Technology
In India, topographical maps are the best source of Geographic data required for variety of purposes. Today public has access to these topographical maps in a limited way and on a very selective basis. This is due to restriction policy of the Government, which traces its origin to British days.
Geographic data in digital mode should be generated by one agency and be made available centrally.
NRSA should use GCPs observed by GPS based on WGS84 Spheroid to make their data internationally compatible to various softwares available in the market
The policy of depriving public access to Indian Geographic Data has been a subject of discussions in many forums. A number of resolutions have been passed by the professional bodies at the end of their seminars, workshops and meetings. Many Committees have worked on it. But so far not much has been done in the current situation when there have been lot of technological developments in generating alternate sources of data. This piecemeal approach is not at all appropriate for such an important subject. What is needed is an honest effort to study the subject in its totality, taking into account various issues and find the right solution.
Issues and Ground Realities
Survey of India and National Remote Sensing Agency (NRSA) are the two principal agencies generating geographic data in the country. Survey of India produces topographical maps based on ground surveys with input from aerial photography. National Remote Sensing Agency produces satellite data, currently of 5.8 metre resolution. Aerial photography, another source of Indian geographic data and a restricted document is produced by Indian Airforce and NRSA on need based. There have been number of issues, mentioned below are required to be studied in depth:
- Indian Geographic Data is based on Everest Spheroid and all ground observations are linked to its geometry.
- Planimetric control data upto one minute of arc and heights above mean sea level rounded off to 10 metres in restricted zone is made available to the public against payment.
- Heights upto 0.1 metre are published on unrestricted topographical maps
- Survey of India maps carry copy right legend
- All topographical maps in restricted and unrestricted zone, before they are published, undergo security vetting by Ministry of Defence. Maps containing international boundary are also sent to Ministry of External Affairs for clearance of the boundary line.
- There is no standard list of Vital Areas (VAs)/Vital Places (VPs) available for open circulation to the public. These are maintained separately by Ministry of Defence and Ministry of Home Affairs.
- Indian Remote Sensing Satellites are using Ground Control Points (GCPs) supplied by Survey of India. The geometry of satellite data generated by these Satellites is therefore linked to Everest Spheroid.
- All satellite data is to be cleared by Ministry of Defence before it is made available to the general public. Certain areas containing VAs/VPs in the satellite data are masked at present.
- Digital geographic data in unrestricted zone is restricted.
- In addition to Survey of India, the following 8 Government Departments/Agencies have been allowed to undertake digitization of topo maps of unrestricted areas upto 1:50,000 scale already published by Survey of India from which Defence/Civil VAs/VPs and important strategic locations have already been deleted.
- Department of Space
- National Informatics Centre
- Ministry of Rural Areas and Em ployment
- Geological Survey of India
- National Bureau of Soil Survey and Land Use Planning
- Ministry of Water Resources
- Ministry of Environment & Forest
- Department of Ocean Development
- In addition to various other conditions, these organizations can digitize the unrestricted maps limited to the certain information as mentioned in Table - 1.
- Today GIS has application in every range of land related activities from governance to business. GIS Industry is therefore growing in the country and demand for Indian geographic data both in map form and digital mode is on the increase to carry out projects for their clients
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