Calculating Bearing

[AJF]

I need helps here,

 

If I am at Lat1, Lon1 and whant to go to Lat2,Lon2 how do I calculate the bearing.

I know that I can use Trigonometry and that is fine but I don't remember how to.

 

the format is dd.mmmmmm

 

If anybody can help I would really appreciate it.

 

Thanks,

 

AJF

[+Hard Oiler]

Lot's of ways but this handy little utility will do it for free:

 

http://www.fizzymagic.net/Geocaching/GeoCalc/GeoCalc.html

[+EScout]

Enter each of the coords and save as waypoints in your GPSr. Go to your route function, and start a new route. Enter the 2 waypoints and save the route. When you highlight the first waypoint, it gives the bearing and distance to the second. Make sure you set up your North Reference to either True or Magnetic, depending on what you want.

[AJF]

Thanks guys,

 

But I need the formula, I'm finishing a program for my HP 2215 and that is the only thing left to do.

 

Thanks

[+papatom2]

This is for great circle distance and bearing.

 

1. cos(D) = (sin(A) * sin() + (cos(A) * cos( * cos(L))

 

2. cos© = (sin( - (sin(A) * cos(D))) / (cos(A) * sin(D))

 

WHERE:

 

A = YOUR latitude in degrees.

B = latitude of the other location in degrees.

L = YOUR longitude minus that of the other location. (Algebraic difference.)

D = Distance along path in degrees of arc.

C = True bearing from north if the value for sin(L) is positive. If

sin(L) is negative, true bearing is 360 - C.

 

To convert degrees of arc to statute miles, multiply by 69.041.

To convert degrees of arc to kilometers, multiply by 111.111.

Edited June 8, 2005 by papatom2

[+diverhank]

Here's a good website for formulas:

 

http://williams.best.vwh.net/avform.html

[+Lil Devil]

A = YOUR latitude in degrees.

B = latitude of the other location in degrees.

L = YOUR longitude minus that of the other location.

Ummm, I think these are supposed to be in radians.

At least that's what I have in the source code for GPX Spinner. I'm too lazy to research the formulas again, though. All I know is my code works

[JDMC]

Here's another good website, with the formula:

 

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

[+blindleader]

You don't want to use the spherical earth model if you can help it, though the calculations are easy. I did it for hand held calculators 25 years ago.

 

An elliptical model, specifically GRS80/NAD83/WGS84 is what is needed. The Ed Williams web site linked above used to have some good reference links but many of them are defunct. I wish I still had the reference from which he wrote his Great Circle Calculator. Hmmm, maybe this is the venerable old document you want. I can almost smell the mildew . You could also reverse engineer the javascript, or at least mine it for a good set of ellipsoid parameters.

 

Another bit of software you might be interested in is compsys21. It has a clunky user interface, but does all types of geodetic intersections. I still haven't found a source for those formulas either. The FAA web site is huge and hard to search.

 

edit: The site JDMC linked for the spherical solution also has the Vicenty formulae for the ellipsoidal solution.

Edited June 9, 2005 by blindleader

[AJF]

Thank you guys,

 

now I have a wealth of information to go on.

 

This place has a great deal on information and people who are willing to help.

 

Thanks again.

[AJF]

A = YOUR latitude in degrees.

B = latitude of the other location in degrees.

L = YOUR longitude minus that of the other location.

Ummm, I think these are supposed to be in radians.

At least that's what I have in the source code for GPX Spinner. I'm too lazy to research the formulas again, though. All I know is my code works

Your rigth Lil Devil it's Radians.

 

Thanks

[+papatom2]

QUOTE (Lil Devil @ Jun 8 2005, 02:47 PM)

QUOTE (papatom2 @ Jun 8 2005, 03:20 PM)

A = YOUR latitude in degrees.

B = latitude of the other location in degrees.

L = YOUR longitude minus that of the other location.

 

Ummm, I think these are supposed to be in radians.

At least that's what I have in the source code for GPX Spinner. I'm too lazy to research the formulas again, though. All I know is my code works biggrin.gif

 

Your rigth Lil Devil it's Radians.

 

Thanks

 

Radians and degrees are directly proportional so there is no difference in the calculations. Use either one.

[+Deneye]

And if you don't want the formula but still want to run the calculation, try this place:

 

one of many calculators