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How to convert GPS coordinates to x,y,z

20 REPLIES 20
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Message 1 of 21
Anonymous
5173 Views, 20 Replies

How to convert GPS coordinates to x,y,z

How to convert GPS coordinates from degrees to x,y,z in km or miles. The
point looks like this (N56 43.827, W111 25.814, 1025') which is (North 56
deg and 43.827 min., West 111 deg and 25.814 min, 1025 feet).

Appreciate your answer or direction.

Jan
20 REPLIES 20
Message 2 of 21
Anonymous
in reply to: Anonymous

You might try searching the web for the keyword "transform" or
"transformation". That's what the GIS folks call that & I'm sure I've seen
free utilities for it. Sorry, not much help.

Jan Nademlejnsky wrote:

> How to convert GPS coordinates from degrees to x,y,z in km or miles. The
> point looks like this (N56 43.827, W111 25.814, 1025') which is (North 56
> deg and 43.827 min., West 111 deg and 25.814 min, 1025 feet).
>
> Appreciate your answer or direction.
>
> Jan
Message 3 of 21
Anonymous
in reply to: Anonymous

Change your angle units to Deg/Min/Sec and you can enter that information
directly.
Message 4 of 21
Anonymous
in reply to: Anonymous

Doh! those are just bearings. Greg has it.

"Greg McDowell, Jr" wrote:

> Change your angle units to Deg/Min/Sec and you can enter that information
> directly.
Message 5 of 21
Anonymous
in reply to: Anonymous

Greg,

How does that work? Don't you need to have a coordinate system set up in
Lat/Lon? Stand alone Acad doesn't allow for this, does it?

David
Message 6 of 21
Anonymous
in reply to: Anonymous

This is in vanilla AutoCAD. You don't need anything special.
Message 7 of 21
Anonymous
in reply to: Anonymous

Right, I am just curious as to how you insert an point who's x,y
location is based on latitude/longitude. I see in the units dialog box,
decimal, scientific, etc. but nothing even close to lat/lon.

David
Message 8 of 21
Anonymous
in reply to: Anonymous

if you go to www.cadalog.com , and go to their Civil Lisp routines, I
believe they have a couple of Lisp routines that can do that for you...


--
Alfred Narbaiz
Hugo Reed & Associates, Inc.
1601 Avenue N
Lubbock, TX 79401

anarbaiz@hugoreed.com

Dell Dimension 8100
1.3 Ghz Pentium IV
256Mb Ram
Windows 2000 Professional
ACAD 2000
Eagle Point 2001 Q2 1.3.2


"Jan Nademlejnsky" wrote in message
news:2209B17E63220801A94392AA55C15755@in.WebX.maYIadrTaRb...
> How to convert GPS coordinates from degrees to x,y,z in km or miles. The
> point looks like this (N56 43.827, W111 25.814, 1025') which is (North 56
> deg and 43.827 min., West 111 deg and 25.814 min, 1025 feet).
>
> Appreciate your answer or direction.
>
> Jan
>
>
>
>
Message 9 of 21
Anonymous
in reply to: Anonymous

I wasn't going to respond when I saw a bunch of other responses. But, after
reading them, I'm not so sure you are being pointed in the right direction.

The notation does NOT appear to be angles and distances as someone suggested,
but Lat, Long, Elevation. If this information is of any importance, I suggest
you seek a proffessional surveyor to aid you in converting this data.

Terry Scanlon


"Jan Nademlejnsky" wrote in message
news:2209B17E63220801A94392AA55C15755@in.WebX.maYIadrTaRb...
> How to convert GPS coordinates from degrees to x,y,z in km or miles. The
> point looks like this (N56 43.827, W111 25.814, 1025') which is (North 56
> deg and 43.827 min., West 111 deg and 25.814 min, 1025 feet).
>
> Appreciate your answer or direction.
>
> Jan
>
>
>
>
Message 10 of 21
Anonymous
in reply to: Anonymous

USGS has free software called Corpscon. It will convert lat/long to state
plane coords. You can download it from their website.

erik
"Greg McDowell, Jr" wrote in message
news:f06d7c2.1@WebX.maYIadrTaRb...
> Change your angle units to Deg/Min/Sec and you can enter that information
> directly.
>
>
Message 11 of 21
Anonymous
in reply to: Anonymous

The GPS coordinates are most likely based on the WGS 84 Datum (should
confirm), you will have to know which datum (eg. NAD83 or NAD27) and which
map projection (eg. UTM) you want to transform to.
Message 12 of 21
Anonymous
in reply to: Anonymous

Well, first you'll have to define the location of the 0,0,0-point that you
want to relate to! Basically, your GPS coordinates are relative equator
(0-latitude) and Greenwich (0-longitude) and normal sea level.

