Ohnishi et al., 2006).

happened, it would require a lot of time to establish countermeasure.

**3. Visual Monitoring System (VMS)** 

principle and process of VMS.

**3.1 Composition of VMS** 

that specially requires both economical, rapid reaction and high accuracy.

measuring system and vision system.

**2.2 Short-overview of digital photogrammetry** 

civil engineering structures in real-time based due to various field conditions even though most of measuring systems have a high accuracy. For example, the manual measuring method requires a lot of analyzing time for measured data because it has several procedures like photographing, drawing and analysis manually.

In the late 21th century, the image acquisition apparatus with high technology has been developed continuously and rapidly. If real-time automatic measuring system based on high technology is developed, the measuring system technique can be developed with digital image technique rapidly as well. It means that stability and maintenance technique for civil engineering structure can be more epochal improved in the future.

Therefore, this chapter introduces a real-time measuring system, VMS which is based on digital photogrammetry. The measuring results of VMS are compared with those of manual apparatus in various tests and then the accuracy of VMS is evaluated. At first, background of digital photogrammetry and VMS process are explained. Secondly, laboratory and field tests using VMS and cultural assets restoration based on application of digital photogrammetry are described. Finnally, conclusions about various tests and case study are summarized.

## **2. Background of digital photogrammetry**

### **2.1 Historical background**

The past photogrammetry requires several steps to obtain the adequate results which are divided into photographing, drawing, analysis, 3-dimensinal coordinates acquisition and conversion, because it uses films that have sensitive emulsion. Therefore, the past photogrammetry has problems in both the application of real-time measuring and distortion and storage of data.

In the late 20th century, CCD camera was introduced as image acquisition apparatus because CCD camera could not only be economically purchased but also, easily process and save the image data. The image acquisition apparatus has been developed in high resolution and wide analysis range based on the development of electric and electron. Also, the accuracy of camera lens has been improved by correction technique of geometric distortion and establishment of analysis algorithm (Fraser, 1997).

In the early 1990s, the image analysis techniques with film scan started to apply to various fields. In the mid-1990s, several researchers have studied the improvement of accuracy in image analysis techniques using establishment of analysis algorithm and commercialization of real-time measuring (El-Hakim & Wong, 1990). Furthermore, the 3-dimensional position measuring has been researched to apply the field of photogrammetry (Fraser, 1993; Shortis & Fraser, 1998). The correction of multi-focus lens has been studied to apply in close range photogrammetry (Munjy, 1985; 1986). The lens correction and image analysis improvement of CCD camera have been studied by using research results (Shortis et al., 1994) of close range photogrammetry and focus lens (Lichti & Chapman, 1995). CCD camera has been used in image analysis of robot vision and position decision of targets (Gruen, 1992).

The study of combination programs has been a trend, so separate image processing programs could be combined by using visual analysis and connection analysis based on existing researches. Especially, the photogrammetry that uses automatic technique of 3 dimensional data acquisition has been studied in the application of object movement and automatic system of industrial (Hannah, 1989; Lee et al., 2006). Also, the user interface design using digital photogrammetry technique was able to apply in high accuracy measuring system and vision system.

The 3-dimensional measuring system based on existing photogrammetry is used in film with sensitive emulsion. However, the technique takes a time to respond to the risk in spite of great accuracy. Therefore, real-time measuring system, which improved measuring system based on existing photogrammetry, was requested for civil engineering structure that specially requires both economical, rapid reaction and high accuracy.

#### **2.2 Short-overview of digital photogrammetry**

74 Special Applications of Photogrammetry

civil engineering structures in real-time based due to various field conditions even though most of measuring systems have a high accuracy. For example, the manual measuring method requires a lot of analyzing time for measured data because it has several procedures

In the late 21th century, the image acquisition apparatus with high technology has been developed continuously and rapidly. If real-time automatic measuring system based on high technology is developed, the measuring system technique can be developed with digital image technique rapidly as well. It means that stability and maintenance technique

Therefore, this chapter introduces a real-time measuring system, VMS which is based on digital photogrammetry. The measuring results of VMS are compared with those of manual apparatus in various tests and then the accuracy of VMS is evaluated. At first, background of digital photogrammetry and VMS process are explained. Secondly, laboratory and field tests using VMS and cultural assets restoration based on application of digital photogrammetry are

The past photogrammetry requires several steps to obtain the adequate results which are divided into photographing, drawing, analysis, 3-dimensinal coordinates acquisition and conversion, because it uses films that have sensitive emulsion. Therefore, the past photogrammetry has problems in both the application of real-time measuring and distortion

In the late 20th century, CCD camera was introduced as image acquisition apparatus because CCD camera could not only be economically purchased but also, easily process and save the image data. The image acquisition apparatus has been developed in high resolution and wide analysis range based on the development of electric and electron. Also, the accuracy of camera lens has been improved by correction technique of geometric distortion

In the early 1990s, the image analysis techniques with film scan started to apply to various fields. In the mid-1990s, several researchers have studied the improvement of accuracy in image analysis techniques using establishment of analysis algorithm and commercialization of real-time measuring (El-Hakim & Wong, 1990). Furthermore, the 3-dimensional position measuring has been researched to apply the field of photogrammetry (Fraser, 1993; Shortis & Fraser, 1998). The correction of multi-focus lens has been studied to apply in close range photogrammetry (Munjy, 1985; 1986). The lens correction and image analysis improvement of CCD camera have been studied by using research results (Shortis et al., 1994) of close range photogrammetry and focus lens (Lichti & Chapman, 1995). CCD camera has been

used in image analysis of robot vision and position decision of targets (Gruen, 1992).

The study of combination programs has been a trend, so separate image processing programs could be combined by using visual analysis and connection analysis based on existing researches. Especially, the photogrammetry that uses automatic technique of 3 dimensional data acquisition has been studied in the application of object movement and

for civil engineering structure can be more epochal improved in the future.

described. Finnally, conclusions about various tests and case study are summarized.

like photographing, drawing and analysis manually.

**2. Background of digital photogrammetry** 

and establishment of analysis algorithm (Fraser, 1997).

**2.1 Historical background** 

and storage of data.

Photogrammetry provides the 3-dimensinal coordinates of unknown points from acquired multiple images, which are images of the same scene on different viewpoints. Photogrammetry procedure has object decision, image acquisition, image processing and analysis. The image acquisition of the past photogrammetry is used in film with sensitive emulsion. Nowadays, those are used in CCD and CMOS cameras. The 3-dimensinal coordinate precision of images depends on various factors like object condition, camera calibration and image orientation. That is, the scale and pixel size of image based on CCD and CMOS cameras is important factor in the image acquisition of photogrammetry. This means that camera calibration needs to enhance image accuracy (Kraus, 1993; 1997; 2007).

In present, the digital images are produced by electric sensor of metric cameras based on CCD or CMOS, as above mentioned. The mathematical-geometric parameters of digital image based on principal distance, coordinates and principal point are defined as the factors of interior orientation. Even though geometric parameters represent the photogrammetry analysis model, it does not correspond to real object due to distortion of camera lens. Therefore, the camera calibration must be conducted to achieve the highest accuracy of model (Kraus, 1993; 1997).

In order to create 3-dimensinal coordinates of image, the image plane is produced by electric sensor in focal plane of cameras. The orientation parameters based on image plane can be calculated using collinearity equations (see Kraus, 1993) and then the 3-dimensinal coordinates are produced (Kraus, 1993; 1997; 2007; Ohnishi et al., 2006).

## **3. Visual Monitoring System (VMS)**

VMS is monitoring system using digital photogrammetry and it is made to analyze deformation of object based on real-time visualization. This section introduces composition, principle and process of VMS.

#### **3.1 Composition of VMS**

The past photogrammetry using films makes a 3-dimensinal image by image acquisition, drawing, analysis and 3-dimensinal coordinate creation. A coordinate conversion of film image is conducted by coordinate formation program. It results in conversion process and visualization program and then it forms 3-dimensinal coordinates. The past photogrammetry has a problem for an immediate maintenance about deformation and displacement of structure in field because it requires a lot of processing time. If disaster risk happened, it would require a lot of time to establish countermeasure.

Application of a Photogrammetric System for Monitoring Civil Engineering Structures 77

Digital image processing has a procedure of threshold, histogram, contour extraction and image noise removal works. The image processing (in more detail, see Pratt, 1991) is

Image processing data is classified as colour image, gray image and binary image. Binary image can show an essential scene in the boundary value of black and white colour. That is why binary image is mostly applied to image processing even though it was not colour image. In general, colour image (original image, Fig 3(a)) can be converted to binary image,

Histogram is very important work to show the contrast information of the image. The histogram shows the distribution of the light and shade value in image. It simply presents

Line extraction is to be defined as not only outline of object in the image, but also characteristic line of the image on image processing. The line extraction to present the characteristic of the image is important tool in common with histogram. Line extraction

If the image has noise, there is a clear difference between noise depth and its surroundings in the image. The noise removal using noise characteristic is defined as smoothing method.

Fig. 2. Measuring analysis procedure of VMS

by applying threshold work as shown in Fig. 3(b).

Also, the noise removal can improve image quality.

**3.2.1 Digital image processing** 

2. Histogram and line extraction

image is shown in Fig 3(c) 3. Image noise removal

an image pixel using bar graph as well.

summarized as followed;

1. Threshold

The VMS photogrammetry analysis software which combine with 3-dimensional coordinate extraction, drawing and analysis, can analyze structural deformation as shown in Fig. 1. The VMS as a unified program is real-time measuring system for civil engineering structure with using digital photogrammetry. VMS can evaluate the structural stability by comparing the continuous obtained information to the existing information of structure. Also, it is real-time monitoring system for maintenance of structure.

Fig. 1. Analysis procedure of VMS using digital photogrammetry

## **3.2 Process of VMS**

The procedure of VMS is shown in Fig. 2. First of all, the image obtained from digital camera is conducted by image processing. Secondly, the modified image compares with the selected model image. Then it searches the model in the image. Finally, the measuring result is obtained by the searched result using image analysis module.

VMS is developed windows based program by Delphi and it consists of five tools as followed;

	- Input focal length, pixel size and position (3-dimensinal coordinates) of cameras, and information of reference and unknown points
	- Select size, range and area center of model for photogrammetry analysis, then modify the selected model using image processing wok
	- Analyze measuring data using the combined photogrammetry analysis software

Fig. 2. Measuring analysis procedure of VMS

#### **3.2.1 Digital image processing**

Digital image processing has a procedure of threshold, histogram, contour extraction and image noise removal works. The image processing (in more detail, see Pratt, 1991) is summarized as followed;

1. Threshold

76 Special Applications of Photogrammetry

The VMS photogrammetry analysis software which combine with 3-dimensional coordinate extraction, drawing and analysis, can analyze structural deformation as shown in Fig. 1. The VMS as a unified program is real-time measuring system for civil engineering structure with using digital photogrammetry. VMS can evaluate the structural stability by comparing the continuous obtained information to the existing information of structure. Also, it is real-time

monitoring system for maintenance of structure.

Fig. 1. Analysis procedure of VMS using digital photogrammetry

obtained by the searched result using image analysis module.

1. Project tool has camera information to photogrammetry

2. Second tool select analysis model

and information of reference and unknown points

modify the selected model using image processing wok

4. Fifth tool performs photogrammetry analysis and sees analysis results.

The procedure of VMS is shown in Fig. 2. First of all, the image obtained from digital camera is conducted by image processing. Secondly, the modified image compares with the selected model image. Then it searches the model in the image. Finally, the measuring result is

VMS is developed windows based program by Delphi and it consists of five tools as




3. Third and fourth tools find metric image and model position in image, respectively - Search the modified model of mertic image using geometric model finder

**3.2 Process of VMS** 

followed;

Image processing data is classified as colour image, gray image and binary image. Binary image can show an essential scene in the boundary value of black and white colour. That is why binary image is mostly applied to image processing even though it was not colour image. In general, colour image (original image, Fig 3(a)) can be converted to binary image, by applying threshold work as shown in Fig. 3(b).

2. Histogram and line extraction

Histogram is very important work to show the contrast information of the image. The histogram shows the distribution of the light and shade value in image. It simply presents an image pixel using bar graph as well.

Line extraction is to be defined as not only outline of object in the image, but also characteristic line of the image on image processing. The line extraction to present the characteristic of the image is important tool in common with histogram. Line extraction image is shown in Fig 3(c)

3. Image noise removal

If the image has noise, there is a clear difference between noise depth and its surroundings in the image. The noise removal using noise characteristic is defined as smoothing method. Also, the noise removal can improve image quality.

Application of a Photogrammetric System for Monitoring Civil Engineering Structures 79

The characteristic extraction is the selecting process of the stabilized physical property for data transformation. Furthermore, the process includes both removal of redundancy property without loss of data information by reduction of pattern dimension and minimization of the processing time and storage space to pattern recognition. It means that the obtained data by measuring are converted into the required characteristics for pattern recognition. The methods of pattern matching, which is to identify the range of random pattern in the image, are theoretical analysis and structural analysis. Fig. 5 shows example in

a) b)

c) d)

Fig. 5. Flow of pattern recognition system: a) original model, b) preprocessing & data extraction, c) identification & pattern recognition, d) model search result (blue-reference

flow of pattern recognition system.

Fig. 4. Pattern recognition procedure

point, red-unkown poins)

Fig. 3. Step of Digital image processing: a) original image, b) binary image applied in threshold; c) line extraction image

#### **3.2.2 Model finding**

The geometric model finder module is used in photogrammetry procedures because the model finding needs to search an unknown points corresponding to reference point. The function of geometric model finder module only extracts the required data from pattern recognition system based on the modified image by image processing. The characteristics of extracted data are distinguished by pre-processing. Then its pattern is recognized and processed by system. That is, VMS requires a pattern recognition procedure because it is automatic and complex system.

