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Geodesy in India: From Triangulation to GPS

Madhav N. Kulkarni
Department of Civil Engineering
Indian Institute of Technology, Bombay, India

Over the centuries, along with the numerous political upheavals that the country witnessed, sciences and technology also developed significantly, often with the blessings of the royal armies, leading to several note-worthy discoveries and inventions. The Geodetic sciences formed an integral part of this progress, with spectacular achievements in the fields of astronomy, positioning, mathematics, cartography, and map-making. From the well-documented progress in Geodetic Astronomy, and the surveys for preparing the ancient maps of the country and of the regions over which the great kings ruled, to the precise positioning of points for the great monuments like Qutub Minar, Char Minar, Taj Mahal, and the several ancient cities, forts and magnificent royal palaces, the science of Geodesy progressed gradually through the centuries. Great Indian astronomers, geodesists and mathematicians like Aryabhatta, Bhaskaracharya, Brahmagupta, and others, contributed significantly to the surveying and mapping sciences, through their note-worthy discoveries.

Over last two centuries, the ancient science of classical geodesy slowly gave rise to the modern geodesy. With the British Raj came the modern technologies, and the need for geodetic surveys spanning over the entire country. A significant step in this transformation was the establishment of Survey of India (SOI), India’s premier geodetic surveying and mapping agency, in 1767. Started as a modest part of the Royal Engineers, this first technical department of Government of India soon became one of the leading surveying and mapping organizations in the world. The challenging task of carrying out geodetic surveys for mapping one of the largest nations, with diverse terrains, from the snowy peaks of Himalayas to the Gangetic plains, and from the dense rainforests of North-East India to the vast deserts of Rajasthan, was completed by the dedicated geodesists and surveyors of SOI over the years.

The list of the great geodesists and surveyors of India, who contributed to the growth of modern geodesy, includes such legendary figures like Sir (Colonel) George Everest, Colonel Lambton, Brigadier Bomford, and numerous other unnamed Indian surveyors. The completion of the Great Trigonometrical (GT) Triangulation Survey of India, with over 3000 high precision geodetic stations spanning across the sub-continent, was made possible by the dedicated efforts of these surveyors. Precise determination of the height of the highest peak in the world: Mount Everest, based upon this network, is one of the most celebrated achievements of modern geodesy. It is a well-known fact that the peak was named in 1856 after Sir George Everest, a British military engineer who served as Surveyor General of India from 1829 to 1843, during which time the peak was surveyed: a be-fitting tribute to one of the greatest geodesists of all time. Colonel Everest, rightly called the “father of Indian Geodesy”, was the first person to record the location and height of the mountain, then known as Peak XV.

In the field of Geodetic Gravimetry also, India can proudly claim the contribution of many important developments, including the theory of isostacy. It is a tribute to the foresight of such great geodesists that at today the country has an extensive geodetic survey network built on scientific principles. The geodetic survey control net works of India, including the GT Triangulation, high precision leveling, Laplace stations, gravimetric stations, geomagnetic stations, tidal stations, and the more recent Doppler survey stations and Global Positioning System (GPS) stations, established over two centuries of dedicated work, form one of the most extensive and precise geodetic networks in the world. These networks also form the foundation of the precise mapping of the entire country.

Traditionally, the geodetic surveying operations for precise positioning of points on the surface of the Earth for the purpose of mapping the region were very complex, laborious and time-consuming processes. The geodetic aspects of mapping: the determination of the precise positions of few prominent features or survey points in the area, called “control points”, for providing geometric properties- the scale of the map, involved detailed ground survey. The positioning, or provision of “control points”, which controlled the geometric properties and the scale of the map, was carried out using ground measurements of lengths and angles, using theodolites and chains/tapes, which were later replaced by Electronic Distance Measuring instruments (EDMs). Both these terrestrial methods demanded extensive field work, involving large manpower, expenditure, efforts and time; thus making the geodetic surveying and mapping process slow and tedious. In order to ensure inter-visibility between survey stations, often towers: either permanent brick towers (especially in the Gangetic plains) or assembled steel Bilby towers (last used by the author in West Bengal in early 1980s), were constructed. Most national surveying and mapping organizations in the world, including Survey of India, had to put in several decades of labour-extensive work, to complete the geodetic surveys and the topographical mapping of the country, using these classical techniques.

The positioning input to mapping: the provision of precise coordinates of few control points in the area, for mapping purpose, continued to be provided by ground-based methods, till the introduction of the space geodetic techniques in the 1970s. The first space-based positioning system: the TRANSIT Navy Navigation Satellite System (NNSS), the satellite navigation system launched in 1958 by the U.S. Navy and made available to the international users in 1967, was used in India to augment the geodetic control, and to connect the islands to the mainland, in the 1970s and 80s. Indigenous “Doppler surveying receivers” were also designed and fabricated by the Space Application Centre, Ahmedabad. Other space geodetic systems, like Satellite Laser Ranging (SLR), Lunar Laser Ranging (LLR), Very Long Baseline Interferometry (VLBI), etc., though operational since 1960s world-wide, did not play a significant role in the geodetic activities in India directly, mainly due to their very high cost, though efforts were made in the 1990s to establish SLR and VLBI facilities in India.

