The role of satellite derived maps in National Spatial Data Infrastructure

PVSP.Prasada Raju Sujata Ghosh and J. Saibaba
ADRIN, Dept.of.Space, Govt.of.India
203, Akbar Road, Tarbund Secunderabad-500 009


Introduction
In the context of significant developments in the field of remote sensing, especially in terms of spatial and spectral resolutions, enhanced the scope of remote sensing and GIS applications during late nineties significantly. At the same time, advancements in the digital photogrammetric and cartographic techniques facilitate the user a variety of tools for data integration, conversion and manipulation into flexible, efficient and precise spatial databases. Unfortunately, the details provided in the maps by various Organizations like Survey of India (SOI), National Atlas and Thematic Maps Organization (NATMO), Geological survey of India (GSI) and others were not coped with the information content offered by finer resolution imagery such as IKONOS, Quick bird etc., and it was resulted in the void between data availability and its utility at the appropriate mapping scales. Hence, it is appropriate on the part of the National Spatial Data Infrastructure (NSDI) to utilize the multi-resolution and multi-spectral data offered by various remotely sensed satellites (Indian Remote Sensing series and other). The data provided by various satellites will have to cater the requirements of decision makers at various scales from regional to micro (village) level.

In fact, the Dept.of.Space has carried out many remote-sensing application projects at the country, regional and local scales using multi-resolution imagery. These projects proved the capability of satellite-imagery in natural resources mapping. The spatial database (proposed) available with the NSDI has to cater the user data requirements at least three levels, namely, national, regional and local scales and further, it has to serve a wide range of applications through a centralized database to various government organizations, public undertakings and non-governmental organizations. Data in the form of small-scale maps already available with many organizations like the Survey of India, Geological Survey of India, National Atlas and Thematic Map organization etc. The Survey of India (SOI), premier institute has been preparing and supplying topographic maps for the country on 1:250,000, 1:50,000 and 1:25,000 scales and moreover many of these maps were few decades old. In the context of NSDI, it is pertinent here to describe the capability of remote sensing technology visa-vis mapping requirements and availability of maps in the country. Now it is possible to generate the thematic maps on various scales ranging from 1:2500 and 1:10,00,000 scales keeping in view the end users requirement. The locational accuracy of maps is utmost important for certain applications like Cadastral survey, infrastructure/ utility maps and Urban land use/ planning etc. Using one-meter resolution imagery and GPS controls, it is now possible to achieve an accuracy of +/- 2 meters. It will be appropriate here to discuss the technical lag between the large-scale topographic maps on 1:25,000 scale published by SOI and the utilization of information provided by finer resolution (around 1 meter) offered by recently launched satellites. The utility of remotely sensed derived information/maps, especially from finer resolution satellites was described in the context of National Spatial Data Infrastructure. In order to study the application and mapping potential of very high resolution data like IKONOS, Cartosat etc., the Dept.of. Space, Govt.of.India has recently carried out some pilot projects on Large Scale Mapping under Remote Sensing Application Mission (RSAM). The pilot studies demonstrated the mapping potential of the finer resolution imagery. Advanced Data Processing Research Institute (ADRIN) and National remotes Sensing Agency (NRSA) were carried out two pilot studies on Large scale mapping using IKONOS (1 Mt) data and these studies suggesting that an accuracy of 6 mts and 2 mts locational accuracy taking controls from 1:25,000 scale SOI map and GPS based points respectively. These studies also proved that one could go up to 1:2500 scale thematic mapping such as urban land use. Issues related to mapping requirements of users, available maps and their scales, standards, satellites derived mapping products etc., were discussed herewith.

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