The procedure of pattern recognition is shown in Fig. 4. The metric image is pre-processed to pull out the required data because it includes unnecessary information. Next, the extracted data is divided into smaller units for facilitation of pattern recognition. Small units are idealized in both size and length. Finally, the characteristics are selected to obtain the important factors of pattern recognition, and then it is compared to the identification of patterns.

The pattern preprocessing includes preprocessing, partition and normalization. It is simple and does not require a lot of time in process. It does not change the required characteristics in pattern recognition.

The characteristic extraction is the selecting process of the stabilized physical property for data transformation. Furthermore, the process includes both removal of redundancy property without loss of data information by reduction of pattern dimension and minimization of the processing time and storage space to pattern recognition. It means that the obtained data by measuring are converted into the required characteristics for pattern recognition. The methods of pattern matching, which is to identify the range of random pattern in the image, are theoretical analysis and structural analysis. Fig. 5 shows example in flow of pattern recognition system.


Fig. 4. Pattern recognition procedure

78 Special Applications of Photogrammetry

a) b)

c)

The geometric model finder module is used in photogrammetry procedures because the model finding needs to search an unknown points corresponding to reference point. The function of geometric model finder module only extracts the required data from pattern recognition system based on the modified image by image processing. The characteristics of extracted data are distinguished by pre-processing. Then its pattern is recognized and processed by system. That is, VMS requires a pattern recognition procedure because it is

The procedure of pattern recognition is shown in Fig. 4. The metric image is pre-processed to pull out the required data because it includes unnecessary information. Next, the extracted data is divided into smaller units for facilitation of pattern recognition. Small units are idealized in both size and length. Finally, the characteristics are selected to obtain the important factors of pattern recognition, and then it is compared to the identification of

The pattern preprocessing includes preprocessing, partition and normalization. It is simple and does not require a lot of time in process. It does not change the required characteristics

Fig. 3. Step of Digital image processing: a) original image, b) binary image applied in

threshold; c) line extraction image

automatic and complex system.

**3.2.2 Model finding** 

patterns.

in pattern recognition.

Fig. 5. Flow of pattern recognition system: a) original model, b) preprocessing & data extraction, c) identification & pattern recognition, d) model search result (blue-reference point, red-unkown poins)

Application of a Photogrammetric System for Monitoring Civil Engineering Structures 81

a) b) c)

Fig. 7. View of welded member: a) welded member marked measuring points, b) tensile test

To verify the accuracy and the applicability of VMS and investigate the characteristics of the deformation behaviour in a welded joint, strain values are calculated at each measuring points. Strains at each measuring point are shown in Fig. 8. Syt is VMS's overall strain values of a test member corresponding to those measured by a test instrument (MTS-810). Sxu1~Sxu10 and Syu1~Syu10 are strain values at upper part in the x-direction and the ydirection. Sxl1~Sxl10 and Syl1~Syl10 are strain values at lower part in the x-direction and

The loading tests are conducted using MTS-810, which has loading capacity of 250kN. The loading increasement is controlled by tensile displacement at a 0.01 mm/sec with the assumption of static deformation. Also, the deformation is measured by two sets of digital camera, which are located at distance of 2.1m. VMS measures the deformation of measuring points at each 50 second. Fig. 7 shows a welded member marked measuring points and

To confirm the accuracy and the applicability of VMS, strain (Syt) values of VMS are compared with those of a test instrument (MTS-810) as shown in Fig. 8. Syt values measured by VMS are good agreement with a stress-strain curve measured by MTS at the elastic and at the plastic regions. And it is seen that the developed VMS can accurately measure an overall deformation of a test member. It is concluded that the developed VMS has the high accuracy of 90% and the applicability of deformation measurement for the

rig, c) Strain models

the y-direction.

welded members.

tensile test rig (Han et al., 2008).

**4.1.2 Comparison of results and analysis** 

*x*

*y*

syt

sxu1sxu2 sxu3 sxu4 syu1 syu2 syu3 syu5

syu4

sxl1 sxl2 sxl3 sxl4 syl1 syl2 syl3 syl4 syl5

## **4. Experimental investigation using VMS**

Digital photogrammetry is applied in various fields. VMS has an important role for the deformation measuring of civil engineering structures as well as historic preservation and restoration of cultural assets.

The VMS results of tensile strength tests for welded members in civil structure, friction tests for concrete masonry block (CMU) retaining wall in civil engineering structure, and the measured deformations of cultural assets are presented.

#### **4.1 Deformation measuring of welded members**

The VMS and a test instrument (MTS-810) are used for the deformation measuring of the tensile strength tests of welded members. The accuracy and applicability was verified with comparing the deformation values of VMS to those of a test instrument. The characteristics of the behaviour in a welded joint were investigated by using VMS.

#### **4.1.1 Loading test**

In order to measure the local and overall deformations, measuring points are marked at a welded member as shown in both Fig. 6 and Fig. 7. U0 and L0 are measuring points to observe the overall deformation of the test member. U1~U10 and L1~L10 are measuring points to observe the local deformation near a welded joint at upper and lower part.

Fig. 6. Marked measuring points in welded member

Digital photogrammetry is applied in various fields. VMS has an important role for the deformation measuring of civil engineering structures as well as historic preservation and

The VMS results of tensile strength tests for welded members in civil structure, friction tests for concrete masonry block (CMU) retaining wall in civil engineering structure, and the

The VMS and a test instrument (MTS-810) are used for the deformation measuring of the tensile strength tests of welded members. The accuracy and applicability was verified with comparing the deformation values of VMS to those of a test instrument. The characteristics

In order to measure the local and overall deformations, measuring points are marked at a welded member as shown in both Fig. 6 and Fig. 7. U0 and L0 are measuring points to observe the overall deformation of the test member. U1~U10 and L1~L10 are measuring

+ : Measuring point

Lower part Upper part

*y*

U0

U1 U2 U3 U4 U5

*x*

U6 U7 U8 U9 U10

L0

points to observe the local deformation near a welded joint at upper and lower part.

L1 L2 L3 L4 L5

L6 L7 L8 L9 L10

**4. Experimental investigation using VMS** 

measured deformations of cultural assets are presented.

of the behaviour in a welded joint were investigated by using VMS.

**4.1 Deformation measuring of welded members** 

230 mm 10 mm

Fig. 6. Marked measuring points in welded member

Grip line

Grip line

4@15 mm

restoration of cultural assets.

**4.1.1 Loading test** 

Upper part

Lower part

135 mm

90 mm

Fig. 7. View of welded member: a) welded member marked measuring points, b) tensile test rig, c) Strain models

To verify the accuracy and the applicability of VMS and investigate the characteristics of the deformation behaviour in a welded joint, strain values are calculated at each measuring points. Strains at each measuring point are shown in Fig. 8. Syt is VMS's overall strain values of a test member corresponding to those measured by a test instrument (MTS-810). Sxu1~Sxu10 and Syu1~Syu10 are strain values at upper part in the x-direction and the ydirection. Sxl1~Sxl10 and Syl1~Syl10 are strain values at lower part in the x-direction and the y-direction.

