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    <p>Your problem can be solved by taking the following steps.</p> <ul> <li><p>Calculate the distance from points A and B (use the <a href="http://www.movable-type.co.uk/scripts/latlong.html">Haversine formula</a>, which is good enough here, or the more complicated <a href="http://www.movable-type.co.uk/scripts/latlong-vincenty.html">Vincenty formula</a>). To use the formula correctly, Android's microdegrees, which is what getLatitude and getLongitude return, must be converted to radians, using a formula like this:</p> <pre><code> double radians = Math.toRadians((double)microdegrees/1000000); </code></pre></li> <li><p>Calculate the bearing (direction) from points A and B (use the formula on the same page). This will be different from the Pythagorean formula because the earth is round, not flat.</p></li> <li>Then you can choose a new distance and calculate point X given point A and the bearing found in the previous step (see either "Destination point given distance and bearing from start point" on the same page, or <a href="http://www.movable-type.co.uk/scripts/latlong-vincenty-direct.html">Vincenty's direct formula</a>).</li> <li><p>Convert the radians from the generated point into microdegrees using this formula:</p> <pre><code> int microdegrees = (int)(Math.toDegrees(radians)*1000000); </code></pre></li> </ul> <p>Putting it all together, we have the following function, which I place in the public domain:</p> <pre><code> public static int[] getIntermediatePoint( int startLatMicroDeg, int startLonMicroDeg, int endLatMicroDeg, int endLonMicroDeg, double t // How much of the distance to use, from 0 through 1 ){ // Convert microdegrees to radians double alatRad=Math.toRadians((double)startLatMicroDeg/1000000); double alonRad=Math.toRadians((double)startLonMicroDeg/1000000); double blatRad=Math.toRadians((double)endLatMicroDeg/1000000); double blonRad=Math.toRadians((double)endLonMicroDeg/1000000); // Calculate distance in longitude double dlon=blonRad-alonRad; // Calculate common variables double alatRadSin=Math.sin(alatRad); double blatRadSin=Math.sin(blatRad); double alatRadCos=Math.cos(alatRad); double blatRadCos=Math.cos(blatRad); double dlonCos=Math.cos(dlon); // Find distance from A to B double distance=Math.acos(alatRadSin*blatRadSin + alatRadCos*blatRadCos * dlonCos); // Find bearing from A to B double bearing=Math.atan2( Math.sin(dlon) * blatRadCos, alatRadCos*blatRadSin - alatRadSin*blatRadCos*dlonCos); // Find new point double angularDistance=distance*t; double angDistSin=Math.sin(angularDistance); double angDistCos=Math.cos(angularDistance); double xlatRad = Math.asin( alatRadSin*angDistCos + alatRadCos*angDistSin*Math.cos(bearing) ); double xlonRad = alonRad + Math.atan2( Math.sin(bearing)*angDistSin*alatRadCos, angDistCos-alatRadSin*Math.sin(xlatRad)); // Convert radians to microdegrees int xlat=(int)Math.round(Math.toDegrees(xlatRad)*1000000); int xlon=(int)Math.round(Math.toDegrees(xlonRad)*1000000); if(xlat&gt;90000000)xlat=90000000; if(xlat&lt;-90000000)xlat=-90000000; while(xlon&gt;180000000)xlon-=360000000; while(xlon&lt;=-180000000)xlon+=360000000; return new int[]{xlat,xlon}; } </code></pre> <p>And here's how it's used:</p> <pre><code>int ax = oldPoint.getLatitude(); int ay = oldPoint.getLongitude(); int bx = currentPoint.getLatitude(); int by = currentPoint.getLongitude(); long at = oldPoint.getDataRilevamento(); //get time first point long bt = currentPoint.getDataRilevamento(); // get time second point long xt = x.getDate(); // time of point to find // Find relative time from point A to point B double t=(bt==at) ? 0 : ((double)(xt-at))/((double)(bt-at)); // Find new point given the start and end points and the relative time int[] xpos=getIntermediatePoint(ax,ay,bx,by,t); x.setLatitude(xpos[0]); //set the latitude of X x.setLongitude(xpos[1]); // set the longitude of X </code></pre>
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    1. POHow to find a geographic point between two other points
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    1. USPeter O.
    1. USPeter O.
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    1. POHow to find a geographic point between two other points
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    1. COYou're great!!! Really really thank you!
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      1. USMarco Fedele
    2. COThank you for posting this algorithm. I was needing to do something similar for my project and I believe this would do! Do you mind if I wrap this up and publish it as a npm module?
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      1. USSoichi Hayashi
 

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