An Integrated Rural Mapping using
Remote Sensing and GPS Techniques
Dr. Satyaprakash and Dr. R. Sivakumar
GIS Institute
CSDMS, G-4, Sector-39, Noida
Abstract
Of late, GPS has been increasingly recognized as one of the best surveying technology. It has found numerous applications in surveying for sub-centimeter level accuracy like, from crustal deformation and missile launching to coarse surveying for sub-meter accuracy such as geological mapping and locating fishes. The measurement from GPS is used in getting locations for GIS projects and also for the spatial distributions of GCPs (Ground Control Points) for georeferencing in digital image processing of satellite images and for high-resolution image analysis. This paper discusses, the use of GPS and its integration with high-resolution images for different kinds of surveying/mapping, with emphasis on its use with low cost mapping in the rural sector. The paper takes up a case study of a village in Faridabad.
Introduction
Rural mapping is as old in India as is the culture of revenue collection or “Lagaan” collection. Even before that, people used to have record of their lands, both in the form of maps and in the tabular form, for ownership purposes. Shershah Suri, an eminent ruler first gave a methodical shape to the land record survey system, in north India, for a better way of collecting his land revenues. The British continued to operate with the same system of land records for land revenue collection. However, for the government, it is not only the land revenue collection that is important but also the development of villages. For proper development, government needs various critical information (spatial and non-spatial) in the form of maps of the villages, agricultural area, socio economic data, the settlements that are scarcely available, etc. Different surveying techniques have been used in the past for mapping the land of the villages. Each technique has its own merits and demerits, and it has been often rightly found that not one technique is able to give a complete solution to the problem of mapping the villages. With the advent of space based technologies, like GPS, Remote Sensing and Aerial Photography, it has become easier for implementers to integrate the data collected through these technologies with a GIS (Geographic Information System) for better governance.
Different Surveying for Rural Mapping
Different surveying techniques are being used and have previously been used for rural mapping. It has been found that none of them suffice the need of modern technology. The most commonly used can be listed below.
Traditional
Traditional survey includes the measurement of distances by tape, stadia, angles by compass, mapping by plane table survey, leveling by autolevel, angle measurement by theodolite, distance measurement by EDM (Electronic Distance measurement) and the most recent one TS (Total Station), which is a combination of theodolite and EDM. But surveys by these traditional methods are labour intensive and time consuming. With time, there has been a need of integrating these data and maps to the GIS, which is again time consuming and labour intensive.
Aerial Photography
This technique is relatively more accurate and quick. One can generate 1:4000 or even larger scale maps using a 1:20,000 photograph with modern digital photogrammetry techniques. However, due to security issues, in India, this technique is not that popular and not available to the common man. In spite of the restrictions, some areas have been mapped using Aerial photography and such photographs are available.
Satellite Remote Sensing
The recent advances in space technology have the potential of identifying the sub meters of an object on the ground. Hence in rural mapping the high-resolution images like IRS – PAN with the resolution of 5.8 meter is being used to identify the rural road network and update the boundary information. Similarly the launching of IKONOS data with the 1mt spatial resolution and 4mt multispectral data is widely used in mapping even a small hut in a village level. The analysis of the satellite data involves both, visual interpretation of image and digital image processing techniques. The accuracy point of view one can prepare map unto 1:5000 scale using Geoproducts of Ikonos. Several studies have been conducted on the aspects of accuracy due to integration with aerial photography and global positioning system. After pre-processing the raw data, the images are interpreted with image interpretation elements. But due to limitation in visually identifying the features it requires ‘digital image processing’ to enhance the interpretation capability through various processing techniques like image enhancement, filtering, band ratioing etc.,
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