The loading tests are conducted using MTS-810, which has loading capacity of 250kN. The loading increasement is controlled by tensile displacement at a 0.01 mm/sec with the assumption of static deformation. Also, the deformation is measured by two sets of digital camera, which are located at distance of 2.1m. VMS measures the deformation of measuring points at each 50 second. Fig. 7 shows a welded member marked measuring points and tensile test rig (Han et al., 2008).

#### **4.1.2 Comparison of results and analysis**

To confirm the accuracy and the applicability of VMS, strain (Syt) values of VMS are compared with those of a test instrument (MTS-810) as shown in Fig. 8. Syt values measured by VMS are good agreement with a stress-strain curve measured by MTS at the elastic and at the plastic regions. And it is seen that the developed VMS can accurately measure an overall deformation of a test member. It is concluded that the developed VMS has the high accuracy of 90% and the applicability of deformation measurement for the welded members.

Application of a Photogrammetric System for Monitoring Civil Engineering Structures 83

**4.2 Displacement measuring of reinforced concrete masonry unit (CMU) retaining wall**  The manual measuring apparatuses like displacement transducer, settlement meter and total station are applied to perform both stability evaluation and maintenance of the reinforced CMU retaining wall. However, it is difficult to measure the overall deformation and crack of the reinforced CMU retaining wall because most manual measuring system can only measure the partial deformations. Also, the manual measuring systems have some disadvantages in durability and maintenance of apparatuses due to malfunctions. The malfunctions cause low accuracy for immediate reaction. Therefore, VMS is one of the good solutions for reasonable measuring of the reinforced CMU retaining wall because it can solve the disadvantages of the existing measuring systems. The forced displacement laboratory test of the reinforced CMU retaining wall is conducted to evaluate both the behaviour of reinforced CMU retaining wall and real-time measuring system at a long

**4.2.1 Forced displacement laboratory test of reinforced CMU wall facing units** 

when vertical load is applied to the wall facing units

4. Obtain 3-dimensional coordinates from cameras using total station

Measuring both local displacement and overall deformation of CMU retaining wall facing units in real scale is performed. The test procedure is shown in Fig. 10 and follows as;

1. The rubber mats (like soft ground) is located to lead settlement of the wall facing units

2. The wall facing units with three tiers is located on rubber mats of laboratory test

a) b)

c) d)

Fig. 10. Test procedure: a) initial coordinates measuring (total station & VMS), b) loading,

3. Obtain initial 3-dimensional coordinates of the image using VMS and total station

6. Obtain the deformed image coordinates of left and right due to the applied loads

distance.

apparatus

5. Apply loads on the wall facing units

c) displacement measuring, d) end of test

Fig. 8. Comparison of overall strains between VMS and MTS-810

Fig. 9. Comparsion of strain distribution in a welded joint at upper part.

Strain values near a welded joint at upper part are shown Fig. 9. Strain values (Sxu1~Sxu4) in the x-direction show compressive (-) up to -0.02 in the elastic region. In the plastic region, strain values constantly keep compressive. In the y-direction strain values (Syu1~Sxu5) are tensile (+) about +0.01 in the elastic region. In the plastic region, strain values are rapidly larger up to about +0.06.

It is shown from VMS measuring observations for a welded joint that strain values in the xdirection keep compressive up to -0.02. Strain values in the y-direction are tensile and rapidly increased up to +0.06 in the plastic region.

#### **4.2 Displacement measuring of reinforced concrete masonry unit (CMU) retaining wall**

The manual measuring apparatuses like displacement transducer, settlement meter and total station are applied to perform both stability evaluation and maintenance of the reinforced CMU retaining wall. However, it is difficult to measure the overall deformation and crack of the reinforced CMU retaining wall because most manual measuring system can only measure the partial deformations. Also, the manual measuring systems have some disadvantages in durability and maintenance of apparatuses due to malfunctions. The malfunctions cause low accuracy for immediate reaction. Therefore, VMS is one of the good solutions for reasonable measuring of the reinforced CMU retaining wall because it can solve the disadvantages of the existing measuring systems. The forced displacement laboratory test of the reinforced CMU retaining wall is conducted to evaluate both the behaviour of reinforced CMU retaining wall and real-time measuring system at a long distance.

#### **4.2.1 Forced displacement laboratory test of reinforced CMU wall facing units**

Measuring both local displacement and overall deformation of CMU retaining wall facing units in real scale is performed. The test procedure is shown in Fig. 10 and follows as;


82 Special Applications of Photogrammetry

elastic region ← → platic region

elastic region ← → platic region

0 0.005 0.01 0.015 0.02 Strain (measured by MTS-810)

Strain values near a welded joint at upper part are shown Fig. 9. Strain values (Sxu1~Sxu4) in the x-direction show compressive (-) up to -0.02 in the elastic region. In the plastic region, strain values constantly keep compressive. In the y-direction strain values (Syu1~Sxu5) are tensile (+) about +0.01 in the elastic region. In the plastic region, strain values are rapidly

It is shown from VMS measuring observations for a welded joint that strain values in the xdirection keep compressive up to -0.02. Strain values in the y-direction are tensile and

Fig. 9. Comparsion of strain distribution in a welded joint at upper part.

0 0.005 0.01 0.015 0.02 Strain

Syt (measured by VMS)

Syu1 Syu2 Syu3 Syu4 Syu5 Sxu1 Sxu2 Sxu3 Sxu4

Stress-strain curve (measured by MTS-810)

0


rapidly increased up to +0.06 in the plastic region.

larger up to about +0.06.

0

0.02

0.04

Strain (measured by VMS)

0.06

0.08

Fig. 8. Comparison of overall strains between VMS and MTS-810

100

200

Stress (MPa)

300

400

6. Obtain the deformed image coordinates of left and right due to the applied loads

Fig. 10. Test procedure: a) initial coordinates measuring (total station & VMS), b) loading, c) displacement measuring, d) end of test

Application of a Photogrammetric System for Monitoring Civil Engineering Structures 85

The test results confirm the applicability of VMS as a good measuring system to the reinforced CMU retaining wall. Furthermore, the analysis results show that VMS can be real-time measuring systems while the targets are moved. Therefore, it is suggested that VMS can be a reasonable measuring method for reinforced CMU retaining wall systems.

