1135 
ASSESSMENT OF ALOS PRISM DIGITAL ELEVATION MODEL EXTRACTION 
OVERJAPAN 
F. Bignone a , H. Umakawa b 
a INFOTERRA France, EADS China, 6th Sanlintun XiLiuJie, Beijing, P.R. of China - frank.bignone@infoterra.ff 
b PASCO, Fligashiyama, Meguro-ku, Tokyo 153-0043, Japan-(hiroko_umakawa)@pasco.co.jp 
KEY WORDS: Photogrammetry, Remote Sensing, Cartography, Correlation, Production, Digital 
ABSTRACT: 
This article presents technical work done with DAICHI ALOS PRISM data in order to assess the feasibility and quality of Digital 
Elevation Model extracted from ALOS PRISM triplet of images. Thanks to its configuration, the PRISM instrument is capable of 
simultaneous stereoscopic acquisition of the observed landscape which should easier the automatic processing of such data for 
Digital Elevation Model extraction. By analyzing ALOS data available over an area in Japan, with other reference information, this 
article will present both the current possibilities available with PRISM data and their limitations. 
1. INTRODUCTION 
Remote sensing and earth observation satellites are nowadays 
used in a broad range of applications: mapping, resource 
management, simulation, risk and disaster management, and 
recently on online geo-applications such as GoogleEarth or 
equivalent. A good example of the healthy situation of this 
spatial industry can be derived by the successful launch of 
many earth observation satellites during the last two years, and 
upcoming launch on new satellites, such as WorldView-1, 
DAICHI, CBERS, TERRASAR-X, KOMPSAT-2, THEOS, 
PLEIADES and so on. 
Considering the specific case of DAICHI (Advanced Land 
Observing Satellite: ALOS) satellite, it has been successfully 
launched on the 24 th of January 2006 by the H-IIA #8 at 
Yoshinobu Launch Complex located in JAXA's Tanegashima 
Space Centre, Japan. The objectives of the ALOS are mainly 
cartography in small scale, regional observation for "sustainable 
development", disaster monitoring, and resources surveying, 
around the world. To realize them, ALOS took sun synchronous 
sub recurrent orbit, and the platform comprises of three 
different instruments: two optical sensors (AVNIR and PRISM) 
and one SAR sensor (PALSAR). AVNIR instrument is mainly 
designed for multispectral optical data collection for land 
observation. PALSAR instrument, L-band Synthetic Aperture 
Radar, is aimed for day-and-night and all-weather land 
observation. PRISM panchromatic instrument has been 
designed mainly for mapping purpose with a specific aim 
towards Digital Elevation Model extraction. Indeed, PRISM is 
capable of simultaneous stereoscopic acquisition of the 
observed landscape which should easier the automatic 
processing of such data for Digital Elevation Model extraction. 
However few studies have already been done concerning the 
qualitative validation of PRISM (Tadono T. and all, 2004) 
stereoscopic acquisition with respect to Digital Elevation Model 
extraction. One reason may be the recent commercial 
availability of PRISM data along with geometric information 
provided as RPC models. Another reason may be the short list 
of available digital processing solution which can generate high 
quality Digital Elevation Model from PRISM stereoscopic 
acquisition. 
Concerning Digital Elevation Model extraction and automatic 
processing of stereoscopic images, a full range of different 
methods are available and have been already published such as 
automatic window-based correlation, least-square matching- 
based correlation, feature-based matching and so on. However, 
few of these techniques have been fully implemented into an 
operational production tool which can be used on large dataset. 
In order to take as much benefit of a large coverage of 
simultaneous stereoscopic acquisition as possible, automated 
production tools should be used in order to remove burden of 
manual processing and easier management of large dataset. 
Indeed, an integrated and automated system for Digital 
Elevation Model processing will take the most benefit of ALOS 
PRISM data collection. As a matter of fact, the proposed 
analysis of this article will be conducted by using one of such 
digital software package which offers an extensive automated 
framework to process digital aerial and satellite data. Moreover, 
results will present a qualitative analysis of PRISM Digital 
Elevation Model compared with reference data on the same area. 
2. ALOS PRISM INSTRUMENT 
As introduced previously, the PRISM instrument (JAXA, 2007) 
is capable of simultaneous stereoscopic acquisition of the 
observed landscape thanks to its three panchromatic cameras 
with a resolution of 2.5 meters at nadir angle. Each camera 
consists of several CCD detectors to achieve a large number of 
detectors per line (14.000 for the backward / forward cameras 
and 28.000 for the nadir camera). 
Geometric information about the ALOS platform is available in 
addition to RAW images in order to rigorously model the 
sensor geometry and to achieve high accuracy measurements 
from these instruments.