THREE DIMENSIONAL DATA EXTRACTION FROM RADIOGRAPHS 
D. Z. Seker a ,G. Birgin 3 , A.Goktepe b 
a ITU, Civil Engineering Faculty, 80626 Maslak Istanbul, Turkey - (seker, gbirgin)@itu.edu.tr 
b Selcuk University, Science Technical College-agoktepe@selcuk.edu.tr 
Commission V, WG-V-6 
KEY WORDS: Electrophotography, X-ray applications, X-ray measurements, three-dimensional displays 
ABSTRACT: 
The aim of the study is to produce three dimensional (3D) data from radiographs using photogrammetric techniques. 
Photogrammetry is defined as the process of measurement on an object’s images taken in accordance with certain rules instead of 
direct measurements on the object. This term includes whole operations of taking, processing, analyzing and evaluating the image. 
Most important advantage of this method in medical studies is the high accuracy and cost effectiveness compared to classical 
methods. Thus, this study is a photogrammetric approach to medical research and applications. 
1. INTRODUCTION 
For performing measurements on three dimensional models, 
stereo X-Ray photogrammetry is a distinct approach. X-Ray 
photogrammetry is based on central projection of X-Rays that 
come from the focal point and fall on the film after passing 
through the object. X-Ray techniques are commonly used in 
medical sciences and industry. It is enables us to get physical 
data from the human body or a live object and to produce three 
dimensional images by using this data. By the help of this 
imaging technique; tumor, cancer, other abnormal activities, 
harmful unknown pieces like metal pieces in the stomach or 
other metal pieces as a result of injuries and positional changes 
and changes in the lengths of broken bones can be accurately 
measured. For Stereo X-Ray photogrammetry two X-Ray 
images with 50% or more overlap is required. Than these 
images are observed in stereo and in order to regenerate the 
object optically and mathematically, measurements are made on 
points taken from different positions on the object (Ege et al., 
2004; Malian and Heuvel, 2004; Everine et al, 2005). 
There are a few mathematical models used in X-Ray 
photogrammetry. Main aim of these models is to determine the 
positions of object points in a coordinates system. These 
operations are done with basic geometrical correlations and 
calibrations. Main mathematical models used in applications of 
X-Ray photogrammetry are the Seattle, Cleveland and Direct 
Linear Transformation (DLT) Model (Toz, 1987; Goktepe, 
2004). 
This study was conducted to incorporate photogrammetric 
approach into medical sciences, where analyze and modeling of 
bones were selected. The radiographs of forehand bones (ulna 
and radius) have been taken using X-ray technology. During 
this process, bones were nested into a specially designed and 
produced mold in order to establish the relationship between 
image and the object. Then, the radiographs have been scanned 
and digitized. Three dimensional object coordinates were 
obtained from picture (pixel) coordinates by means of DLT 
method. With these object coordinates, the digital three 
dimensional model of the bone was produced. The coordinates 
of the control points, which were located on the mold, have 
been recalculated by means of DLT method and then compared 
with the model coordinates. Points and their locations have 
been calculated and the 3-Dimensional model accuracy was 
checked. The final product is a 3-Dimensional model, where 
accurate measurements can be performed, visually 
understandable and easily interpretable. 
2. METHODOLOGY & RESULTS 
A three dimensional mold was designed. The mold is a form of 
box, which is made of plastic and a wood cover to protect the 
system. The designed mold is establishing the reference system 
and a coordinate base. The coordinate system surrounds the arm 
bones (ulna and radius) and 63 points with known coordinates 
are marked on the mold. 33 of these points have been 
positioned at the lower base, which is forming a grid. The 
remaining points were positioned asymmetrically on the right 
and left sides of the lower base, which is like a ladder structure, 
illustrated in Figure 1 and Figure 2. Thus, a three dimensional 
coordinate system was formed to surround the arm bones . 
Ergonomy of the human arm is also considered while designing 
the model. Thus, an ergonomic external box was designed to 
put the arm during the measurement process which also 
contains coordinates and prevents harms (Birgin, 2007). 
Figure 1. The Developed System