Total station value VMS value Total

Case I 99563.024 99785.000 -101886.499 99565.948 99784.041 -101887.468 **11.045 12.891 -1.846**  Case II 99563.721 99780.000 -101885.782 99566.378 99779.270 -101888.247 **16.062 17.657 -1.594**  Case III 99563.024 99774.000 -101886.499 99565.159 99773.080 -101887.266 **22.023 23.852 -1.829**  Case IV 99584.871 99796.000 -101881.232 99587.203 99793.754 -101882.211 **21.954 22.587 -0.633**  Case V 99594.093 99794.000 -101883.220 99596.535 99793.994 -101882.876 **30.676 31.478 -0.802**  Case VI 99594.072 99778.000 -101881.806 99597.074 99776.993 -101883.318 **35.679 37.526 -1.847**  Omission of measuring results (number 8, 9, 10, 11, 12, 14 and 17)

Case I 99377.987 99253.000 -101903.326 99378.143 99250.941 -101904.537 **13.077 11.706 1.370**  Case II 99377.987 99249.000 -101903.326 99377.975 99246.205 -101903.625 **17.059 16.476 0.583**  Case III 99378.704 99242.000 -101904.023 99378.180 99238.361 -101903.756 **24.021 24.303 -0.282**  Case IV 99398.419 99266.000 -101898.079 99398.882 99260.212 -101898.850 **21.471 22.029 -0.558**  Case V 99409.076 99263.000 -101901.461 99408.924 99260.369 -101901.005 **31.385 31.430 -0.045**  Case VI 99409.055 99246.000 -101900.047 99409.954 99242.347 -101900.917 **37.229 38.214 -0.985** 

> Test case Case I Case II Case III Case IV Case V Case VI

\* Case I: vertical load 30kN, Case II: vertical load 40kN, Case III: vertical load 50kN, Case IV: arbitrary horizontal displacement (1), Case V: arbitrary horizontal displacement(2), Case VI: vertical load and

7 16.7 9.9 8.3 2.9 2.6 5.2 8 8.9 3.3 4.4 1.3 0.5 3.9 9 1.1 1.0 3.5 3.8 0.9 2.4 10 2.7 2.4 2.0 6.7 2.3 2.3 11 8.7 4.6 7.2 2.3 2.7 5.0 12 1.2 1.3 3.6 3.9 2.4 3.8 14 0.8 0.5 6.5 2.1 1.7 5.4 16 10.5 3.4 1.2 2.6 0.1 2.6 17 1.8 0.8 0.4 4.7 0.3 0.6 **Average 5.8 3.0 4.1 3.4 1.5 3.5** 

Table 1. Comparison between total station and VMS in measuring results

Table 2. Measuring difference according to test cases (%)

x Y z x' y' z'

coord. 99563.742 99796.000 -101887.196 99565.638 99796.911 -101888.142

coord. 99378.007 99266.000 -101904.740 99377.803 99262.640 -101904.771

station disp. (mm)

VMS disp. (mm)

Disp. subtraction (mm)

Unknown point

7

16

Test classification

Ini.

Ini.

horizontal displacement

Unknown point

The six tests are conducted. There are three measurments in vertical direction, two in horizontal measuring, and one simultanuous measuring in both vertical and horizontal directions. The test procedure is repeated at each case. The reference target points on steel frame of laboratory test apparatus and the unknown target points on the renforced CMU retaining wall face are located respectively as shown in Fig. 11. The movements of the target points are monitored by both total station and VMS (refer Fig. 12). The vertical loads apply from 30kN to 50kN and the vertical displacements are measured. The horizontal displacements occur due to the forced movement of rubber mats (Han et al., 2006).

Fig. 11. Front view of the fixed targets on steel frame and CMU

Fig. 12. View of CCD cameras and computer system with VMS: a) left; b) right

#### **4.2.2 Comparison of results and analysis**

The initial coordinate for six reference target points and nine unknown target points is obtained by both VMS and total station. The displacements of wall facing units by vertical load and forced displacement are measured. The test results are shown in Table 1. However, the measuring results of target points 13, 15 and 18 are eliminated because of dropping the target points off wall facing units during tests. The measuring difference between total station and VMS is from 0.1% to 16.7%. Therefore, the measuring results of unknown points are only presented the maximum and minimum differences as shown in Table 1. The average difference of total results is less than 3.6% as shown in Table 2.

The six tests are conducted. There are three measurments in vertical direction, two in horizontal measuring, and one simultanuous measuring in both vertical and horizontal directions. The test procedure is repeated at each case. The reference target points on steel frame of laboratory test apparatus and the unknown target points on the renforced CMU retaining wall face are located respectively as shown in Fig. 11. The movements of the target points are monitored by both total station and VMS (refer Fig. 12). The vertical loads apply from 30kN to 50kN and the vertical displacements are measured. The horizontal

a) b)

The initial coordinate for six reference target points and nine unknown target points is obtained by both VMS and total station. The displacements of wall facing units by vertical load and forced displacement are measured. The test results are shown in Table 1. However, the measuring results of target points 13, 15 and 18 are eliminated because of dropping the target points off wall facing units during tests. The measuring difference between total station and VMS is from 0.1% to 16.7%. Therefore, the measuring results of unknown points are only presented the maximum and minimum differences as shown in Table 1. The

Fig. 12. View of CCD cameras and computer system with VMS: a) left; b) right

average difference of total results is less than 3.6% as shown in Table 2.

displacements occur due to the forced movement of rubber mats (Han et al., 2006).

Fig. 11. Front view of the fixed targets on steel frame and CMU

**4.2.2 Comparison of results and analysis** 

The test results confirm the applicability of VMS as a good measuring system to the reinforced CMU retaining wall. Furthermore, the analysis results show that VMS can be real-time measuring systems while the targets are moved. Therefore, it is suggested that VMS can be a reasonable measuring method for reinforced CMU retaining wall systems.


\* Case I: vertical load 30kN, Case II: vertical load 40kN, Case III: vertical load 50kN, Case IV: arbitrary horizontal displacement (1), Case V: arbitrary horizontal displacement(2), Case VI: vertical load and horizontal displacement

Table 1. Comparison between total station and VMS in measuring results


Table 2. Measuring difference according to test cases (%)

Application of a Photogrammetric System for Monitoring Civil Engineering Structures 87

reference target points (numbered as 1, 3, 4, 6, 7 and 9) and unknown target points (numbered as 2, 5 and 8) are located on the face of concrete bleacher, respectively (refer Fig. 13 and Fig. 14). The deformation of the targets points are measured by VMS system. As there was not a actual structural displacement for measuring, the unknown points have a simulated movement from initial position by the forced displacement as shown in Fig. 15. The forced displacement of targets points assumes 5cm at top and bottom and 9cm at left and right. Therefore, the each unknown point is measured in total of four steps. The

3. Obtain initial 3-dimensional coordinates of the image using both VMS and total station

a) b)

Fig. 16. View of CCD cameras and computer system with VMS: a) left, b) right

simulation procedure is followed as;

Fig. 15. Forced displacement of target

6. Repeat (5) process according to the each step

1. Set up the CCD cameras and prepare VMS system (refer Fig. 16)

4. Obtain 3-dimensional coordinates of cameras using total station 5. Obtain images coordinates of left and right by forced displacement

2. Fix reference point and unknown point targets points on object and then

#### **4.3 Field application of VMS to real structure**

#### **4.3.1 Simulated field test**

The field test of VMS is conducted for the concrete wall (refer Fig. 13), which is made of concrete, because of the limitation of field application on large structure. The simulation idea comes from large civil engineering structures made from concrete materials (Han et al., 2007). The field test is conducted to evaluate VMS application to concrete structure at long distance. The results of VMS compares with those of total station.

