Re: Distance between two GPS points. - Algorithms Discussion Boards

hai all,
is it possible to find the distance in meters between the two points if i have, their longitude, latitude and height.
iam aware that, the distance between two adjacent graticules is not standatd in all the places on the earth. but, based on the height, can we do any thing?
thanks for your views.

Thinking out of the box, but I believe when you have 180° for the meridian and 360° for the equator (or vice versa)you have a full circle, right?
You could also find the circumference of the earth on google. Divide the circumference with 180° or 360° and that should give you (roundabout) the distance for 1° for your X axis and Y axis than you can use vector calculation to calculate the distance between 2 points.

I do think my idea is correct, BUT it is probably inaccurate.

V.
If I don't see you in this world, I'll see you in the next one... And don't be late. (Jimi Hendrix)

we can do this,
but iam not sure weather this applies through out the globe.
any way, thanks for your response.

I can, 100% sure. Just show me what and how GPS bases on, I'll find a way.

Are you talking points that are close, or anywhere on Earth; that is, are you wanting to take into account the curvature of the Earth?

Another question: Are you talking about the great-circle distance (around the curvature of the Earth), or a straight line (which would have to tunnel thru the Earth if distances are very far)?

David

Ha has a neutrino gun!
Big Grin | :-D

If the Lord God Almighty had consulted me before embarking upon the Creation, I would have recommended something simpler.
-- Alfonso the Wise, 13th Century King of Castile.

CPallini wrote:
Ha has a neutrino gun!

dagnabbit! I want one!!!!

Big Grin | :-D

_________________________
Asu no koto o ieba, tenjo de nezumi ga warau.
Talk about things of tomorrow and the mice in the ceiling laugh. (Japanese Proverb)

chandu004 wrote:
is it possible to find the distance in meters between the two points if i have, their longitude, latitude and height.

The short answer: Yes.

The long answer: you need to deal with great-circle (geodesic solution) calculations. See: http://mathworld.wolfram.com/GreatCircle.html[^]

There is also an iterative solution that is often used for boat/air travel. Obviously continuously changing your heading to provide the absolute shortest route to the meter is difficult. So you create waypoints travel to them, change heading and travel to the next, etc., until you reach your destination. This has become easier with computers because a computer auto-pilot will auto-navigate to many more waypoints with micro changes in heading to keep a shorter path. But with ocean travel that is somewhat more difficult.

The question becomes how accurate do you need it, and what is the purpose of the answer. The piece-wise iterative approach would be:

<br />
surfacedistance(from: lat, lon, alt; to: lat, long, alt)<br />
{<br />
 distance= ECEFdistance(ecef(to),ecef(from));<br />
 // choose your desired approximation level for accuracy<br />
 if (distance<1000) return distance;<br />
// else recurse and use piecewise approximation<br />
 ecef_mid=ecef_to*0.5+ecef_from*0.5;<br />
 spher_mid=togeodetic(ecef_mid);<br />
 spher_mid.alt=from.alt*0.5+to.alt*0.5;<br />
 return surfacedistance(from,spher_mid)+surfacedistance(spher_mid,to);<br />
}<br />

or something similar (that is off the top of my head, google piecewise approximation of geodesic distances. The idea is that you can sum a series of vector distances in local space and the more accurate your division, the more accurate the answer. You can choose speed over accuracy at any point by changing the approximation distance change between mid-point division and vector-distance.

The bad news is, if you set the value too low, it is a heavy recursion level and you are better off calculating it directly. There are times in implimentation you may want to do either for other reasons related to use of the answer.

_________________________
Asu no koto o ieba, tenjo de nezumi ga warau.
Talk about things of tomorrow and the mice in the ceiling laugh. (Japanese Proverb)

chandu004 wrote:
is it possible to find the distance in meters between the two points if i have, their longitude, latitude and height.

Like these:

http://mathforum.org/library/drmath/view/51720.html

http://jan.ucc.nau.edu/~cvm/latlongdist.html

http://mathforum.org/library/drmath/view/51711.html

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

http://mathforum.org/library/drmath/view/54680.html

http://www.freevbcode.com/ShowCode.asp?ID=5532

http://mathforum.org/library/drmath/view/51717.html

http://www.meridianworlddata.com/Distance-Calculation.asp

http://mathforum.org/library/drmath/view/51722.html

http://www.csgnetwork.com/longlatdistance.html

http://mathforum.org/library/drmath/view/54941.html

http://www.csgnetwork.com/lldistcalc.html

http://mathforum.org/library/drmath/view/54680.html

"Normal is getting dressed in clothes that you buy for work and driving through traffic in a car that you are still paying for, in order to get to the job you need to pay for the clothes and the car and the house you leave vacant all day so you can afford to live in it." - Ellen Goodman

"To have a respect for ourselves guides our morals; to have deference for others governs our manners." - Laurence Sterne

thanks a lot david,
one of the above links helped me to understand many interesting points.
and the logic worked for some of hte examples, so far i have tested.

chandu004 wrote:
and the logic worked for some of hte examples, so far i have tested.

the logic should work quite well. I haven't gone through most of the links, but I checked a few of them. I am not sure what you need the answer for, but it would be wise to clarify that your answer is for a spherical Earth not an ellipsoidal model. At least the ones I followed so far assume a spherical earth. This is a decent approximation, but again, it depends on what you are trying to do. No answer will be exactly right because even an ellipsoidal model is an approximate surface. The true surface is mapped in elevation points to the geoid.

