Thanks Martin, as I said I thought that was the case but im edgy about doing mass translations with FME
-----Original Message----- From: Martin Higham [mailto:[EMAIL PROTECTED] Sent: Thursday, 14 April 2005 10:59 AM To: Ellingham Morgan Subject: RE: MI-L Changing Projections Hi Morgan, Assuming your data is correctly positioned with relation to AGD66; when you reproject to GDA94 new coordinates are written for the map objects, the new datum is noted in the header of the map file and your data will then be positioned correctly in the new datum. If your geographic data is x and y columns in a database, then (using MapInfo) you'll need to create points for these, do the reprojection then populate new columns with the new coordinates (using MapInfo's coordinate extractor tool). Of course, if you need the best accuracy then you need to perform a grid-based transformation rather then the generic datum translation that MapInfo offers. There is free software (eg. DatumTran from NSW dept of lands) to do grid-based transformations. Does this clear things up ? Best Regards, Martin Higham Avantra Geosystems ph (61 3) 8504 0428 0425-730-428 fx (61 3) 9596 7997 www.avantra.com.au > -----Original Message----- > From: Ellingham Morgan [mailto:[EMAIL PROTECTED] > Sent: Thursday, 14 April 2005 10:29 > To: [email protected] > Subject: MI-L Changing Projections > > > This is probably really obvious but ive got a mental block on this - > when changing projections do the 'actual' X , Y's / E, N's change or do > they stay the same but relate to a different position on the datum? Its > giving me a headache.... We've got heaps of point data with X, Y's > associated with them and they need to be changed from AGD to GDA, I need > to know if I have to do a coordinate extract as well as a reproject? I > am 90% they do change but I would love some more expert opinions. > > Regards... > > > Morgan Ellingham > > GIS Technical Officer > > Level 1, 150 Jolimont Rd, East Melbourne > > Ph: (03) 9261 5065 > > Mob: 0419 145 666 > > Email: [EMAIL PROTECTED] <mailto:[EMAIL PROTECTED]> > > > --------------------------------------------------------------------- List hosting provided by Directions Magazine | www.directionsmag.com | To unsubscribe, e-mail: [EMAIL PROTECTED] For additional commands, e-mail: [EMAIL PROTECTED] Message number: 16083