Fig. 13. Simulation structure view for 3-dimensional image acquisition: a) left image, b) right image

Fig. 14. Simulation schematic

The targets points are located on the concrete bleacher at the distance around 76m to 97m from CCD cameras and the distance between cameras is 87.9m as show in Fig. 14. The reference target points (numbered as 1, 3, 4, 6, 7 and 9) and unknown target points (numbered as 2, 5 and 8) are located on the face of concrete bleacher, respectively (refer Fig. 13 and Fig. 14). The deformation of the targets points are measured by VMS system. As there was not a actual structural displacement for measuring, the unknown points have a simulated movement from initial position by the forced displacement as shown in Fig. 15. The forced displacement of targets points assumes 5cm at top and bottom and 9cm at left and right. Therefore, the each unknown point is measured in total of four steps. The simulation procedure is followed as;


86 Special Applications of Photogrammetry

The field test of VMS is conducted for the concrete wall (refer Fig. 13), which is made of concrete, because of the limitation of field application on large structure. The simulation idea comes from large civil engineering structures made from concrete materials (Han et al., 2007). The field test is conducted to evaluate VMS application to concrete structure at long

a) b) Fig. 13. Simulation structure view for 3-dimensional image acquisition: a) left image, b) right

The targets points are located on the concrete bleacher at the distance around 76m to 97m from CCD cameras and the distance between cameras is 87.9m as show in Fig. 14. The

**4.3 Field application of VMS to real structure** 

distance. The results of VMS compares with those of total station.

**4.3.1 Simulated field test** 

image

Fig. 14. Simulation schematic

Fig. 15. Forced displacement of target

Fig. 16. View of CCD cameras and computer system with VMS: a) left, b) right

Application of a Photogrammetric System for Monitoring Civil Engineering Structures 89

Recently, there have been many attempts to restore cultural assets in South Korea. However, both maintenance and restoration of cultural assets are very difficult due to several factors like site conditions, natural deteriorations, damages and restoration methods. Therefore, the photogrammetry methods based on 3-dimensonal analysis was introduced as non-contact

The case study presents the application of a digital photogrammetry to seven-story stone tower in Sinsedong, Gyeongsangbuk-do, Korea for the maintenance data establishment of

Fig. 17. Seven-story stone tower in Sinsedong, Gyeongsangbuk-do, Korea (Sin & Kim, 2006;

The targets are fixed considering obstacles around seven-story stone tower in Sinsedong, Gyeongsangbuk-do, Korea. The front and back images at the top, the middle and the bottom positions are measured by CCD cameras as shown in Fig. 18. 3-dimensional coordinates are obtained by the photogrammetry process based on acquired images and decided by RolleiMetric CDW (Close-range digital workstation). The drawing of seven-story stone

**4.4 Case study for cultural assets** 

methods without damage of cultural assets (Kim et al., 2003).

cultural assets as shown in Fig. 17 (Sin & Kim, 2006; Yoon, 2006).

**4.4.1 Overview** 

Yoon, 2006)

**4.4.2 Application result and analysis** 

tower is presented as shown in Fig. 19.

#### **4.3.2 Comparison of results and analysis**

The measuring results based on initial and forced displacement are analyzed as shown in Table 3 and 4. The initial coordinates of the image using both total station and VMS are almost identical as shown in Table 3. The initial displacements of total station and VMS are zero. Also, the displacement according to the forced displacement is measured by both total station and VMS. The results are shown in Table 4. The comparison of measuring results shows that the difference is from 0.325mm to 10.436mm irregularly. However, the accuracy of VMS is acceptable because the calculated difference range based on camera pixel and measuring distance has maximum 10.436mm.

It means that VMS can apply to measure displacement, deformation and crack of civil engineering structures. In addition, the accuracy of VMS will be improved continuously because the error rate in camera capacity will be decreased by the industrial development related to image acquisition apparatuses.


Table 3. Initial coordinates of targets


Table 4. Comparison results between Total station value and VMS value according to forced displacement

#### **4.4 Case study for cultural assets**

#### **4.4.1 Overview**

88 Special Applications of Photogrammetry

The measuring results based on initial and forced displacement are analyzed as shown in Table 3 and 4. The initial coordinates of the image using both total station and VMS are almost identical as shown in Table 3. The initial displacements of total station and VMS are zero. Also, the displacement according to the forced displacement is measured by both total station and VMS. The results are shown in Table 4. The comparison of measuring results shows that the difference is from 0.325mm to 10.436mm irregularly. However, the accuracy of VMS is acceptable because the calculated difference range based on camera pixel and

It means that VMS can apply to measure displacement, deformation and crack of civil engineering structures. In addition, the accuracy of VMS will be improved continuously because the error rate in camera capacity will be decreased by the industrial development

2 50732 104053 -173430 50797 104052 -173335 Unknown 3 66774 104083 -173912 66774 104083 -173912 reference 4 38404 101559 -166586 38404 101559 -166586 reference 5 51345 101437 -169566 51398 101445 -169534 Unknown 6 66096 101606 -169967 66096 101606 -169967 reference 7 36781 107416 -173733 36781 107416 -173733 reference 8 49892 107274 -176846 49971 107247 -176695 Unknown 9 66988 107393 -177548 66988 107393 -177548 reference

Total station value VMS value Total station

Step 2 51431 101483 -169592 51480 101498 -169554 99.664 101.073 -1.409 Step 3 51255 101483 -169545 51310 101497 -169511 104.771 102.619 2.153 Step 4 51253 101392 -169548 51309 101398 -169518 101.912 104.530 -2.619

Step 2 50816 104104 -173448 50883 104100 -173352 99.945 99.620 0.325 Step 3 50641 104104 -173408 50708 104098 -173310 103.257 106.287 -3.030 Step 4 50636 104017 -173415 50705 104008 -173311 104.766 103.350 1.416

Step 2 49978 107321 -176871 50050 107293 -176719 94.515 101.020 -6.505 Step 3 49796 107323 -176833 49882 107290 -176679 100.130 108.735 -8.605 Step 4 49799 107228 -176839 49884 107195 -176682 102.186 104.239 -2.052 Table 4. Comparison results between Total station value and VMS value according to forced

Total station value VMS value Point x y z x' y' z' classification

37491 104055 -170330 37491 104055 -170330 reference

(mm) x y z x' y' z'

51434 101386 -169592 51486 101401 -169558 101.272 106.049 -4.777

50814 104014 -173452 50888 104008 -173358 103.663 93.227 10.436

49979 107232 -176874 50060 107202 -176724 103.860 100.538 3.322

disp. (mm)

VMS disp. (mm)

Disp. subtraction

**4.3.2 Comparison of results and analysis** 

measuring distance has maximum 10.436mm.

related to image acquisition apparatuses.

Test step

Initial

Unknown point

5

2

8

Table 3. Initial coordinates of targets

Targets number

1

Test step

Step 1

Step 1

Step 1

displacement

Recently, there have been many attempts to restore cultural assets in South Korea. However, both maintenance and restoration of cultural assets are very difficult due to several factors like site conditions, natural deteriorations, damages and restoration methods. Therefore, the photogrammetry methods based on 3-dimensonal analysis was introduced as non-contact methods without damage of cultural assets (Kim et al., 2003).

