AN INTEGRATED APPROACH FOR TOPOGRAPHICAL MAPPING FROM SPACE 
USING CARTOSAT-1 AND CARTOSAT-2 IMAGERY 
Amitabh*, B. Gopala Krishna, T P Srinivasan and P K Srivastava 
Space Applications Centre, Indian Space Research Organisation, Ahmedabad -380 015 (ISRO), India - 
(amitabh, bgk, tps, pradeep)@sac.isro.gov.in 
Commission IV, WG IV/9 
KEY WORDS: Cartosat, Mapping, Application, Digital Elevation Model, Accuracy, Feature 
ABSTRACT: 
Topographical mapping constitutes an integral component of the process of managing land resources, and mapped information is the 
common product of analysis of remotely sensed data. High resolution space-bome remote sensing image data show a high level of 
detail and provide opportunities to be integrated into mapping applications. For mapping, the geometric potential and also the 
information content in the satellite images are important. Today Cartosat-1 provides the along track stereoscopic coverage at 2.5 m 
resolution globally while Cartosat-2 acquires images at less than 1 m which is comparable to any of the globally available high 
resolution satellites. Topographic maps are designed to be a multi-purpose base maps and typically depict a variety of map features 
on the landscape on a particular scale. A topographic map contains terrain, forest, vegetation, roads, lakes, buildings, and geographic 
names. From Cartosat-1 data, terrain (DEM) can be extracted while the achieved accuracy of the DEM is depending upon the pixel 
size, the base to height relation, the contrast and slope of the area, but also the time interval between imaging both scenes. On these 
parameters of accuracy Cartosat-1 fits perfectly. The other information content (viz- forest, vegetation, roads, lakes and buildings) 
have been extracted by Cartosat-1 stereo images (3-D feature extraction) and further can be supplemented by Cartosat-2 (2-D feature 
extraction). DEM generated from Cartosat-1 data is being used for ortho-rectification of Cartosat-2 data. Older maps, City/district 
maps and Mobile mapping system (Palmtop & hand held GPS) are the other sources to collect the geographic names. There is a 
tremendous reduction in the ground truth data collection (field verification) by using Cartosat-1 and Cartosat-2 datasets together. 
The accuracy and morphologic information contents in both the satellites are sufficient for most of the mapping application.This 
paper describes a methodology to generate/update 1:25000 topographical map using Cartosat-1 and Cartosat-2 images in an 
integrated approach. This approach include data pre-processing, modeling of space imagery, DEM and Ortho-image generation with 
or without GCPs, accuracy improvement of DEM and Ortho-image, Image to Image registration, 2D and 3D feature extraction and 
mapping in a standard cartographic environment. This study also provides a guideline for the 2D or 3D extraction for different 
feature types. 
1.0 INTRODUCTION 
Digital mapping constitutes an integral component of the 
process of managing land resources, and mapped information is 
the common product of analysis of remotely sensed data. High 
resolution space-bome remote sensing image data show a high 
level of detail and provide opportunities to be integrated into 
mapping applications. For mapping, the geometric potential and 
also the information content in the satellite images are 
important. The demand for accurate and up-to-date spatial 
information is increasing and its availability is becoming more 
important for a variety of tasks. Today’s commercial high- 
resolution satellite imagery (HRSI) offers the potential to 
extract useful and accurate spatial information for a wide 
variety of mapping and GIS applications. The extraction of 
metric information from images is possible due to suitable 
sensor orientation models, which describe the relationship 
between two-dimensional image coordinates and three 
dimensional object points. 
ISRO remote sensing program provides a constellation of polar 
satellites at various resolutions to map the globe. Cartosat-1 and 
Cartosat-2 are the two ISRO satellites used for cartography. 
Cartosat-1 was launched on May 2005 with two cameras fore 
and aft. Cartosat-1 provides the along track stereoscopic 
coverage at 2.5 m resolution globally. One of the most 
significant application of Cartosat-1 is to generate digital 
elevation models (DEMs). A DEM is a discrete expression of 
topography in a data array, consisting of a group of planimetrie 
coordinates (X,Y) and the elevations (Z) of the ground points 
and the breaklines. Cartosat-2 is another satellite of ISRO 
having a single panchromatic camera which acquires images at 
very high resolution (less than 1 m) which is comparable to any 
of the globally available high resolution satellites. This satellite 
was launched in January 2007 by PSLV. With the advent of 
image processing and remote sensing systems, the use of 
imagery for collecting geographic features has become more 
frequent. This imagery included: radiometric corrected imagery, 
geometric corrected imagery and ortho-rectified imagery. Each 
type of imagery has its advantages and disadvantages, although 
each is designed to the collection of geographic information in 
2D and 3D [1]. 
The typical digital mapping project requires DEM generation, 
Contour interpolation, Ortho-image generation and Feature 
extraction. Topographic maps are designed to be a multi 
purpose base maps and typically depict a variety of map 
features on the landscape on a particular scale. A topographic 
Corresponding author 
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