VALIDATION OF CARTOSAT-1 DTM GENERATION FOR THE SALON DE 
PROVENCE TEST SITE 
Marco Gianinetto 3 ’*, Francesco Fassi b 
3 Politecnico di Milano, Remote Sensing Laboratory, DIIAR Dept., Piazza Leonardo Da Vinci 32, 20133 Milano, Italy 
- marco.gianinetto@polimi. it 
b Politecnico di Milano, Elab3D Poli, DIIAR Dept., Piazza Leonardo Da Vinci 32, 20133 Milano, Italy - 
francesco.fassi@polimi. it 
Commission I, SS-11 
KEY WORDS: Satellite remote sensing, Digital elevation models, Space photogrammetry, Accuracy analysis, Topographic 
mapping 
ABSTRACT: 
Cartosat-1 is the eleventh satellite of the Indian Space Research Organisation series and is primarily meant for topographic mapping 
and Digital Terrain Model (DTM) generation. In the framework of the Cartosat-1 Scientific Assessment Programme, the Politecnico 
di Milano University (Italy) evaluated as Co-Investigator the performances of the Cartosat-1 satellite in the generation of DTMs. 
This paper describes the outcomes for the Salon de Provence test site (France) with respect to existing standards and products 
actually used in France and also provides a comparison with the global Shuttle Radar Topography Mission’s DTM supplied by 
NASA and widely used in the remote sensing community. 
1. INTRODUCTION 
The Indian Space Research Organisation (ISRO) launched the 
Cartosat-1 satellite on May 05, 2005. The satellite was 
primarily designed for topographic mapping and has two 
panchromatic Charge Coupled Device (CCD) sensors, both with 
a spatial resolution of 2.5m: i) the Fore camera, pointing +26 
degrees with respect to the nadir, and ii) the Aft camera, 
pointing -5 degrees with respect to the nadir. These sensors can 
either acquire along-track stereo images with a 27.5km swath 
and a base to height ratio (B/H) of 0.6 or mono images with a 
combined swath of 55km (Indian Space Research Organisation, 
2008). 
\ 
At the beginning of 2006 an agreement has been reached 
between the International Society for Photogrammetry and 
Remote Sensing (ISPRS) and ISRO to jointly conduct the 
Cartosat-1 Scientific Assessment Programme (C-SAP). The aim 
of the C-SAP was to assess the mapping capabilities of the 
Cartosat-1 satellite, especially with respect to the generation of 
Digital Terrain Models (DTMs) for different types of terrain. 
As Co-Investigator in the C-SAP, the Politecnico di Milano 
University (Italy) evaluated the performances of DTM 
generation from Cartosat-1 stereo data for the Salon de 
Provence (France) test site (C-SAP TS4). The investigation was 
carried on with respect to existing standards and products 
actually used in France (i.e., the French Institut Géographique 
National’s and Spot Image’s Reference 3D®, and the French 
®DB Alti). Moreover, the investigation also provided a 
comparison with the global Shuttle Radar Topography Mission 
(SRTM) DTM supplied by NASA and widely used in the 
remote sensing community. 
Imagery collected with Cartosat-1 were used for the generation 
of medium-resolution (25m grid cell size) and low-resolution 
(90m grid cell size) DTMs using commercial off-the-shelf 
software, so to provide comprehensive and operative hints to 
final users. 
2. DATASET 
2.1 C-SAP dataset composition 
The standard C-SAP TS4 dataset delivered to the investigating 
teams was composed of the following items: 
■ One 2.5m Cartsat-1 stereo pair collected over Salon 
de Provence (France) on February 6, 2006 
(Path=0128, Row=0198) and provided by ISRO; 
■ A set of 22 Ground Control Points (GCPs) provided 
by the Principal-Investigator (PI) French Institut 
Géographique National (IGN); 
■ One 19m x 26m resolution reference DTM 
(MNT DBTOPO® DTM) with IGN69 datum for 
heights, provided by the PI. 
In addition to the standard C-SAP TS4 dataset, it was also used 
a raster SRTM DTM made available from NASA (National 
Aeronautics and Space Administration, 2008). 
2.2 Standard accuracy of Cartsat-1 images 
ISRO delivered to the investigating teams Cartosat-1 imagery 
as Stereo Orthokit product in the GeoTIFF format (Figure 1) 
and also supplied predetermined Rational Polynomial 
Coefficients (Indian Space Research Organisation, 2005). The 
GeoTIFF Orthokit product is radiometrically corrected and is 
supplied to produce high precision cartographic products and 
DTMs: its location accuracy is better than 250m (3cr=220m for 
* Corresponding author. 
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