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Software Development and Validation for Geodetic Datum Transformations By Venkat Ramanan*, T.Vamsi* Under the guidance of Prof M N Kulkarni*, Dr Tibor borsa** * IIT Bombay, ** Satellite geodetic observatory. Contents. Problem Statement Theory Software Developed Results & Conclusion.
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Software Development and Validation for Geodetic Datum TransformationsBy Venkat Ramanan*, T.Vamsi* Under the guidance of Prof M N Kulkarni*, Dr Tibor borsa*** IIT Bombay, ** Satellite geodetic observatory
Contents • Problem Statement • Theory • Software Developed • Results & Conclusion
The Problem statement • Why transformation is needed? • Coordinates given by GPS on WGS-84 Global Datum • National maps on national- local datum • Estimation of precise transformation parameters between national geodetic datums and the world geodetic system 1984(WGS-84)
Theory • Transformation parameters • 7 Transformation parameters • 3 Translations dx,dy,dz • 3 rotations about x, y and z axes • 1 scale factor
Steps involved in transformation The transformation from one projection system to any other projection system can be performed as it follows: • From projections system1 to its corresponding datum, say datum1 • From datum1 to one of Global reference frames (Say to WGS-84) • From global reference frame to the Datum of interest. Say datum2, • From Datum2 to the projection system in goal.
Procedure Involved • The first and the last steps are accomplished using appropriate formulae. • For steps 2 and 3 Least square adjustment has been used
Formula for transformation |XGlobal| |dx| | 1 EZEY | |XHD-72| |YGlobal| = |dy| + (1+k) | -EZ 1 EX | |YHD-72| |ZGlobal||dz| | Ey -Ex1 | |ZHD-72| where
Software • Developed in C programming language in UNIX platform • Methodology of the Software * Points Database required * Chooses the nearest points within a range of 20km * Min. of 3 points required.
Sample Input and Output Point GPS coordinates X Y Z Pili 4082873.474 1454082.764 4664021.508 Penc 4052392.820 1417750.672 4701415.990 Tisz 4052457.444 1518221.640 4669885.105 Point Local coordinates X Y Z Pili 4082870.524 1454084.764 4664020.878 Penc 4052388.355 1417749.104 4701410.778 Tisz 4052453.964 1518220.270 4669888.242
Results The output for the point- Penc was as follows : X = 4052388.378 Y = 1417749.100 Z = 4701410.756
Conclusion • The software can transform coordinates accurately between any 2 datums • More effective, if made into an executable file.
Acknowledgements • The work was carried out in the Satellite Geodetic Observatory, Hungary, under the MOU signed between IIT Bombay & Technical Univ. of Budapest and the Indo-Hungarian joint project on research in space geodesy
Thank you Any questions ?