Ho to get Heading Direction from from 2 lat,long points

[abhishek]

i am doing a live 3d map based on live gps points from a moving car.

how to get  heading direction (x degrees from north) so that i can set the lookAt point towards correct heading direction.

 

Can i get heading direction from 2 gps points (lat,long) -> (lat,long)

 

i also wants to move nicely on the road and i am using (speed_teleport) as setflytospeed option. Any way to set the speed of this teleport?

i dont want to pan with zooming in and out, i just want to move my car on streets looking from back at 45 degrees.

 

[StarTraX]

You have to use trigonometry.
Working in radians, not degrees, and assuming the two points are
fairly close: metres not 100's of kilometres (to ensure cos(lat1) is
much the same as cos(lat2)) then:
tan(heading angle) = (lon2 - lon1)*cos(lat1)/(lat2 - lat1)
You'll have to use the math.atan2 function to get the correct sign on
the result.

[abhishek]

Hi thanks star thanks,

 i think i worked it out..

from the trignometry of course .. luckly javascript Math object gives all the functions we need to do it...

 

 

 

 

[Stanislav Chachkov]

You can use createVantageView from gex http://code.google.com/p/earth-api-utility-library/

[abhishek]

thanks for that

i also found one link - very helpful

http://www.movable-type.co.uk/scripts/latlong.html

 

though i am sticking to my java code for now as its working fine :

function GetDirection(lat1, lon1, lat2, lon2) {

var br = 0;

br = Math.atan2(Math.sin(lon2 - lon1) * Math.cos(lat2), Math.cos(lat1) * Math.sin(lat2) - Math.sin(lat1) * Math.cos(lat2) * Math.cos(lon2 - lon1)) % (2 * Math.PI);

br = (br * 180) / Math.PI;return br;

}

[gautam yadav]

thanks abhisek
it's working fine

[gautam yadav]

Since atan2 returns values in the range -π ... +π (that is, -180° ... +180°), to normalise the result to a compass bearing (in the range 0° ... 360°, with -ve values transformed into the range 180° ... 360°), convert to degrees and then use (θ+360) % 360, where % is modulo.

For final bearing, simply take the initial bearing from the end point to the start point and reverse it (using θ = (θ+180) % 360).

[bimat]

Hi thanks,

http://vn-sport.com

Vào 18:13:46 UTC+7 Thứ bảy, ngày 15 tháng chín năm 2012, gautam yadav đã viết: