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GEOMETRIC POTENTIAL OF CARTOSAT-1 STEREO IMAGERY
M. Crespi* 0 , F. Fratarcangeli*, F. Giannone*, G. Colosimo*, F.Pieralice*, K. Jacobsen** 00
* DITS - Area di Geodesia e Geomatica - Sapienza Université di Roma- via Eudossiana 18 - Rome, Italy -
<mattia.crespi,francesca.fratarcangeli,ffancesca.giannone>@uniromal.it
** Institute of Photogrammetry and Geoinformation
Leibniz University Hannover
jacobsen@ipi.uni-hannover.de
0 Principal Investigator for ISPRS-ISRO C-SAP TS-6 and additional TS-Castelgandolfo
00 Co-Investigator for ISPRS-ISRO C-SAP TS-5 and TS-9
Comission I, SS-11
KEY WORDS: Photogrammetry, Digital, Geometry, Calibration, Block, Accuracy
ABSTRACT:
Cartosat-1 satellite, launched by Department of Space (DOS), Government of India, is dedicated to stereo viewing for large scale
mapping and terrain modelling applications. This stereo capability fills the limited capacity of very high resolution satellites for
three-dimensional point determination and enables the generation of detailed digital elevation models (DEMs) not having gaps in
mountainous regions like for example the SRTM height model.The Cartosat-1 sensor offers a resolution of 2.5m GSD in
panchromatic mode. One CCD-line sensor camera is looking with a nadir angle of 26° in forward direction, the other 5° aft along the
track. The Institute “Area di Geodesia e Geomatica” - Sapienza Università di Roma and the Institute of Photogrammetry and
Geoinformation, Leibniz University Hannover participated at the ISPRS-ISRO Cartosat-1 Scientific Assessment Programme (C-
SAP), in order to investigate the generation of Digital Surface Models (DSMs) from Cartosat-1 stereo scenes. The aim of this work
concerns the orientation of Cartosat-1 stereo pairs, using the given RPCs improved by control points and the definition of an
innovative model based on geometric reconstruction, that is used also for the RPC extraction utilizing a terrain independent
approach. These models are implemented in the scientific software (SISAR- Software per Immagini Satellitari ad Alta Risoluzione)
developed at Sapienza Università di Roma. In this paper the SISAR model is applied to different stereo pairs (Castelgandolfo and
Rome) and to point out the effectiveness of the new model, SISAR results are compared with the corresponding ones obtained by the
software OrthoEngine 10.0 (PCI Geomatica).By the University of Hannover a similar general satellite orientation program has been
developed and the good results, achieved by bias corrected sensor oriented RPCs, for the test fields Mausanne (France) and Warsaw
(Poland) have been described.For some images, digital height models have been generated by automatic image matching with least
squares method, analysed in relation to given reference height models. For the comparison with the reference DEMs the horizontal
fit of the height models to each other has been checked by adjustment.
1. INTRODUCTION
Cartosat-1, also named IRS-P5, provides along track stereo
imagery based on 2 cameras, having a view direction of 26°
forward and 5° backward, leading to stereo models with just
53sec time difference in imaging. The camera configuration
corresponds to a height to base relation (H/B) of 1.44 if the
curvature of the orbit is respected. The 12000 pixels, each with
7x7 microns, in the image plane are covering with the focal
length of 1.98m a swath of 30km with the forward view and
26.6km with the backward view. The GSD for a scene not
rotated around the orbit direction is 2.5m x 2.78m respectively
2.22m x 2.23m. The incidence angle of 97.87° together with the
flying height of 618km leads to a sun-synchronous orbit with
10:30 h equator crossing time in descending orbit. Cartosat-1 is
equipped with a GPS receiver for the positioning and star
sensors and gyros for the attitude determination. The satellite
can be rolled around the orbit to image the requested area (Fig.
1).
Fig 1. imaging configuration of Cartosat-1
