Google Groups no longer supports new Usenet posts or subscriptions. Historical content remains viewable.
Dismiss

Northing and Southing?

536 views
Skip to first unread message

HotRod

unread,
Aug 4, 2005, 2:26:01 PM8/4/05
to
I'm trying to get some code I wrote to be able to translate UTM Coordinates
into Latitude and Longitude, it currently works great for my area since I've
placed a lot of constants from an excel sheet I had but now I need to read
the information in from the .prj file. So my question is how do I use the
Northing and Easting Values. How do I adjust for this difference in the
Northing and Easting in each file? If anyone has Visual Basic I can post all
of the code.


The Values being read in are
Northing = 899219.938391579
Easting = 225915.338922908

In the .prj file that works for my area
False_Easting = 200000.0
False_Northing = 750000.0


In the file I'm trying to get to work here is the .prj file

PROJCS["NAD_1983_StatePlane_Massachusetts_Mainland_FIPS_2001",
GEOGCS["GCS_North_American_1983",
DATUM["D_North_American_1983",
SPHEROID["GRS_1980",6378137.0,298.257222101]],
PRIMEM["Greenwich",0.0],
UNIT["Degree",0.0174532925199433]],

PROJECTION["Lambert_Conformal_Conic"],
PARAMETER["False_Easting",200000.0],
PARAMETER["False_Northing",750000.0],
PARAMETER["Central_Meridian",-71.5],
PARAMETER["Standard_Parallel_1",41.71666666666667],
PARAMETER["Standard_Parallel_2",42.68333333333333],
PARAMETER["Latitude_Of_Origin",41.0],UNIT["Meter",1.0]]


vadivelan

unread,
Aug 9, 2005, 12:38:11 AM8/9/05
to
Hi,

Please check this site:
http://www.gpsy.com/gpsinfo/geotoutm/gantz/UTMConversions.cpp.txt

Here you will get the "c" source code for UTM to Lat-long and vice
versa, you can simply convert it to matlab codes. I hope this
information will help you.


P. Vadivelan
Chennai, India.
>

HotRod

unread,
Aug 9, 2005, 8:16:12 AM8/9/05
to
Thanks, I currently have a VB program that works but only when using the
"UTM NAD 83 Zone 17N" I'm trying to figure out how to adjust for Northing
and Easting. In my original code the Northing is set to 0 and the Easting is
set to 500000.0 , the new file I want to import has a Northing of 750000.0
and an Easting of 200000.0

So how do I adjust the numbers coming in? Do I add 750000 and 200000 to each
number?

"vadivelan" <vadive...@yahoo.co.in> wrote in message
news:1123562291.1...@g47g2000cwa.googlegroups.com...

jimirwin

unread,
Aug 9, 2005, 9:11:37 AM8/9/05
to
"HotRod" <NoS...@YourEmail.com> wrote in
news:11fh7ke...@corp.supernews.com:

> Thanks, I currently have a VB program that works but only when using
> the "UTM NAD 83 Zone 17N" I'm trying to figure out how to adjust for
> Northing and Easting. In my original code the Northing is set to 0 and
> the Easting is set to 500000.0 , the new file I want to import has a
> Northing of 750000.0 and an Easting of 200000.0
>
> So how do I adjust the numbers coming in? Do I add 750000 and 200000
> to each number?

From your original message, it looks like your data is not UTM, it is
Massachusetts State Plane Coordinates. Is this true? If so, then you need
to do an inverse Lambert Conformal Conic projection using the standard
parallels and origin of the Massachusetts SPC. Google for SPC conversion
programs.

Simply trying to adjust the northing and easting to convert to UTM isn't
going to work with any accuracy. The Mass SPC NAD83 northing (mainland
zone) is 750000 at latitude 41 degrees north, and the easting is 200000 at
longitude 71.5 degrees west. The UTM coordinates of that origin are y=
4541767.586 x=289736.758. So a crude (very crude, very inaccurate)
calculation to obtain UTM northings and eastings would be to add 3791767
to the northing and add 89736 to the eastings that you import.

The reason it is crude and inaccurate is that the two systems are based on
different projections, so the further away from N41 W71.5 your points are,
the worse the accuracy of your conversion.

--
Jim Irwin
http://www.holoscenes.com

HotRod

unread,
Aug 9, 2005, 2:28:30 PM8/9/05
to
Any idea what the following .prj file indicates? Also do you have any good
sources for the code that is used to do these conversions.

GEOGCS["GCS_North_American_1927",

DATUM["D_North_American_1927",

SPHEROID["Clarke_1866",6378206.4,294.9786982]],

PRIMEM["Greenwich",0],

UNIT["Degree",0.017453292519943295]]


Paul Cooper

unread,
Aug 9, 2005, 5:16:02 PM8/9/05
to
On Tue, 9 Aug 2005 14:28:30 -0400, "HotRod" <NoS...@YourEmail.com>
wrote:

Geographic coordinates expressed in degrees using the NAD27 Datum and
the Clarke ellipsoid.

HotRod

unread,
Aug 10, 2005, 8:09:19 AM8/10/05
to
Does that mean that they are not UTM?


"Paul Cooper" <a.paul....@NOntlworldSPAM.com> wrote in message
news:g77if15evmf2098gc...@4ax.com...

jimirwin

unread,
Aug 10, 2005, 8:23:17 AM8/10/05
to
"HotRod" <NoS...@YourEmail.com> wrote in
news:11fhtet...@corp.supernews.com:

> Any idea what the following .prj file indicates? Also do you have any
> good sources for the code that is used to do these conversions.
>

Google for map projection libraries. The PROJ4 software does almost any
kind of map projection conversion you can imagine. It has source in C.
There are many people who have created libraries for other languages.

Paul Cooper

unread,
Aug 10, 2005, 9:57:31 AM8/10/05
to
On Wed, 10 Aug 2005 08:09:19 -0400, "HotRod" <NoS...@YourEmail.com>
wrote:

>Does that mean that they are not UTM?
>

That's what I said. They should have X values between -180 and +180
and Y values between -90 and +90.

Paul

Pete Rissler

unread,
Aug 10, 2005, 12:02:08 PM8/10/05
to
They are in decimal degrees, latitude and longitude.

--
Pete Rissler
http://web1.greatbasin.net/~rissler/
http://www.tccycling.com

"HotRod" <NoS...@YourEmail.com> wrote in message
news:11fjrji...@corp.supernews.com...

HotRod

unread,
Aug 12, 2005, 11:04:59 AM8/12/05
to
This is an example of the numbers that are being read in

609689.75
205531.578125

Do you still think they are decimal degrees? Any idea how to convert them to
Latitude and Longitude?


0 new messages