INDIA'S entire geography has been covered by aerial photography, but development agencies and town planners cannot use the data because of national security regulations. "Even archival maps are not easily available to researchers," complains Majid Husain, head of the geography department at the Jamia Millia Islamia in New Delhi.

Participants at the conference of cartographers, those involved in the science of map-making, held recently in Delhi, criticised the monopolistic role played by the Survey of India saying the regulations controlling access to aerial photographs and baseline information make map-making difficult. The delegates urged private sector involvement in cartography should be increased to improve efficiency.

Advances in information technology have revolutionised cartography and Afzal Mohammad of the Centre for Economic and Social Studies in Hyderabad, explained, "We have entered a new phase. Paper maps are increasingly being replaced by electronic images and computer graphics."

Access to aerial photographs is restricted, but data and satellite imageries are easily accessible, though costly. The problem is that satellite imagery can at best provide maps with a scale of 1:50,000 and development planning often requires maps of greater accuracy and detail.