GCP Acquisition for the Geometric Correction of IRS-1C/D Imagery: Requirements and Issues in India
S. K. Katiyar
Sr. Lecturer
Civil Engg. Department
M.A.N.I.T., Bhopal-462 007
Tel. No. 0755-2670593
Email: skatiyar7@rediffmail.com
Onkar Dikshit
Associate Professor
Civil Engg. Department
I. I. T. Kanpur- 208 016
Tel. No. 0512-597937
Email: onkar@iitk.ac.in
Krishna Kumar
Director
M.N.N.I.T. Allahabad
Tel. No. 0532-2540233
Email: kkumar@mnnit.ac.in
Abstract
Satellite images are vital tool in various applications like land use and land cover mapping, Geographic Information System (GIS) etc. Remotely sensed images are often considered as maps of the radiometric properties of the earth’s surface. However, these are not usually map-like. A variety of factors involved in the process of image acquisition, introduce geometric distortions, which are removed by the process of geometric correction. As technology progresses, the raster picture element (pixel) resolution of digitally acquired remotely sensed imagery continue to become finer in spatial resolution. This dictates the need of ground control points (GCPs) with increased spatial accuracy to geometrically correct remotely sensed data from high resolution satellites like SPOT, IRS-1C/D and IKONOS.
Conventionally GCPs are derived from maps, but in the developing countries most of the existing maps and medium scale maps are out of date due to large population growth, rapid changes in urban areas and economic development. Global Positioning System (GPS) has emerged as a very powerful tool for the acquisition of ground control points (GCPs) with the desired accuracy. In India full potential of GPS technology could not be utilized by the civilian users for the mapping requirements in Indian datum, due to restriction policies of the Government of India. This research paper presents investigations on the geometric correction accuracy of IRS-1C/D LISS-III and PAN sensor imagery using 1:50,000 and 1:25,000 scale SOI map derived and GPS derived GCP coordinates. Limitations of map derived GCPs and problems in the transformation of GPS coordinates into Indian datum are also investigated.