To convert your latitude reading is fairly easy, as one nautical mile equals
one latitude minute, meaning that your "X-coordinate" is 1.852 x 60 x (56 +
(43.827/60)) = 6303.887 km north of equator.

Your "Z-coordinate" is 1025 x 0.3048 = 312.42 m above normal sea level.

I don't know about your "Y-coordinate"; the distance between
longitude-meridians varies with latitude (they all end up in the same spot
at the poles, you know) 😉


Peter


"Jan Nademlejnsky" skrev i en meddelelse
news:2209B17E63220801A94392AA55C15755@in.WebX.maYIadrTaRb...
> How to convert GPS coordinates from degrees to x,y,z in km or miles. The
> point looks like this (N56 43.827, W111 25.814, 1025') which is (North 56
> deg and 43.827 min., West 111 deg and 25.814 min, 1025 feet).
>
> Appreciate your answer or direction.
>
> Jan
>
>
>
>
Message 13 of 21
Anonymous
in reply to: Anonymous

That's it! Thank you very much, Peter.

As far as I understand it, latitude, and longitude are angles measured from
the center of earth to its surface. What is the radius of the earth taken in
this calculation?
I guess I can go backward and recalculate it from your equation 1 mi = 1
min.

Jan


"Peter Blazejewicz" wrote in message
news:9D4E7186918CDF47C4CACB36370CCA35@in.WebX.maYIadrTaRb...
> Well, first you'll have to define the location of the 0,0,0-point that you
> want to relate to! Basically, your GPS coordinates are relative equator
> (0-latitude) and Greenwich (0-longitude) and normal sea level.
>
> To convert your latitude reading is fairly easy, as one nautical mile
equals
> one latitude minute, meaning that your "X-coordinate" is 1.852 x 60 x (56
+
> (43.827/60)) = 6303.887 km north of equator.
>
> Your "Z-coordinate" is 1025 x 0.3048 = 312.42 m above normal sea level.
>
> I don't know about your "Y-coordinate"; the distance between
> longitude-meridians varies with latitude (they all end up in the same spot
> at the poles, you know) 😉
>
>
> Peter
>
>
> "Jan Nademlejnsky" skrev i en meddelelse
> news:2209B17E63220801A94392AA55C15755@in.WebX.maYIadrTaRb...
> > How to convert GPS coordinates from degrees to x,y,z in km or miles. The
> > point looks like this (N56 43.827, W111 25.814, 1025') which is (North
56
> > deg and 43.827 min., West 111 deg and 25.814 min, 1025 feet).
> >
> > Appreciate your answer or direction.
> >
> > Jan
> >
> >
> >
> >
>
>
Message 14 of 21
Anonymous
in reply to: Anonymous

The US Army Corps of Engineers has programs to convert coordinates. You
have to be really careful as to which coordinate system you are converting
to. Depending on where you are on earth, you have a flat grid that
approximates the ellipsoid of earth, but this grid changes depending on
where you are. I would use a program if the coordinates have any sort of
importance.
Message 15 of 21
Anonymous
in reply to: Anonymous

Thank everyone for your responses. I should explain my reason for this
question. I finally managed to justify to my wife that we need GPS in our
lives. I bought Garmin eMap and I am very impressed with this technology.
There is one very nice feature which is possibilities to export the recorded
tracks into text or dxf file.

I mounted the GPS to my bike and my ultralight and I am recording my tracks.
Now I want to plot 3D path in Acad, just for fun. I can write a loop to draw
line from one point to the next, but I need to convert the angles of
latitude and longitude and elevation to actual coordinates in x, y, z. The
origin is not critical. I can always line it up with the existing map.

Jan


"Jod" wrote in message
news:FFC999D0C0A4C20729ECFD18C06A8F69@in.WebX.maYIadrTaRb...
> The US Army Corps of Engineers has programs to convert coordinates. You
> have to be really careful as to which coordinate system you are converting
> to. Depending on where you are on earth, you have a flat grid that
> approximates the ellipsoid of earth, but this grid changes depending on
> where you are. I would use a program if the coordinates have any sort of
> importance.
>
>
Message 16 of 21
Anonymous
in reply to: Anonymous

Ha ha ha, that's great. You know you will actually be converting FROM actual
coordinates to approximated flat coordinates. I want one too .