The case study presents the application of a digital photogrammetry to seven-story stone tower in Sinsedong, Gyeongsangbuk-do, Korea for the maintenance data establishment of cultural assets as shown in Fig. 17 (Sin & Kim, 2006; Yoon, 2006).

Fig. 17. Seven-story stone tower in Sinsedong, Gyeongsangbuk-do, Korea (Sin & Kim, 2006; Yoon, 2006)

#### **4.4.2 Application result and analysis**

The targets are fixed considering obstacles around seven-story stone tower in Sinsedong, Gyeongsangbuk-do, Korea. The front and back images at the top, the middle and the bottom positions are measured by CCD cameras as shown in Fig. 18. 3-dimensional coordinates are obtained by the photogrammetry process based on acquired images and decided by RolleiMetric CDW (Close-range digital workstation). The drawing of seven-story stone tower is presented as shown in Fig. 19.

Application of a Photogrammetric System for Monitoring Civil Engineering Structures 91

a)

Fig. 18. Targets image acquisition according to each position: a) top, b) middle, c) bottom (Sin & Kim, 2006; Yoon, 2006)

a)

b)

c)

Fig. 18. Targets image acquisition according to each position: a) top, b) middle, c) bottom

(Sin & Kim, 2006; Yoon, 2006)

Application of a Photogrammetric System for Monitoring Civil Engineering Structures 93

The evaluation results are shown in Fig. 20. In front view, the incline and the maximum eccentricity are 1.3° and 0.336m on the left, respectively. In back view, the incline and the maximum eccentricity are 0.78° and 0.251m on the right, respectively. Therefore, the digital image information based on the results of photogrammetry analysis can be applied to space analysis like cross section and inclination. It means that digital photogrammetry can be used

a) b)

This chapter introduces research cases related to photogrammetry and a real-time measuring system (called as visual monitoring system, VMS) which is based on digital photogrammetry. It confirms the applicability of digital photogrammetry in civil

engineering structures and cultural assets. The research conclusions are followed as;

Fig. 20. Incline analysis results: a) front, b) back (Sin & Kim, 2006; Yoon, 2006)

**5. Conclusion** 

for stability evaluation, maintenance and restoration of cultural assets.

b)

Fig. 19. Drawing results of stone tower: a) front, b) back (Sin & Kim, 2006; Yoon, 2006)

The stability of the seven-story stone tower is evaluated by the results of photogrammetry analysis. The stability evaluation is as followed;


The evaluation results are shown in Fig. 20. In front view, the incline and the maximum eccentricity are 1.3° and 0.336m on the left, respectively. In back view, the incline and the maximum eccentricity are 0.78° and 0.251m on the right, respectively. Therefore, the digital image information based on the results of photogrammetry analysis can be applied to space analysis like cross section and inclination. It means that digital photogrammetry can be used for stability evaluation, maintenance and restoration of cultural assets.

Fig. 20. Incline analysis results: a) front, b) back (Sin & Kim, 2006; Yoon, 2006)

#### **5. Conclusion**

92 Special Applications of Photogrammetry

b)

The stability of the seven-story stone tower is evaluated by the results of photogrammetry

Fig. 19. Drawing results of stone tower: a) front, b) back (Sin & Kim, 2006; Yoon, 2006)

1. Extend and determine to vertical axis for center of the seven-story stone tower 2. Evaluate incline of the seven-story stone tower based on the determined vertical axis

analysis. The stability evaluation is as followed;

This chapter introduces research cases related to photogrammetry and a real-time measuring system (called as visual monitoring system, VMS) which is based on digital photogrammetry. It confirms the applicability of digital photogrammetry in civil engineering structures and cultural assets. The research conclusions are followed as;

Application of a Photogrammetric System for Monitoring Civil Engineering Structures 95

Han, J. G.; Hong, K. K.; Kwak, K. S. & Cho, S. D. (2005). Simulation Evaluation of Visual

Han, J. G.; Hong, K. K.; Kim, Y. S.; Cho, S. D. & Kwak, K. S. (2007). Development of

Han, J. G.; Jeong, Y. W.; Hong, K. K.; Cho, S. D.; Kim, Y. S. & Bae, S. H. (2006). Displacement

Han, J. G. & Song, Y. S. (2003). Displacement Measuring System for the Slope Stability

Hannah, M. J. (1989). A system for digital stereo image matching, *Photogrammatic Engineering and Remote Sensing*, Vol.55, No.12, pp. 1765-1770, ISSN 0099-1112 Kang, J. M.; Yoon, H. C. & Bae, S. H. (1995). A Study on the 3-D Deformation Analysis for

Kim, J. S.; Park, W. Y. & Hong, S. H. (2003). The 3D Modelling of Cultural Heritage Using

Kraus, K. (2007). *Photogrammetry: Geometry from images and laser scans*, Walter de Gruyter,

Lee, S. C.; Hwang E. J. & Han J. G. (2006). Efficient Image Retrieval Based on Minimal

Lichti, D. D. & Chapman, M. A. (1995). CCD camera calibration using the finite element

Munjy, R. A. H. (1986). Calibrating non-metric cameras using the finite-element method,

Ohnishi, Y.; Nishiyama, S.; Yano, T.; Matsuyama, H. & Amano, K. (2006). A study of the

*Society*, Vol.19, no.4, pp. 23-32, ISSN 1229-2427 (in Korean)

Kraus, K. (1993). *Photogrammetry*, Vol. 1, Dümmler Verlag, Bonn, Germany Kraus, K. (1997). *Photogrammetry*, Vol. 2, Dümmler Verlag, Bonn, Germany

ISBN 978-3-11-019007-6, Berlin, Germany

447-459, ISSN 1016-2364

USA, March 10-15, 1985

0099-1112

1609

Korean)

Korean)

Korean)

pp. 1-10, ISSN 1229-2427 (in Korean)

45-52, ISSN 1975-2423 (in Korean)

Monitoring System for The Dam Measuring, *Proceedings of KSCE 2005 Conference*, pp. 3982-3985, Jeju Special Self-Governing Province, Korea, October 20-21, 2005 (in

Automatic Displacement Measuring System using 3D Digital Photogrammetry Image and Its Application, *Journal of the Korean Geotechnical Society*, Vol.23, No.5,

Measuring Lab. Test of Reinforced-Soil Retaining Wall Block using 3D Digital Photogrammetry Image, *Journal of the Korean Geosynthetics Society*, Vol. 5, No. 3, pp.

