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> Fundamental 
Kazuo Oda 
  
DSM BASED ORIENTATION TECHNIQUE FOR DIGITAL STEREO PHOTO IMAGES 
Kazuo ODA”, Takeshi DOIHARA”, Osamu UCHIDA”, Ryosuke SHIBASAKI““ 
*Asia Air Survey Co., Ltd., Japan 
kz.odaQ ajiko.co.jp, ta.doihara  ajiko.co.jp, os.uchida 9 ajiko.co.jp 
ods of 
Ed 
“Center for Spatial Information Science, University of Tokyo, Japan 
shiba@ jun.iis.u-tokyo.ac.jp 
Working Group IV/2 
.KEY WORDS: Orientation, Photogrammetry, DEM, DSM 
ABSTRACT 
Digital Surface Model Based Orientation Technique is a new method for stereo image orientation based on image regis- 
tration technique. The basic idea is that this orientation technique optimizes orientation parameters ( ;X. V, Z) of 
each image of a stereo pair so as to give best image matching at each point on a digital surface model. This method does 
not require ground control points (GCP) but uses digital surface model instead. Experimental test resulted that the preci- 
sion of orientation is better than the resolution of DSM. 
1. INTRODUCTION 
Aerial photo is one of the most important spacial data sources because of its reality and abundance of geographical infor- 
mation. However, users often encounter difficulties in utilization of them, since in most cases orientation parameters of 
photos are not available and users have to effort to find relationship between photos and other geographic or computer 
graphic object by themselves. To provide solution for such kind of needs, we have studied orientation method with exist- 
ing geographic data such as digital maps and digital surface models (Doihara et.al.(1999)). 
Here we propose a digital surface model (DSM) based orientation technique, which can calculate absolute orientation 
parameters automatically with DSM available. DSM based orientation goes ordinary photogrammetric process reversely. 
DSM based orientation conducts optimization of orientation parameters with existing DSM, whereas, in photogramme- 
try, operator first calculates orientation parameters for pairs of images and then calculate or measure surface model by 
triangulation. This method uses DSM instead of ground control points for orientation process. 
Image registration technique is one of the important backbone of DSM based orientation. The most important difference 
from existing registration technique, such as Szeliski et.al (1994) or Oda (1998), is that our registration is performed on 
orthoimages: the algorithm optimizes orientation parameters which create approximately the same orthoimages from ste- 
reo pair images. 
This paper first describes the theory of DSM based orientation, including basic strategy and implementation in least 
square method. After that we show some results of tests with this theory to show the performance and precision of this 
technique. 
2. THEORY OF DSM BASED ORIENTATION 
2.1 Basic Strategy 
The basic idea of this method is to solve image registration problem under the condition that the position of objects in the 
stereo scene is known. With assumption of some proper initial value of absolute orientation parameters, image coordi- 
nates pI and p2 on the stereo images / ; and /, can be calculated for points on DSM. If the absolute orientation param- 
eters are closer to the correct value, the difference between pixel values at pI and p2 should become smaller. DSM 
based orientation calculates the parameters which give a least squares solution of the following evaluation function 
= 1, pl -1, p2 ' (1) 
  
International Archives of Photogrammetry and Remote Sensing. Vol.. XXXIII, Part B3. Amsterdam 2000. 651