Generation of Digital Elevation Model derived from JERS1 SAR Interferometry 
Mitsuharu TOKUNAGA 
Institute of Industrial Science, University of Tokyo 
7-22-1, Roppongi, Minatoku, Tokyo 106, Japan 
TEL:+81-3-3402-6231 ext.2564 
FAX: +81-3-3402-6231 
Email: toku@shunji.iis.u-tokyo.ac.jp 
ABSTRACT 
This paper presents the DTM accuracy derived from JERS-1 SAR Interferometry based on the branch cut method. 
The target area were selected FUJI and FUGEN mountain in the volcanic mountaions. The accuracy of the calculated 
DTM is that maximum error and R.M.S.E were 217m, and 27.7m respectively. The accuracy weren’t better than 
theoretical values, but it is regarded as the next factor. 
(1) satellite position and orientations (2) precision of geometric correction (3) phase unwrapping algorithm 
In this paper, the one of DTM accuracy derived from JERS-1 SAR Interferometry made clear. 
INTRODUCTION 
The high accuracy Digital Terrain Model (DTM) has 
been required for the wide field of geoinfomatics, 
monitoring for environment and GIS. The trend will 
become strong because the high resolution satellite data 
will be available right away. Now, some method of 
approach for DTM generation are proposed. For 
example, the stereo matching using optical data or 
synthetic aperture radar (SAR) data, SAR 
interferometry, laser profile and so on are there. 
Recently, many articles about Interferometry SAR 
(InSAR) has been published. Because the potentials of 
InSAR has been proved in many fields, as DTM 
generation, glacier analysis, the earth crust change. 
Especially, InSAR is provided the high accuracy DTM 
that couldn’t derived from the others remote sensing 
data. 
However, the majority report is to develop the 
algorithm and to be calculated the fringe data. Few 
report is evaluated the DTM. 
In this study, the comparison DTM derived from 
interferometry SAR with DTM made from topographic 
map was carried out in order to clear the accuracy. 
FUNDAMENTAL OF DTM GENERATION BY 
INTERFEROMETRY SAR 
The Figure 1 shows the geometry of Interferometry 
SAR. 
SAR 1 
where: 
B : Baseline between two SAR antenna. 
a : inclination angle of baseline 
0 : incident angle of radar 
R1,R2 : the length of slant range 
H : the height of Satellite 1 from surface of the earth 
h : the elevation value of target point 
The difference of the slant length of SAR 1 and SAR 2 
is approximated the next equation. 
R2- R\ = Bs\n(0-a) 
(1) 
Also, the relation of difference of phase and elevation 
value shows the nest equation. 
(f) = 4kBs\x\(6- a) I A. 
where: 
A.: the wave length of radar 
(2) 
Then, the elevation values are calculated by the 
Pl-1-1 
y&Mm 
JMm 
itw 
'fny-fK: