Proposed methodology for georeferencing and mosaicking Corona photographs

Abstract

A practically based user‐friendly methodology to accurately georeference and colour balance Corona photographs for large area coverages without compromising information content by downgrading their high spatial resolution is presented. Tapping on a range of techniques provided in the Erdas Imagine environment, the procedures laid out in this paper go a step further than normal software guidelines by providing improvised techniques that are graphically illustrated by reference to a study area (the Okavango Delta in northern Botswana) covering about 65 000 km² to allow the reader to assimilate the sequence of steps involved. With self evident usable results in the form of a 2 m‐resolution seamless mosaic providing blanket coverage for the above stated area on 15 September 1967, it is apparent that similar initiatives elsewhere can take advantage of our proposed methodology in putting together what is retrievable from the archives by building databases that extend time horizons into the historical past for use in long‐term environmental monitoring.

Acknowledgments

The authors wish to thank the Southern Africa Science Regional Initiative (SAFARI 2000), Canon Collins Educational Trust for Southern Africa (CCETSA) and START International for co‐funding ongoing research work that enabled us to compile this paper. We are extremely grateful to Kelley Caylor of the University of Virginia for facilitating the acquisition of Corona photographs. Special thanks go to Raban Chanda for his comments and suggestions, and Botswana's Department of Surveys and Mapping for scanning our negatives.