Geodesy in India: From Triangulation to GPS

INTRODUCTION OF SPACE GEODETIC 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.

DEVELOPMENTS IN GPS FIELD
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: http://www.civil.iitb.ac.in/~kulkarni/DSTBroFinal.pdf), 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.

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