Byung-Uk Park 
  
HOUGH TRANSFORM FOR INTERIOR ORIENTATION IN DIGITAL 
PHOTOGRAMMETRY 
Sohn, Hong-Gyoo, Yun, Kong-Hyun 
Yonsei University, Korea 
Department of Civil Engineering 
sohnl Q yonsei.ac.kr 
ykh1207 Q yonsei.ac.kr 
Yu, Kiyun 
Deputy Director Team for National GIS 
Ministry of Construction and Transportation, Korea 
kiyun Q motc.go.kr 
Jeong, Soo 
Yonsei University Engineering Research Center, Korea 
jeong@ yonsei.ac.kr 
Working Group III/3 
KEY WORDS: Hough Transform, Local Dynamic Thresholding, Digital Photogrammetry, Interior Orientation 
ABSTRACT 
It is known that Hough transform is insensitive to noise and the desired results can be acquired even in the damaged 
image. Because of its applicability to the image with variations such as rotations or scale changes, Hough transform has 
been widely used to detect the outlines of arbitrary-oriented and arbitrary-scaled objects such as straight lines or circles, 
In this paper, we utilized Hough transform combined with the local dynamic thresholding method to accurately locate 
the center location of fiducial marks. Using detected fidual marks and calibration data, it was possible to determine the 
calibration coefficients to do interior orientation. 
1 INTRODUCTION 
Automatically locating the outline of arbitrary objects from digital image has been studied in digital 
photogrammetry, pattern recognition and other disciplines. Extracting linear features or boundary of the objects is 
primary task to perform higher level analysis of the input image. Hough transform has been widely used to identify 
image features such as straight or curved lines (Ballard, 1981). It has also been applied to the variety of pattem 
recognition of arbitrary oriented and shaped objects (Tzvi and Sandler, 1990; Xu et al.1990). 
Many parameters and steps are included to calculate the 3-D coordinates of the object from two stereo image pairs. 
As the first step of 3-D formation of the object, we perform the interior orientation to accurately establish the 
relationship between pixel image coordinate system and image coordinate system. There are many interior orientation 
parameters to be considered. They include atmosphere refraction, camera imperfections, film shrinkage, and scanner 
error. Important element of interior orientation is to identify the central location of fiducial marks from input digital 
image. In this paper, we utilized Hough transform combined with local dynamic thresholding method to automatically 
determine the central location of fiducial marks. Using the detected fiducial marks and calibration data of fiducial marks, 
the parameters from pixel coordinate system to photo coordinate system using affine transformation are determined. 
2 ALGORITHM OF HOUGH TRANSFORM 
Hough transform was first proposed by Hough (Hough, 1962). An example to detect straight lines using this method 
was presented by Duda and Hart (1972). When many distributed points that seem to be in the straight line, the original 
line can be traced along these points via Hough transform. 
One pixel in image space is represented as one straight line in parameter space. Many pixels that are supposed to be 
straight line in parameter space are mapped many lines in image space. Crossing point of these lines in parameter space 
is detected as one straight line segment in the image space. 
  
692 International Archives of Photogrammetry and Remote Sensing. Vol. XXXIII, Part B3. Amsterdam 2000. 
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