Narayan, L.R.A. 
1.2 GIS Usage 
Use of GIS picked up very fast not only in the case of natural resources, but also for various business and 
commercial applications and gave a big thrust into the area of Facility management. The Cartographic data 
bases needed in all cases were drawn from the existing topographic maps on 1:50,000, published by the Survey 
of India. The Survey of India, the national mapping agency has a record of over two and half centuries and has 
to its credit a complete coverage of 1:50,000 scale topographic maps, with a contour interval of 20 meters, 
matching International specifications and standards. India is covered by over 5000 sheets on 1:50,000 scale and 
is also mapped on 1:250,000 scale by compilation from 1:50,000 sheets. Recently, Indian mapping effort has 
also extended to map at a scale of 1:25,000 scale, in selected regions and perhaps in the coming years, a 
complete coverage may result, particularly where development possibilities are visualized. Being a large country 
with nearly 3.5 million sq.kms in area, to keep these maps up to date is not a very easy task and needs 
considerable resources. 
1.3 
As a result complete coverage of base maps on 1:50,000 scale being available and as a result of complete 
coverage of IRS 1C & 1D satellite data, including higher resolution PAN data, and 24 meter resolution MSS data, 
merging of these have been found very useful particularly when these are Geo-Coded to fit in within the frame 
work and boundaries of the 1:50,000 scale topographical base maps, already available, to evaluate and analysis 
of various natural resources and monitoring changes as and when required. This possibility and availability of a 
variety of GIS packages have resulted in integration of several types of data including socio-economic data for 
very effective planning in the case of several development projects, including its usage as a decision support 
systems. 
2. SHORTCOMINGS AND DIFFICULTIES 
2.1 
In spite of all above mentioned advantages, there has been several difficulties and problems that have been 
encountered, which has resulted in the large non utilization of remote sensed data as well as finding effective 
solutions through GIS usage, as most essential condition in GIS is availability freely accurate cartographic data 
bases. Unfortunately all 1:50,000 scale or 1:25,000 scale topographical maps are not freely available to all users, 
particularly the private enterprises, except those which fall in the non-restricted zone. Secondly for large scale 
data bases, where it is required essentially, such as in the case of urban management, small water shed 
development mostly needed for improved agricultural practices, is not available with close contours. There has 
not been an organized effort to produce them either, as a result, people try to enlarge existing 1:50,000 or 
1:25,000 scale topo sheets, which carries with it large inherent positional errors. Beside these, digitizing the 
official topographical maps on 1:50,000 scale is authorized to only about 8 or 9 organizations, which again is a 
great disadvantage. While everyone understands the power of remote sensing and GIS, many have wrong 
notions on using positionally accurate cartographic data bases for accurate GIS development and consequent 
reliable usage as an effective planning mechanism, for a variety of developmental projects. 
2.2 AERIAL PHOTOGRAPHY 
It is well known that aerial photographs as an accepted data to develop positionally accurate maps on various 
scales and this capacity is available in India since a longtime with official agencies, authorized to do so. Since 
recently there are some private enterprises come forward to establish infrastructure in the from of analytical 
photogrammetry systems and developed operating capacity at a very high level, mainly to meet the work offers 
coming from outside India. Some of these companies have established such high level of expertise that many 
users outside India has recognized them capable of meeting world standards, and as the prices for such an 
activity in India is comparatively cheaper due to cheep labor availability. However, the Indian authorities have 
not recognized this fact and still restrict the availability of aerial photographs covering any part of India for 
mapping by such private agencies, except in very exceptional cases, under strict surveillance by officially 
authorized agencies. In addition the producers and suppliers of satellite data have not realized what all goes into 
producing accurate cartographic or topographic maps, within the national mapping framework. Consequently 
with these constraints, the accuracy of GIS at detailed level has suffered seriously, which many users have not 
well understood. The complementary usage of satellite remote sensed data and Aerial Photographic data is not 
still well understood, as one cannot replace or match the other. How far the recent IKNOS satellite data of 1 
International Archives of Photogrammetry and Remote Sensing. Vol. XXXIII, Part B7. Amsterdam 2000. 963