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I am looking for an algorithm for finding GPS coordinate of a point on a straight line defined by say points p1 and p2 at distance r from p1. GPS coordinate of p1 and p2 are known. I searched a lot on web but couldn't find any well explanatory answer. I found an answer which was solving it just like Cartesian coordinates. But I don't think its correct as GPS coordinated system is not analogous to Cartesian coordinate system.

Chor Sipahi
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  • http://stackoverflow.com/questions/365826/calculate-distance-between-2-gps-coordinates – Untitled123 Dec 27 '15 at 23:11
  • @Untitled123 Thanks for the link. How does that answer my question? – Chor Sipahi Dec 28 '15 at 01:56
  • I thought the math might be helpful since it's probably the same. If I was to venture a guess, I'd say that solving it is very similar to the Cartesian coordinate method. If anything, you could flatten the Earth out and just treat it as flat. Out of curiosity, why are you doing this? – Untitled123 Dec 28 '15 at 01:58
  • @Untitled123 yes this gives one equation that's for distance. But we need another equation similar to slope in Cartesian system. I am looking for that other equation. But now I got the answer while searching look at this: http://www.movable-type.co.uk/scripts/latlong.html MBo has also answered with this. – Chor Sipahi Dec 28 '15 at 06:23

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You can find all necessary information on this excellent site.
Look at section Bearing, then Destination point given distance and bearing from start point.

You might probably be interested in Intermediate point, that finds point at any fraction of the big circle arc.

MBo
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  • Thanks for the response. I tried the function for intermediate points provided at this link. See the points betow. Pt1: 40.724559363593656,-73.99463653564453 Pt2: 40.730776232169404,-73.99118429167612 Pt3: 40.736992997874594,-73.98773140256424 Pt4: 40.74264002709531,-73.98459434509277 I started with Pt1 and Pt4 and got Pt2 and Pt3 as intermediate point so that distance between any consecutive point is less than or equal to 750m. You can check plotted points [here](http://www.darrinward.com/lat-long/?id=1680642). Points r bit deviated from st. line. Can you help with getting more accuracy? – Chor Sipahi Dec 29 '15 at 02:18
  • Have you found bearing P1-P4, then find P2 and P3 as 750 and 1500m at that bearing from P1? And I see that points are on the same straight line (as expected for small distance and near-meridional direction) – MBo Dec 29 '15 at 02:35