Hi Lars, Thanks for your reply.
I may use some of your ideas to help me solve this. My application is in C++ using MapX, so I have to use the functions available in MapX. The calculation has to be done in code and quickly. I was thinking I could use your idea of converting the point to a meter grid point and then applying trig to get the second point and then converting the new point back to WGS84. The trig part is ok. I now need to know how to convert between WGS84 lat/long and a meter system - probably UTM. Does anyone know how this is done? Cheers Tim -----Original Message----- From: Lars V. Nielsen (GisPro) [mailto:[EMAIL PROTECTED] Sent: 29 June 2004 16:45 To: Tim Smith Cc: [EMAIL PROTECTED] Subject: Re: MI-L New lat/long from distance/bearing Hi Tim, If you don't want to go all out on formula gymnatics, I may have an idea for you. By using the coordinate support in MapInfo to my advantage, I've implemented adding meter offsets to GPS positions this way : 1. Set the coordsys to LatLong/WGS84, and obtain the coordinates of the point (user click in my case) 2. Switch the coordsys to a meters based stereographic projection with the lat/long point as center, i.e. as (0,0) 3. Create a new point feature using simple 2D geometry, e.g. 300 meters east, 200 meters south, i.e. in stereographic position (300,-200) 4. Switch back to LatLong/WGS84, and retrieve the coordinate of the created point feature 5. Voila, you've had MapInfo calculate a flat offset to a geographic position. It was implemented in Pro/MapBasic, which is far better at this this MapX. But even in MapX you can manipulate the coordinate system setting to your advantage, and you can create point features on the fly, so it ought to be possible even in MapX to use the above method. And yes, it's an approximate method that deteriorates with distance, but for smaller offsets it should be perfectly ok to use. Good luck. Best regards/Med venlig hilsen Lars V. Nielsen GisPro, Denmark http://www.gispro.dk/ ----- Original Message ----- From: "Tim Smith" <[EMAIL PROTECTED]> To: <[EMAIL PROTECTED]> Sent: Tuesday, June 29, 2004 1:42 PM Subject: MI-L New lat/long from distance/bearing Hi List, I have a latitude and longitude in WGS-84. I want to calculate a new point based on a bearing and distance from this position. Difficult bit - I want to calculate this using MapX, or alternatively I could use some C/C++ code. Thanks for any help with this Kind regards Tim Smith --------------------------------------------------------------------- List hosting provided by Directions Magazine | www.directionsmag.com | To unsubscribe, e-mail: [EMAIL PROTECTED] For additional commands, e-mail: [EMAIL PROTECTED] Message number: 12390 ______________________________________________________________________ This email has been scanned by the MessageLabs Email Security System. For more information please visit http://www.messagelabs.com/email ______________________________________________________________________ --------------------------------------------------------------------- List hosting provided by Directions Magazine | www.directionsmag.com | To unsubscribe, e-mail: [EMAIL PROTECTED] For additional commands, e-mail: [EMAIL PROTECTED] Message number: 12429
