ADVANCED & ACHIEVEMENTS IN GEODESY IN THE SPACE AGE, WHICH INCLUDES THE RECENT TECHNIQUES OF PHOTOGRAMMETRY TOO

Abstract

Geodesy is that science which deals with the finding of the size and shape of earth in conjunction with other earth sciences. Its practical function is to perform the measurements and computations that will give the coordinates of selected control points on the earth's surface i.e. to fix the positions of the points on the earth's surface. There are several methods for doing this job, chief of them are triangu-lation, astronomical methods etc. and the recent method is the trilateration. When long distances are measured, earth's sphericity is taken in the calculation of triangulation nets and again for finding the earth's size and shape the one best, method is the triangulation. So both are interdependent and one is a prerequisite for the other. Old limitations and capabilities in the process of triangulation and other methods are fast disappearing in the space age, which can be said to have started after World War II. The introduction of electronics in the survey equip-ment, in the space age, is said to have revolutionised the methods and techniques of survey work. With these electronic surveying equipment very long lines of the order of even thousands of miles can be measured with reasonable accuracy, in less time. This will be certainly helpful in the inter-continental connections, and also for making one world geodetic system. In the case of astronomical methods also new tech-niques like star osculation, solar eclipse, moon camera etc. methods have been developed for the same purpose. Now atomic times. used for obtaining the exact longitudes. Modern angle measuring instruments and the use of better telescopes are improving the astronomical methods. Started in the beginning of the twentieth century and perfected in the space age is the Photogrammetry, a new tool of geodesy. Though the procedures of this technique is entirely different than the other branches of geodesy, its practical function is the same. Instrumental and analytical aero triangulation are important in extending ground control of second order geodetic standards. Automation in Photogra-mmetric processes, which has come in this space age, is worth noting. Physical geodesy, the basis of which is the measu-rement of gravity on earth, is the most powerful part of geodesy in the present age. Its purpose is not only to get the shape of earth as geoid, but its introduction in obtaining the deviations of the vertical, has improved the accuracies of the surveyed points, got by other methods like astronomical, triangulation etc. The old limitations in this. branch also are fast disappending and the gravity can now be measured at sea and from air. Now the first problem of physical geodesy is to , fill the big gaps of unsurveyed parts and to cover the entire earth with a good net of gravity material. The most recent branch of geodesy is the satellite geodesy. This is only in the infant stage now, but this will become a powerful branch in geodesy in future. Special geodetic satellites should be launched into space for our purpose, and with the cooperation of many organisations the first geodetic satellite was launched in 1962. Still many launches are required for obtaining all the parameters of the earth accurately. Whatever may be the method used, it is very necessary to have all systems to be converted to one world geodetic system. In this space age, no country can have its own system as this will cause difficulties in aviation, navigation etc. For a14 reaching this goal mutual cooperation among various. countries is unavoidable and better educational facilities and research work will improve the situation. Lastely it can be said that space age has added much for geodesy and the importance of geodesy will be realised still more in future.