719 
DETERMINATION OF DISPLACEMENTS IN LOAD TESTS WITH DIGITAL 
MULTIMEDIA PHOTOGRAMMETRY 
F. Yilmazturk 3 , S. Kulur 3 , N. Terzi b 
3 ITU, Civil Engineering Faculty, 80626 Maslak Istanbul, Turkey - (yilmazturk, kulur)@itu.edu.tr 
b AU, Faculty of Engineering, Aksaray, Turkey - niyaziterzi@gmail.com 
Commission V 
KEY WORDS: Photogrammetry, Close Range, Expert System, On-line, Video, Software 
ABSTRACT: 
This paper describes the use of multimedia photogrammetry for determine of deflection behavior of buried flexible pipe 312 mm 
diameter is placed in highly strengthened steel box under load. 20 mm thick transparent Plexiglas was used in front face of the box. 
An on-line configuration of three CCD cameras was established to measure targets subject to positional displacement. The entire 
measurement process was consist of five steps: calibration of camera system, acquisition of multi-image sets, establishment of 
corresponding points in the images, computation of their 3-D coordinates, acquisition of images after each load application and 
computation of 3-D coordinates. The algorithm proposed by Maas (1995) was used in order to solve problems of multimedia 
photogrammetry. For this algorithm is used, the XY plane of coordinate system should be chosen parallel with the plane interface 
air/glass. Sub-millimeter object point precision has been achieved in all three coordinate dimensions for each measurement epochs. 
1. INTRODUCTION 
The testing and monitoring of structures and structural 
components under different loading conditions are a standard 
engineering application. Geometrical measurements are 
performed for the examination of the behavior of test objects 
and for the verification of theories or mechanical models. This 
is often realized by static, quasi-static, or dynamic short and 
long time load experiments on test objects. In these tests, it is 
demanded to determine parameters and effects such as the 
changes in shape, load and strain which are commonly 
measured by LVDTs, extensometers and strain gauges. These 
devices provide on-line results with a high geometric precision 
and reliability. A general disadvantage of these techniques, 
however, is their point wise and only one-dimensional 
measurement capability. The techniques are generally not suited 
for tasks requiring a large number of measurement points 
distributed over an object surface or for complete surface 
measurements. In these cases, techniques of digital 
photogrammetry depict a valuable option for the design of 
powerful and flexible measurement tools (Maas, 2006; Hampel, 
2003; Whiteman, 2002; Woodhose, 1999 ). 
However, while the measurement of the absolute coordinates 
and the movement of signalized targets on an object can be 
solved by commercial software packages, non standard 
monitoring tasks or multimedia photogrammetry applications 
will often necessitate the development of customized software 
tools. 
In this study, the photogrammetric system has been developed 
to measure the coordinates of signalized targets on structural 
components during static load tests and to solve problems of 
multimedia photogrammetry. Three experiments are carried out 
in order to demonstrate the functionality of the system. Vertical 
loads were applied with the increments of 10 kPa up to 140 kPa 
using air pressure membranes. Digital photogrammetric system 
has been used together with the classical measurement device 
LVDT in load tests and the measurement results were compared 
with each other. 
At first, the design of the photogrammetric measurement system 
is described. Then, the measurement process and the algorithm 
used to solve problems of multimedia photogrammetry are 
given. Finally, results of the measurement are summarized. 
2. SYSTEM CALIBRATION 
The three progressive scan CCD cameras (Basler a302fc ) with 
a resolution of 780x582 pixels was used in developed system. 
The two cameras were fitted with 16 mm lenses, whereas the 
other camera had a minimum focal length of 12 mm and a 
maximum focal length of 70 mm. The CCD cameras were 
connected to the PC by the IEEE-1394 port (also called 
FireWire or i-link). Some features of the cameras can be 
controlled by software through the IEEE-1394 port. 
The multiple camera system was oriented and calibrated by 
bundle calibration method and for these purposes a test field 
with white targets on a black background whose coordinates in 
space were known was used (Figure 1). The results of the 
calibration process are the exterior orientation of the cameras 
(position and rotations), parameters of the interior orientation of 
the cameras (camera constant, principle point), parameters for 
the radial and decentering distortion of the lenses and optic 
systems and two additional parameters modeling differential 
scaling and shearing effects. A thorough determination of these 
parameters modeling distortions and other effects is required to 
achieve high accuracy in the measurement (D’appuzo, 2003). 
After the calibration and orientation of cameras was determined, 
before loads were applied, the signalized target points on object 
must have labeled in images. For this purpose, at first the 
images of test object was scanned for a specific template image 
and image coordinates of the recognized target images were