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POUsing a GeoPoint location and meters X/Y, how can a Longitude/Latitude be calculated?
 

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  1. POUsing a GeoPoint location and meters X/Y, how can a Longitude/Latitude be calculated?
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    <p>I have a little project I've been playing with (Android, GPS, mapping APIs), and I need to figure how to find a longitude/latitude/GeoPoint from a given longitude/latitude/GeoPoint with only knowing the meters/km longitude and latitude. e.g. I want to figure out where a point is from me, that I know is +1000 meters along the longitude and +1000 along the latitude.</p> <p>It's a little different than the usual GeoPoint/distance questions you'll see, and it's not quite geo fencing radius related as the distance is X,Y meters/kms, and I don't have a bearing. (I could work out a bearing, but I don't have a suitable direct distance)</p> <p>Basically, if I could reverse GeoPoint.distanceTo() it would do the job for me.</p> <p><strong>Update</strong></p> <p>Just a little more background. I'm basically applying a node triangulation idea I had, but the algorithm requires that my inputs be in a map normalized form that's not the same as longitude and latitude. I create a map/grid where 0,0 (the bottom/left) is the left/west and bottom/south most longitude/latitude values from the nodes I'm working with. All the other node X/Y on the map are determined by finding their meters from the 0,0 node's longitude/latitude using GeoPoint.distanceTo(). (note that I find their X/Y by performing distanceTo twice for each node so I have the X and Y meters from 0,0, not a direct line to the node) That distance in meters is fed into the algorithm and new X/Y map points are produced.</p> <p>And so I need to figure out how to convert distance from a longitude/latitude into another, previously unknown, longitude/latitude.</p> <pre><code>double startPointLongitude = 23.459821; double startPointLatitude = 76.998200; double distanceLongitude = 100; // 100 meters along the longitude double distanceLatitude = 75; // 75 meters along the latitude </code></pre>
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    1. USgarlicman
    1. USgarlicman
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    1. CONote that order matters, you will arrive at different points if you go north then east and east then north.
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      1. POUsing a GeoPoint location and meters X/Y, how can a Longitude/Latitude be calculated?
      1. USHenry
    2. COThe problem is I'm not even sure if using a north and east bearing will work correctly. I believe that a compass doesn't perfectly align with the lines on which longitude and latitude run. Meaning latitude would run with the curve of the earth while north would be a direct line to a point. I could be wrong. but even if I whipped up a test, I wouldn't know if my results would be correct.
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      1. POUsing a GeoPoint location and meters X/Y, how can a Longitude/Latitude be calculated?
      1. USgarlicman
    3. COFor hundreds of meters, you can convert the cartesian coordinates to [polar ones](http://en.wikipedia.org/wiki/Polar_coordinates). The error will be negligible. For greater distances you'll run into trouble, since the Earth is not a perfect sphere but an ellipsoid. GMaps use [WGS84](http://en.wikipedia.org/wiki/WGS84) as reference.
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      1. POUsing a GeoPoint location and meters X/Y, how can a Longitude/Latitude be calculated?
      1. USMister Smith
 

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