_________________________
Asu no koto o ieba, tenjo de nezumi ga warau.
Talk about things of tomorrow and the mice in the ceiling laugh. (Japanese Proverb)

You probably know that the "standard distance" for 1 nautical mile is 6076.115 feet. And that 1 degree of latitude is 60 Nautical miles (NM). There is no "standard" for longitude since it is wider at the equator and they all conjoin at the poles to zero distance. I think there is a formula for determining the length of 1 degree of longitude based on the latitude where the longitude is taken, but don't know it offhand. If you are somewhere in the range of 30 to 60 degrees latitude, the "standard distance" formula will get you close to the correct distance between two points.

John P.

the easiest way to do it (assuming spherical earth)is to convert the lat-lon values into X-Y-Z values.
The center of the earth is (0,0,0),
the intersection of the prime meridian and the equator is (R,0,0)
lat 0, lon +90 is (0,R,0),
the north pole is (0,0,R)
the south pole is (0,0,-R)

where R = radius of earth

to go from lat lon to x y z is:
x = R * Cos(lon) * Cos(lat)
y = R * Sin(Lon) * Cos(lat)
z = R * Sin(lat)

You do that for point 1 and point 2, then determine the distance between them (straight line)
x' = x2-x1
y' = y2-y1
z' = z2-z1

d = sqrt((x'*x')+(y'*y')+(z'*z'))

One half of the angle from point 1 to point 2 is

a = ArcSin(d/2R)

to get the great circle distance take this angle (in radians), double it to get the actual angle, them multiply if by the radius of the earth

D = 2 * a * R

where D is the distance you are looking for.

Hi guys,

Anybody knows some method to convert free hand curve to bezier curves ?
Please reply..

Thanks,
kd

If u can Dream... U can do it

What about Least Squares Fit?
Smile | :)

If the Lord God Almighty had consulted me before embarking upon the Creation, I would have recommended something simpler.
-- Alfonso the Wise, 13th Century King of Castile.

Thanks for a hint CPallini Rose | [Rose]

, I will look it.

If u can Dream... U can do it

Hello everybody,
I'm a newcomer.
I intend to share my knowledge about chinese chess (or xiangqi), programmed for computers to play, especially in artificial intelligence domain. I've made a quite good program.
I wonder whether it is welcomed ot not.
I'm looking forward to hearing from you.

Welcome to CodeProject.

There are articles here at CodeProject covering a variety of subjects aimed at various levels of expertise. If you wish to share your expertise then an article is the way to go.

There are published guidelines here http://www.codeproject.com/info/submit.asp[^]

modified 1-Aug-19 21:02pm.

yuneiv wrote:
I wonder whether it is welcomed ot not.

Write an article about your program and offer it in the form of source code for people to look at. Take it from there Big Grin | :-D

"Real programmers just throw a bunch of 1s and 0s at the computer to see what sticks" - Pete O'Hanlon

Thank you, I think all I have to do now is spending time to prepare my very first acticle.
But could you show me a way to put a mass of over 4300 lines of code into an acticle and explaining hundreds of exciting points. It may take over a hundred pages. Suggest me a way to prune it off. Can I break it into several parts and show them one by one.
Help me. Thanks.

yuneiv wrote:
show me a way to put a mass of over 4300 lines of code into an acticle

You don't. You have your source and project in a zip file for people to download on the CP server.

yuneiv wrote:
explaining hundreds of exciting points

Look around at the general interest that people have around here, and just pick the top 3 to 5 pieces that might be really useful.

"Real programmers just throw a bunch of 1s and 0s at the computer to see what sticks" - Pete O'Hanlon

I've got it. Thanks.

yuneiv wrote:
But could you show me a way to put a mass of over 4300 lines of code into an acticle...

Assuming you are wanting the article's body to contain that much code, don't even go there. Supporting code should be in an attached (zip) file. You can certainly have code in the article's body, but it should be limited, and only to highlight important points, not just to take up room. You may lose a lot of potential readers when they are presented with pages full of code.

yuneiv wrote:
Can I break it into several parts and show them one by one.

Yes, several CP members have done just that for large subjects.

"Normal is getting dressed in clothes that you buy for work and driving through traffic in a car that you are still paying for, in order to get to the job you need to pay for the clothes and the car and the house you leave vacant all day so you can afford to live in it." - Ellen Goodman

"To have a respect for ourselves guides our morals; to have deference for others governs our manners." - Laurence Sterne

what is the method to print the nodes of a B-tree of any degree?
in preorder or postorder...

sushma

Sounds like homework, so no help here.

"Real programmers just throw a bunch of 1s and 0s at the computer to see what sticks" - Pete O'Hanlon