Analysis Using the Softcopy Photogrammetry*, Journal of the Korean Geotechnical* 

Safety Diagnosis of Bridges, *Journal of the Korean Society of Surveying, Geodesy, Photogrammetry, and Cartography*, Vol.13, No.2, pp. 69-76, ISSN 1598-4850 (in

Digital Photogrammetry, *Journal of the Korean Society of Surveying, Geodesy, Photogrammetry, and Cartography*, Vol. 21, No. 4, pp. 365-371, ISSN 1598-4850 (in

Spatial Relationships, *Journal of Information Science and Engineering*, Vol.22, No.2, pp.

method, *Progress in Biomedical Optics and Imaging(Videometrics IV;SPIE Proceedings Series)*, No. 2598, pp. 34-43, ISSN 1605-7422, Philadelphia, USA, October, 1995 Munjy, R. A. H. (1985). A finite element analysis of the effect of having fiducial marks in

non-topographic photogrammetry, *Annual Meeting 51st*, pp. 160-169, Washington,

*Photogrammetric engineering and remote sensing*, Vol.52, No.8, pp. 1201-1206, ISSN

application of digital photogrammetry to slope monitoring systems, *International Journal of Rock Mechanics & Mining Sciences*, Vol.43, No.5, pp. 756-766, ISSN: 1365-


Digital photogrammetry is applied in various fields and it is developed rapidly with development of image processing techniqe and image acquisition apparatus. Therefore, if digital photogrammetry is applied continuously in civil engineering structures, micro measuring instruments, and cultural assets, it is a very useful tool as disaster prevention monitoring system due to the quantitative digital image. However, image acquisition apparatus should be improved in high precision. Techniques of camera capacity should be developed to decrease an error rate of image acquisition apparatus. With high techniques, real-time monitoring system will be used more widely in various fields.

#### **6. References**


1. In deformation measuring of welded members, the accuracy and applicability of VMS was verified by comparing the deformation values of VMS with those of the loading test instrument (MTS-810). It is seen that the developed VMS has the high precision

2. VMS is applied to displacement measuring of reinforced CMU retaining wall. The average difference of VMS is less than 3.6% in total test cases. This means that the measuring result was verified reasonably in all target points except the dropped target. 3. The accuracy of VMS based on simulated field test is satisfied in theoritical difference range. Therefore, the its applicability was verified reasonably in civil engineering

4. It introduces the applicability of digital photogrammetry in maintenance and restoration of cultural assets. The result confirmed that the stability of cultural assets is evaluated by digital photogrammetry. Also, it can be applied as maintenance technique.

Digital photogrammetry is applied in various fields and it is developed rapidly with development of image processing techniqe and image acquisition apparatus. Therefore, if digital photogrammetry is applied continuously in civil engineering structures, micro measuring instruments, and cultural assets, it is a very useful tool as disaster prevention monitoring system due to the quantitative digital image. However, image acquisition apparatus should be improved in high precision. Techniques of camera capacity should be developed to decrease an error rate of image acquisition apparatus. With high techniques,

Bae, S. H. (2000). *The component development of digital photogrammetry for the construction* 

El-Hakim, S. F. & Wong, K. W. (1990). Working group V/1: digital and real-time close-range

Fraser, C. S. (1993). A resume of some industrial applications of photogrammetry, *ISPRS* 

Fraser, C. S. (1997). Full Automation of Sensor Calibration, Exterior Orientation and

Gruen A. (1992). Recent advances of photogrammetry in robot vision, *ISPRS Journal of Photogrammetry and Remote Sensing*, Vol. 47, No. 4, pp. 307-323, ISSN 0924-2716 Han, J. G.; Bae, S. H. & Oh, D. Y. (2001). Application of photogrammetry method to

Han, J. G.; Chang, K. H.; Jang, G. C.; Hong, K. K.; Cho, S. D.; Kim, Y. S.; Kim, J. M. & Shin, Y.

Proceedings, Vol. 1395, p. 2, Bellingham, Washington, USA, 1990

*Tech*, Vol.4, no.3, pp. 10-18, ISSN 1229-3032 (in Korean)

*structure displacement analysis*, Doctoral thesis, Chungnam national university,

photogrammetry, Close-Range Photogrammetry Meets Machine Vision, SPIE

*Journal of Photogrammetry and Remote Sensing*, Vol.48, No.3, pp. 12-23, ISSN 0924-

Triangulation in Industrial Vision Metrology, *International Workshop on Image analysis and information fusion*, pp. 13-24, ISBN 0646330691, Adelaide, Australia,

measurement ground-surface displacement on the slope, *J. Korean Env. Res & Reveg.* 

E. (2008). Development of a Visual Monitoring System for Deformation Measuring of Welded Members and Its Application, *Materials Science Forum*, Vols. 580-582, pp.

real-time monitoring system will be used more widely in various fields.

comparison with test results using MTS-810.

structure

**6. References** 

2716

Korea (in Korean)

November, 1997

557-560, ISSN 1662-9752


**5** 

**Photogrammetry for** 

Rami AL-Ruzouq

*Jordan* 

*Al-Balqa' Applied University* 

**Archaeological Documentation** 

**and Cultural Heritage Conservation** 

Photogrammetry is the art and science of deriving accurate 3-D metric and descriptive object information from multiple analogue and digital images. Recently, there has been an increasing interest in utilizing imagery in different fields such as archaeology, architecture, mechanical inspection, and surgery. Photogrammetry is concerned with deriving measurements of the size, shape, position and texture of objects from measurements made on photographs. In its simplest form, a pair of overlapping photographs is used to create a three-dimensional model, with the use of appropriate instrumentation can yield quantifiable dimensions of the object. Traditionally, these dimensions were represented on maps and plans, either as elevations, facades and/or contours. The use of photogrammetry as a tool to aid in the documentation of cultural heritage has a long history, and is well established as a measurement science. Recent advances in the science make the techniques much more flexible in their application and present new opportunities in the representation of monuments as diverse as aboriginal rock painting shelters, historically significant buildings

The archaeological heritage constitutes the basic record of past human activities. Its protection and proper management is therefore essential to enable archaeologists and other scholars to study and interpret it for the benefit of present and future generations. In this chapter, Geomatics techniques will be used for archaeological documentation of one of the most important sites in Jordan (Aqaba Fort). The city of Aqaba, Jordan is located along the northern shore of the Gulf Aqaba with a central coordinate of 29.5° N 35.0° E . The port in Aqaba provides the country of Jordan with their only marine site for the import and export of goods. It is also considered as one of the most popular tourist resort in Jordan and the Middle East where warm climate, beaches, and coral reefs. Aqaba is connected to the urban centres of Jordan to the north by two highway. There are overland border points to Eilat (5 km north) and Saudi Arabia (16 km south), and ferries connecting Jordan directly to Egypt.

The 'Aqaba' is short of the old Arabic naming Aqaba Ayla, meaning 'Pass of Ayla'.

GIS will be used to create vector layers of the main architecture component of the fort. Photogrammetry will be employed to generate a digital elevation model and an Orthophoto which can be used together to give an actual terrain view for the historical structure

and structures, and culturally significant precincts or districts.

**1. Introduction** 


http://www.ejge.com/2001/Ppr0118/Abs0118.htm

Yoon, S. B. (2006), *(A) Study on the Analysis and Restoration of Cultural Assets With Digital Photogrammetry*, Master's thesis, Sangju university, Korea (in Korean)
