Bangalore, India
GT_COORDTRAN
Important note: If you need more information about this command or detect a malfunction in this command, please email me immediately : rakesh.rao(at)4d-technologies.com
GT_COORDTRAN-the geographic coordinate transformation engine, is yet another new addition in GeoTools V14. It is available under the GeoTools->Geographic menu and provides options to convert between the following coordinate systems:
- Lat-Longs (geographic)
- UTM (Universal Transverse Mercator)
- Transverse Mercator
- Lamberts Conformal Conic
- Albers Equal Area Projection
Coordinate transformation is a complex mathematical operation involving a bunch of arithmetic and trignometric functions. To use GT_COORDTAN, you will need to know exactly what projection system your existing coordinates are in an what system you want it to be transformed to. You will also need to know which spheroid (and datum) your data should be in.
All these and more are specified in the setup dialog which is started using the GT_COORDTAN_SETUP command (see below).
Please remember that the transformation parameters must be set with care and caution. If you are doing UTM2Geo or Geo2UTM transformation, you must specify the zone number correctly. You may use the following UTM Zone chart to determine your UTM zone:
Figure 1: UTM Zone Map: Source: Wikipedia
Datum Shift (Change) operation:
Sometimes, you may end up with a drawing that is in the correct projection system, but based on a wrong datum. If you want to convert this data to the correct datum, you need to apply a datum shift. GT_COORDTAN supports two popular datum shift transformation:
- Bursa-Wolf (Helmert) 7-parameter transformation
- Molodensky-Badekas 10-parameter transformation
Credits and Acknowledgements
I wish to place on record the valauble help received from David Allison of the University of South Alabama and the paper "Map Projections - A Working Manual" by J.P.Snyder, published by the United States Geological Survey. I am also grateful to Ray Moran of Optus Telecom, Australia who has tirelessly tested all the new routines in GeoTools V14 and also provided many useful links, references and ideas to help develop the new routines.
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very nice
Posted by: ibrahim oraby | March 13, 2018 at 16:42