For geodetic surveying, the GPS, with its economy, low cost, versatility, and ease of operation, has become the most preferred positioning method within few years of its launch. The introduction of GPS has truly revolutionized the field of modern surveying and mapping in India, over the last two decades. From precision positioning to mapping, commercial applications to scientific studies, small scale maps to large scale maps, navigational and positioning applications, including navigation on land, in air and on sea, determining the precise coordinates of important geographical features as an essential input to mapping and Geographical Information System (GIS), precise cadastral surveys, vehicle guidance in cities and on highways using GPS-GIS integrated systems, earthquake and landslide monitoring, surveying, geodetic control networks, crustal and structural deformation studies etc., GPS is today being used for a wide spectrum of applications in India, by various organizations.

In India, significant developments have taken place in the fields of GPS over the last two decades. For everyday surveying, GPS has become a highly competitive technique to the terrestrial surveying methods using conventional techniques, whereas in geodetic fields, GPS has almost replaced most techniques currently in use for determining precise horizontal positions of points more than few tens of km apart. The three main aspects of the modern GPS technology: the instrumentation, the software and the manpower, have developed significantly in India over this period. The rapidly expanding use of computer technology in India has been a great boon for GPS. Most organizations in India today are increasingly using GPS technology for the effective utilization of their resources.

Many scientific government organizations, including Survey of India, Indian Institute of Geomagnetism, Mumbai, National Geophysical Research Institute, Hyderabad, National Informatic Centre, Wadia Institute of Himalayan Geology, Dehradun, Centre for Mathematical Modelling & Computer Simulation, Bangalore, National Remote Sensing Agency, and many educational Institutes and Universities like Indian Institutes of Technology, Anna University, Chennai, Indian Institute of Remote Sensing, Dehradun, etc. are involved in GPS-related activities for various applications. Many ambitious programmes related to different applications of GPS, have been launched, including the National GPS Programmes for Earthquake Studies by Dept. of Science & Technology, (see:, and Dept. of Space, Govt. of India, the Differential GPS network by Dept. of Light Houses, Govt. of India, GPS-based aviation programme: GPS Aided Geostationary Aviation System (GAGAN), GPS use by Defence Forces, etc. Many other non-government scientific, educational and commercial organisations have also procured GPS equipments for different applications, including crustal movement studies for earthquake monitoring, National Highways project, City guide maps, GIS, etc.

On the hardware and software front, even though some indigenously manufactured GPS instrumentation is available, its technical and economical viability needs vast improvement. As a result, most of the GPS hardware in use today is imported. In GPS-related software development, the contribution of Indian geodesists is expanding, and efforts are on to develop indigenous software systems, like GRAM++ of IIT Bombay, for the Indian and global markets, even though we have a long way to go in this field. The problems posed by the selective availability, the anti-spoofing and transformation of the GPS coordinates from WGS 84 to the Indian datum are being investigated, in order to ensure an economic, efficient and effective implementation of GPS technology in India. The need for establishing a national GPS centre to co-ordinate the activities of the various organizations in this field and to explore the feasibility of establishing a GPS tracking stations network in India to obtain precise positioning of the satellites is being felt increasingly.

In manpower development also, many academic and professional organizations, both in Government and private sectors in India, are offering comprehensive training courses related to GPS. However, introduction of GPS as a major field of study in educational institutes and Universities has not yet materialized, and more efforts are required in this direction. With the ever-expanding use of the GIS and GPS technologies, and the numerous programmes launched in these fields, the need of trained manpower to implement these programmes is self-evident. On the academic front, there are some Universities/ Academic Institutes in India which offer regular academic courses in these areas. At the undergraduate level, GIS-GPS related subjects are mostly included as part of Surveying / Geodesy / Mapping courses, in the Civil Engineering or Geography specializations. Even though the feasibility and demand for a basic degree in GIS-GPS is still being debated, the demand for these specializations as the Master’s degree level is well-established. The seven Indian Institutes of Technology (IIT’s), and many Engineering colleges and Institutes have been offering GIS-GPS related courses as part of their Bachelor of Technology / Engineering (B.Tech. / B.E.) programmes in Civil Engineering, over the last several years, with some of them also offering these specializations at Master’s level. Some Institutes, like the Survey Training Institute of SOI, cater to the training needs of their parent department. However, the increasing demand of trained manpower in these fields requires significant augmentation of these academic resources.

With the significant developments in Geodesy in India over last few centuries, and the rapid progress made in adopting the modern geodetic technologies, the geodetic and GPS-related activities in India are poised for a quantum jump in the near future. The globally-acclaimed Information Technology (IT) revolution in the country, the large pool of computer-trained young engineers and scientists and the recent developments in the fields of electronic instrumentation and software development, are important factors, due to which the GPS-Geodesy fields are witnessing note-worthy progress. It is expected that in the near future, the digital geodetic surveying technologies will not only change the way the developmental projects are planned, implemented and executed, but also will truly revolutionize the concept of mapping in the country.

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