The International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences. Vol. XXXVII. Part Bl. Beijing 2008 
1181 
RMSE X = 2.7 m 
RMSE y = 3.9 m 
RMSÉ h = 2.8 m 
4. DISCUSSION AND CONCLUSIONS 
ALOS-PRISM allows for a positional accuracy and density of 
information well compatible with mapping scale 1:25,000. The 
methodology proposed in this paper is capable of doing an 
image orientation nearly as good as what is achieved with 
standard GCPs. The main advantage is to avoid any field work 
for GCP collection. However the method still has to be tested 
with images of different areas, in different types of terrain in 
order to be completely validated. 
The method was applied to images of mode 1B2-R, which are 
not in original sensor geometry. This may limit the potential 
positional accuracy of ALOS-PRISM. Anyway the principle of 
orientation with a reference DEM surface can also be applied to 
images of modes 1A or 1B1, in original sensor geometry. In 
that case a rigorous sensor model would be used, doing 
adjustments in actual exterior orientation parameters, such as 
the sensor attitude angles. 
A limitation that can be pointed to this methodology of 
matching elevation data is that it does not work in flat areas. 
However it still works in areas with relatively small mean 
slopes, such as 5%. 
References from Journals: 
Gonsalves, J., Mar9al, A., 2007. Automatic Ortho-rectification 
of ASTER Images by Matching Digital Elevation Models, 
Springer Lecture Notes in Computer Science, No. 4633, 1265- 
1275. 
Grodecki J and Dial, G., 2003. Block Adjustment of High- 
Resolution Satellite Images Described by Rational Polynomials. 
Photogrammetric Engineering & Remote Sensing, Vol. 69, No. 
1, January 2003, pp. 59 - 68. 
Toutin, T., 2006. Generation of DSMs from SPOT-5 in-track 
HRS and across-track HRG stereo data using 
spatiotriangulation and autocalibration. ISPRS Journal of 
Photogrammetry and Remote Sensing, Volume 60, Issue 3, 
Pages 170-181 
Toutin T. and Cheng P., 2001. DEM generation with ASTER 
stereo data. Earth Observation Magazine, 10, pp. 10-13 
Gonçalves, J., 2006, Orientation of SPOT stereopairs by means 
of matching a relative DEM and the SRTM-DEM. Proceedings 
of the International Calibration and Orientation Workshop - 
EuroCOW2006, Barcelona, 2006 (CD-ROM). 
Gruen, A., Kocaman, S., Wolff, K., 2007. Geometric Validation 
of ALOS/PRISM Images. Proceedings of the First PI 
Symposium of ALOS Data Nodes, Kyoto, Nov., 2007 (CD- 
ROM). 
Rodriguez, E., C.S. Morris, J.E. Belz, E.C. Chapin, J.M. 
Martin,W. Daffer, S. Hensley, 2006. An Assessment of the 
SRTM Topographic Products. JPL Report. 
Spotimage, 2004. SPOT 123-4-5 Geometry Handbook. 
Document reference GAEL-P135-DOC-OOL 
Saunier, S., Goryl, P., Bouvet, M., Santer, R., Chander, G., 
Gruen, A., Viallefont, F., 2007. The contribution of the 
European Space Agency to the ALOS PRISM / AVNIR-2 
commissioning phase. Proceedings of the First PI Symposium 
of ALOS Data Nodes, Kyoto, Nov., 2007 (CD-ROM). 
Takaku, J., Futamura, N., Iijima, T., Tadono, T., Shimada, M., 
Shibasaki, R., 2005. High resolution DSM generation from 
ALOS PRISM data - Pre-launch Simulation and Assessment 
Plans. Proceedings IGARSS 2005, Seoul, IEEE, 2005. 
Takaku, J., Tadono, T., 2007.PRISM geometric validation and 
DSM generation status. Proceedings of the First PI Symposium 
of ALOS Data Nodes, Kyoto, Nov., 2007 (CD-ROM). 
ACKNOWLEDGEMENTS 
To the Japanese Space Agency (JAXA) and European Space 
Agency (ESA) for providing PRSIM images under ALOS 
ADEN proposal no. 3738. 
To the Portuguese Geographic Institute for providing the 
control DEM. 
SRTM data provided by NASA/NGA/USGS. 
References from Other Literature: 
Baudoin, A., M. Schroeder, C. Valorge, M. Bernard, V. 
Rudowski, 2004, The HRS-SAP initiative: A scientific 
assessment of the High Resolution Stereoscopic instrument on 
board of SPOT 5 by ISPRS investigators. ISPRS Congress 
Istanbul 2004. 
Fraser, C., Rottensteiner, F., Weser, T., Willneff, J., 2007. A 
New Generic Sensor Orientation Model Applied to Alos 
Imagery. Proceedings of the First PI Symposium of ALOS Data 
Nodes, Kyoto, Nov., 2007 (CD-ROM).