GPS cordinates wizz ?

[ThomasScherrer 0]

hello, I am looking for a GPS cordinate wizzard :-)

The task is explained quite simple:

Find distance and angle to a given WGS84 location.

it must work all over the globe.

I am not looking for super hi resolution in the angle,

since I only have 8 or 16 arrows to show the "goto" direction.

the distance a 10m resolution is fine.

[Mr.RC-Cam 121]

Maybe this will help with your great circle quest?: http://williams.best.vwh.net/avform.htm

[ThomasScherrer 0]

yes thanks,

I was looking for something much more simple,

since I dont need nice nice resolution,

a simply 2D vector to angle is all I need, I guess.

[cyber-flyer 1]

If you just need a direction, you can build a look up table.

If you are planning to use the device at about the same latitude you can simply compare (delta latitude) and (delta longitude) * (cosine factor).

[ThomasScherrer 0]

well it would be nice if it could be world wide first time :-)

i was also thinking about calculating the deltas, if increasing if go away,

if decreasing I go home.

[cyber-flyer 1]

Then the exact formula is:

(course over ground (from GPS)) - arctan((delta longitude) * cos(latitude)/(delta latitude) )

both arctan and cos can be approximated with lookup tables to a desired precision.

[ThomasScherrer 0]

the math problem has been fixed by a really cool programmer

http://www.webx.dk/rc/video-wireless/homeagain.wmv

now our OSD board can display distance to home,

and direction to home, this is the very first screenshoot you will get !

first we test if the little arrow on top is enough,

or the much higher resolution gfx slider pin at the bottom is fine or need to be bigger.

Home is defined as the first good stable position at each powerup.

[Terry 5]

Looks good. The little arrow is good, don't want to clog up the screen for no reason.

Terry

[ThomasScherrer 0]

you are right, 1 of 8 arrows are fine resolution to get home I think.

I drove to work with it installed in my car hehe

I was eger to look at the screen while driving, kinda cool.

there is a big difference from drivning to flying a little model plane.

so the hi-res angle thing must go when flying, no real use I say.

I can even input waypoints to my work or a friend or whatever,

and then find my way :-) Really cool.

[Mark Harris 0]

I think just the arrow but not for screen clog. the little line scrolling around for me is going to make me crash because its distracting! haha.

[dalbert02 0]

Any new developments on your project? Did I miss a new thread?

Thanks,

-dave

[Kilrah 2]

12 pages for you:

http://www.rc-cam.com/forum/index.php?showtopic=1915

[mieczotronix 0]

the math problem has been fixed by a really cool programmer

I've been just trying to work out a solution for the same problem (codable with fixed precision maths in Atmega)

Could you provide a glimpse on how to do it (don't need a worldwide solution)?

[FredericG 0]

I've been just trying to work out a solution for the same problem (codable with fixed precision maths in Atmega)

Could you provide a glimpse on how to do it (don't need a worldwide solution)?

In the beginning of this year I also developed code to calculate distance and direction with just 32 an 16 bit integer maths. http://www.rcgroups.com/forums/showthread.php?t=629356

From time to time I get requests for the code. I was planning to make small document that explains it.

Frederic