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SFAP for highway feasibility study
Prof. P. Misra
Consultant, Land Information Technologies,
J-94, South Extension – Part One
New Delhi - 110049.
Tel: (011) 462 3106
Conventional aerial photography (format 23cm
x 23cm) has been practised in India for the last
60 years or more. There are three agencies in India which carry out aerial photography, namely, National Remote Sensing Agency (NRSA), Hyderabad, Air Survey Company, Calcutta and the Indian Air Force. The traditional format is quite all right if the project area is large and mapping is the main objective.
Of late, however, a number of requirements of land information pertaining to small areas like jhuggi-jhompri (JJ) clusters, unauthorised construction etc have become predominant, specially, for the urban administrators and planners. The information which is almost techno-legal in nature is required in a short time. It is very useful for taking strip photography of a highway corridor. The project authorities cannot wait to commission large agencies because the lead-time for an aircraft to come, for instance, from Hyderabad to Delhi is undesirably high. This also becomes too costly in case the area is insignificantly small say a jhuggi cluster covering an area of ½ km x ½ km. Prof. Misra in collaboration with Prof Juppenlatz of ITC, Netherlands introduced of the SFAP technology in India. The Rohini Project of DDA, Chandigarh and Haridwar were photographed using Small Format Aerial Photography.
The liberalisation policy in India has provided a big fillip to the highway and transportation sector which deservedly gets the top priority amongst infrastructure related projects. Getting proper physical information for planning the highway related projects still remains a major bottleneck and causes major delays. This is primarily due to the utilisation of the traditional surveying technology of field-oriented surveys. In a specific case, the cost of marking the centre line of proposed alignment, cross sections and preparation of acquisition plan is quoted to about Rs.20, 000 + per kilometer. Small Format Aerial Photography (SFAP) is a proven technology through which, it is visualized to reduce the cost to more than 50% of the conventional method. SFAP is not only cost-effective, it is also highly time-effective, technically accurate and verified in office.To get an idea on the national scale i.e. for highways of 40,000 km, the saving to the national exchequer is likely to the extent of (30,000 x 10,000) 30 crore.
Small Format Aerial Photography
In SFAP, a simple method of taking aerial photography has been designed. Instead of large and conventional format of 23cms x 23cms, an ordinary/commercial camera of 35mm or preferably 70mm format is used. The film is also ordinary film (black & white or colour) which is readily available in the market.
The camera is taken aboard a single engine, small aircraft of low cruising speed (also helicopter). The photographer uses the camera in a hand-held mode. In some cases, a simple modification is done in the aircraft by creating a hole and the camera is fitted in a suitable mount. The photography is done with 60% overlap so as to provide a three-dimensional view of the terrain.
All aerial photography including SFAP is governed by Aircraft Rules. Defence Security clearance is necessary before any flying can be undertaken in India. In case all procedures/requests are according to the rules, the security clearance takes from 1½ month to 2 months. Even after the aerial photography is done under the supervision of the security officer, the exposed film is subjected to the security checks.
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