Simple solution - joint the "Flat Earth Society"... http://www.flat-earth.org/
MidNight Mapper Aka neil -----Original Message----- From: Dan Bowles [mailto:[EMAIL PROTECTED] Sent: Tuesday, November 09, 2004 7:31 AM To: Bill Thoen Cc: MapInfo-L Subject: RE: MI-L Question for Real Surveyors Bill I work at a survey firm so have forwarded your email around for a response, hopefully you should get one soon. I would suggest that your problem is to do with scale factor. For example with a 6 degree UTM projection, the scale factor at the central meridian is 1 so you will have no distortion. However, at the edge of the zone the scale factor could be 0.994, meaning that for every 1000 m you measure you'll be 6 m out from the real position of your measurement. In NSW, where I live, surveyors use a 2 degree TM system to create a more accurate projection, at the edge of these zones the scale factor may be 0.9994. So for every 1000 m measured you'll only be 0.6 m out. A much more effective result. See below for our surveyors answer. Lazy bastards only use cartesian, but it's certainly a good way of solving the problem. Dan, In most of the surveys which we undertake we do not worry about the curvature of the Earth. This includes surveys up to 3 km's in the length of boundaries etc. This would provide a zero misclose in the quoted case. Cooko Dan Bowles BSc GIS Officer Harper Somers O'Sullivan PO Box 428 HAMILTON NSW 2303 E [EMAIL PROTECTED] <mailto:[EMAIL PROTECTED]> T 02 4961 6500 M 04 3834 8372 --------------------------------------------------------------------- List hosting provided by Directions Magazine | www.directionsmag.com | To unsubscribe, e-mail: [EMAIL PROTECTED] For additional commands, e-mail: [EMAIL PROTECTED] Message number: 13961
