EVALUATION OF CARTOGRAPHIC ACCURACY OF THEMATIC MAPPER DATA

Abstract

Advent of Remote Sensing techniques through selective spectral sensors on board the artificial satellites have made available enormous data to the scientists, for mapping, updating and monitoring of natural resources on global basis. Since the launch of first earth resource satellite in 1972, there has been tremendous advancement in sensor/scanner technology. Spectral as well as spatial resolution of the sensors have been gradually improved to a great extent. Many experiments have been conducted to evaluate the cartographic potentials and the geometric fidelity of satellite imagery. In this dissertation, investigations have been carried out to evaluate the cartographic potential of thematic mapper data products by various methods. Conformal, affine as well as polynomial transformation techniques are utilised to convert image coordinate system into ground coordinate system. Analysis of the investigation for a full TM scene by conformal transformation method, using machine coordinates, indicate a mean positional error (m.p.e.) of 451 m for 49 GCP's and 360 m for 147 check points. When the same TM scene is analysed by dividing it into four strips, then a m.p.e. of around 130 m for GCP's and 110 m for check points is obtained. Results of the investigations for TM Quadrant - 1, utilising digital coordinates and different transformation techniques are 1 encouraging. A m.p.e. of 146 m, 36 m and 14 m for GCP's and 194 m, 46 m and 37 m for check points, is obtained by conformal, affine and polynomial transformation respectively. From these results it have been concluded that the cartographic potential of thematic mapper imaging data is justifiable for thematic maps on 1:100,000 scale and smaller. Improvement in the positional accuracy by affine transformation techniques, indicate the differential tendency of TM imaging system. Visual and digital analysis of the TM scene have confirmed its suitability for resource surveys. It is an economical tool for quick updating, monitoring and mapping of regional resources, for the developing countries.