Jan Nademlejnsky wrote:

> ...I finally managed to justify to my wife that we need GPS in our
> lives....I mounted the GPS to my bike and my ultralight and I am recording my
> tracks.
> Now I want to plot 3D path in Acad, just for fun. I can write a loop to draw
> line from one point to the next, but I need to convert the angles of
> latitude and longitude and elevation to actual coordinates in x, y, z. The
> origin is not critical. I can always line it up with the existing map.
Message 17 of 21
Anonymous
in reply to: Anonymous

Jan,
Following your "angle-radius" theory will probably give you meaningless
values, as you'll have to assume that the globe is a perfect "ball", which
it isn't. For instance, the distance between the poles are less than the
diameter measured at equator. Easy to understand, if you think of the globe
as a soft ball, rotating around an axis through the poles; the centrifugal
force will force the "ball" into a "disk" shape, with the largest
circumference at equator (not the full, scientific explanation, I'm sure)!

Therefore, regarding the "radius", you can't go backwards, calculating from
the equation (1 nm = 1 min). But you can calculate the circumference,
measured over the poles, as 360 x 60 x 1.852 = 40003.2 km. But this is NOT
the same as the circumference around equator, or in any other angle away
from the rotational axis.

Also; note that the equation (1 nm = 1 min) is one NAUTICAL mile = one
LATITUDE minute. This relation is supposed to be exact, as one latitude
minute is simply the definition of a nautical mile.

1 nm = 1.852 km, and (according to my unit conversion program) = 1.150779
mile.

Still, this is no solution to your problem; I'll have to recommend - like
others here - that you find some kind of software for the purpose. Or, if
you only use your GPS within a limited aree, find some generic equations
that are nearly true in this area.

And now a little confession: Initially, after reading your first post
yesterday, I didn't notice that your longitude was WEST (habitual thinking,
as I normally work with northern latitudes / eastern longitudes), so I found
you to be located somewhere in a river valley north-east of Lake Bajkal in
Russia. And I simply couldn't figure out how a river located at an elevation
of 312 m could flow into a lake, located at an elevation of 445 m! Well, I'm
glad you're not there - and so should you be! 😉

regards
Peter


"Jan Nademlejnsky" skrev i en meddelelse
news:6A0CF5E52C0925FDEACD3CDBF36DC71D@in.WebX.maYIadrTaRb...
> That's it! Thank you very much, Peter.
>
> As far as I understand it, latitude, and longitude are angles measured
from
> the center of earth to its surface. What is the radius of the earth taken
in
> this calculation?
> I guess I can go backward and recalculate it from your equation 1 mi = 1
> min.
Message 18 of 21
Anonymous
in reply to: Anonymous

"David Renaud" wrote in message
news:3B654D42.8CE90B08@reiengineering.com...
> Right, I am just curious as to how you insert an point who's x,y
> location is based on latitude/longitude. I see in the units dialog box,
> decimal, scientific, etc. but nothing even close to lat/lon.
>
> David
Message 19 of 21
Anonymous
in reply to: Anonymous

are they local, state/provincial, national, polar or magnetic
"David Renaud" wrote in message
news:3B654D42.8CE90B08@reiengineering.com...
> Right, I am just curious as to how you insert an point who's x,y
> location is based on latitude/longitude. I see in the units dialog box,
> decimal, scientific, etc. but nothing even close to lat/lon.
>
> David
Message 20 of 21
Anonymous
in reply to: Anonymous

The real question here is projection -- we learned in school (and you
can try the experiment) that the skin of an orange won't spread out to
become a flat surface without tearing. There are hundreds of
projection systems, and a dozen or so in common use. Bottom line is
that there really isn't a way to go from lat/lon to cartesian
coordinatews without projecting them. The formulae are not hard, but
best use the one your map uses, or things won't work out.


"Jan Nademlejnsky" wrote:

>How to convert GPS coordinates from degrees to x,y,z in km or miles. The
>point looks like this (N56 43.827, W111 25.814, 1025') which is (North 56
>deg and 43.827 min., West 111 deg and 25.814 min, 1025 feet).
>
>Appreciate your answer or direction.
>
>Jan
>
>
>

Michael Porter Naval Architect / Boatbuilder
mporter at mp-marine dot com
Antispam -- make the obvious changes

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