> detected by 
ve conflicting 
f orthophotos. 
> enhancement 
actical way for 
1g commercial 
optimal for all 
'ious user may 
a tone-model- 
:nted. 
1990. The Use 
for Merging 
Image Data. 
ng, 56(4), pp. 
ster Graphics 
10ld Company 
t Practise and 
Commission, 
stitute for the 
1g Agriculture 
ssue 2:3. 
Or ortho 
> 
Huttunen, A., 
ps. Reports of 
usministerión 
tujáürjestelmá. 
Jigital image 
s and Curves. 
orial page 1. 
. The use of 
'  Landsat-5 
d Mapping. 
ig, 66(7), pp. 
and Methods 
ress. 
ition between 
_td., National 
yment Centre 
are gratefully 
. Istanbul 2004 
FAST GEOREFERENCING IMAGES 
THROUTH GENERALIZED PHOTOGR AMMETRIC ALGORITHMS 
Chao-Hong Liu 
Department of Computer Science and Information Engineering, National Dong Hwa University, 
1, Sec. 2, Da Hsueh Rd., Shou-Feng, Hualien, Taiwan - chliu@gnu.org 
Working Group V6 
KEY WORDS: Photogrammetry, Algorithms, Georeferencing, Image, Three-dimensional, Geometry, Triangulation 
ABSTRACT: 
Traditional photogrammeric workstations for georeferencing images are usually time- and human resource-consuming, input data 
source specific, and lack of flexibility to use in a generalized triangulation problem. These characteristics have made them inadequate 
to be used in case of emergency. The approach presented in this paper started after Chi-Chi Earthquake of Richter Magnitude 7.3 
struck central Taiwan on September 11th, 1999, in response to the situation that we did not have a proper tool to deal as soon and 
easy 
even a few 
totally based on 
hexagonal approach to pattern matching is also provided in this paper to reduce t 
extraction. 
1. INTRODUCTION 
The approach presented in this paper is a direct response to the 
need in the survey of surface rupture of Chelungpu Fault 
invoked by Chi-Chi Earthquake of Richter Magnitude 7.3 struck 
central Taiwan on September 1 1th, 1999 (Liu et al, 2000). The 
situation encountered is that the Earth surface had been changed, 
and acceptable data of what it was is still not available even a 
few months later. This resulted in the use of the older and 
incorrect maps for almost half a year by the in situ disaster relief, 
geological surveying, civil engineering, and reconstruction teams. 
It is a critical problem since the terrain had been drastically 
changed in some areas, and the decision maker had no idea where 
the urgent resources should be placed. Although several 
techniques have been tried to derive the displacement data of 
surface rupture after the quake, the use of aerial photos through 
photogrammetry seems to be the last and the only one 
applicable technique. This paper presents how to fast 
georeference images taken by any source, such as aerial photos 
and  surveyors field photos, through a generalized 
photogrammetric algorithm to ease the situation by providing 
acceptable geographic information of a vast area in few days. 
The design principles of the algorithms are 1) independent of 
specific input data sources, 2) relevant to geometry, 3) built-in 
with three-dimensional architecture, and 4) no default 
automation will be executed or ignored if ambiguous conditions 
are encountered, in which a black box like proprietary software 
as possible with the problem that the Earth surface had been changed, and acceptable data of what it was is still not available 
months later. In respondingthe need ofa proper tool to deal with, generalized photogrammetic algorithms are developed 
geometry to reduce the computing overheads needed to calculate space resection and relative orientation. A 
he intensive time spent in the process of feature 
generally could not provide. To make sure each calculation is 
explicitly defined by primitive mathematical equations from the 
bases, a concise fundamental spatial library and a 
photogrammetric package for the algorithm, both written in Java 
and available as Free Software under GNU General Public 
License version 2, are developed. The algorithms could be 
regarded as generalized triangulation methods since they are 
designed and programmed totally based on geometry, and are 
used to derive the displacement data of surface rupture of 
Chelungpu Fault. In order to make them more powerful and 
efficient in practical uses, the development of the software will 
be gradually migrated into ANSI C/C++, will the Java version 
still be usable and under maintenance, however. 
A hexagonal pattern recognition algorithm is also presented in 
this paper. The preliminary version of this algorithm was first 
written in ArcView/Avenue and AML, and as the Avenue 
scripting language is no longer under maintenance, these codes 
are planned to re-program in Java and GRASS in their next 
versions. 
2. GENERALIZED ALGORITHMS 
Since the major applications of photogrammetry lie on aerial 
usage, most workstations are designed and well developed for 
this specific application. This unfortunately makes them 
inadequate to be used in a generalized photogrammetric problem, 
and forces MIT City Scanning Project to develop their own