GPS - Convert from NAD83 to UTM

Author

Convert from NAD83 to UTM

Stephen Clark

2007-01-30, 3:33 pm

I would like to convert 3,000 Lat and Long values I have for North American
(USA) county centroids to UTM Easting and Northings. I have tried to use the
workbook at the bottom of:

http://www.uwgb.edu/dutchs/UsefulData/UTMFormulas.HTM

I select the correct DATUM (NAD83) on the "Main Page" but the converted
values on sheet "Batch Convert Lat Long To UTM", column AE and AF are not
correct (an XY plot of them does not look like the USA). As an example the
Easting and Northings for Alabama and Washington state are problematic -
they have overlapping Eastings which can't be right! Is the Long Zone output
important?

Thanks.

Eino Uikkanen

2007-01-30, 3:33 pm

"Stephen Clark" <stephenclark@clara.co.uk> kirjoitti
viestissä:1170183327
.1405.0@proxy02.news.clara.net...
>I would like to convert 3,000 Lat and Long values I have for North American
>(USA) county centroids to UTM Easting and Northings. I have tried to use
>the workbook at the bottom of:
>
> http://www.uwgb.edu/dutchs/UsefulData/UTMFormulas.HTM
>
> I select the correct DATUM (NAD83) on the "Main Page" but the converted
> values on sheet "Batch Convert Lat Long To UTM", column AE and AF are not
> correct (an XY plot of them does not look like the USA). As an example the
> Easting and Northings for Alabama and Washington state are problematic -
> they have overlapping Eastings which can't be right! Is the Long Zone
> output important?
>
> Thanks.
>

If you fail to successfully convert the coordinates using the methods you
are trying now, you could try GeoConv:

http://www.kolumbus.fi/eino.uikkane...onvgb/index.htm

Eino Uikkanen
http://www.kolumbus.fi/eino.uikkanen/gb/index.htm

skmort@lanset.com

2007-01-30, 10:33 pm

On Jan 30, 10:55 am, "Stephen Clark" <stephencl...@clara.co.uk> wrote:
> I would like to convert 3,000 Lat and Long values I have for North American
> (USA) county centroids to UTM Easting and Northings. I have tried to use the
> workbook at the bottom of:
>
> http://www.uwgb.edu/dutchs/UsefulData/UTMFormulas.HTM
>
> I select the correct DATUM (NAD83) on the "Main Page" but the converted
> values on sheet "Batch Convert Lat Long To UTM", column AE and AF are not
> correct (an XY plot of them does not look like the USA). As an example the
> Easting and Northings for Alabama and Washington state are problematic -
> they have overlapping Eastings which can't be right! Is the Long Zone output
> important?
>
> Thanks.

There are 60 zones around the planet,, the only way to know which
easting point you are at is from the zone information! Each zone is
6 degrees wide at the equator! Zone one starts at Longitude 180,
zone 2 starts at 174W.

The center UTM grid (E500,000) of each zone is in perfect alignment
(north and south) with that corresponding longitude, which for zone
one would be 177W. For zone 10 here in California it would be
123W. As you go N or S on any other UTM grid line, the Long. will
drift to the East or West depending on which side of the UTM E500,000
(center Long.) you are at!

As you go north or south, since the UTM grids do not compensate for
the curvature of the earth, there will be points near the edge of the
zones where they will fall into two different zones! When you
convert from Lat/Long at those overlapping points you should get a UTM
point for both zones! (another one of the "beasts" of UTM) I
haven't had the opportunity to take my GPS into one of those areas to
see how my GPS handles the duel info??????
example: Lat N40:00:00 W120:00:00 NAD83
will give N4432069.037 E756099.648 Zone 10
and N4432069.037 E243900.352 Zone 11
they are the same geographic point
BTW, I almost always work with UTM when I am out hiking!!!!
SKM

Mississippi Dan

2007-01-30, 10:33 pm

"Stephen Clark" <stephenclark@clara.co.uk> wrote in message
news:1170183327.1405.0@proxy02.news.clara.net...
>I would like to convert 3,000 Lat and Long values I have
>for North American (USA) county centroids to UTM Easting
>and Northings. I have tried to use the workbook at the
>bottom of:
>
> http://www.uwgb.edu/dutchs/UsefulData/UTMFormulas.HTM
>
> I select the correct DATUM (NAD83) on the "Main Page" but
> the converted values on sheet "Batch Convert Lat Long To
> UTM", column AE and AF are not correct (an XY plot of them
> does not look like the USA). As an example the Easting and
> Northings for Alabama and Washington state are
> problematic - they have overlapping Eastings which can't
> be right! Is the Long Zone output important?
>
The workbook conversion may be okay. I use either Corpscon
or GEOTRANS for batch conversions. Corpscon is from the US
Corps of Engineers. GEOTRANS can be downloaded from
http://earth-info.nga.mil/GandG/geotrans/index.html

The lower 48 states are divided into 10 UTM zones.
http://rockyweb.cr.usgs.gov/outreac...Zones_USA48.jpg

A point in each zone could have the exact same
easting/northing coordinates. Only the zone number keeps
them separate. Simple xy plots can't plot these in their
correct geographic position. Lat-long (decimal degrees) is
the easiest way to plot points over a large area spanning
several UTM zones.

Best,
Dan

Jerry

2007-01-31, 10:33 am

On Jan 30, 12:55 pm, "Stephen Clark" <stephencl...@clara.co.uk> wrote:
> I would like to convert 3,000 Lat and Long values I have for North American
> (USA) county centroids to UTM Easting and Northings. I have tried to use the
> workbook at the bottom of:
>
> http://www.uwgb.edu/dutchs/UsefulData/UTMFormulas.HTM
>
> I select the correct DATUM (NAD83) on the "Main Page" but the converted
> values on sheet "Batch Convert Lat Long To UTM", column AE and AF are not
> correct (an XY plot of them does not look like the USA). As an example the
> Easting and Northings for Alabama and Washington state are problematic -
> they have overlapping Eastings which can't be right! Is the Long Zone output
> important?
>
> Thanks.

Stephen:
SKM and Dan have already explained why UTM is not suitable for your
purposes. Use the Lat/Long in decimal degrees to plot the points.
Remember that west longitude is a negative number.

Jerry

Stephen Clark

2007-01-31, 12:33 pm

Hi ALL, thanks for you help which has been really useful and interesting.
Following the advice given here I have added 500,000m multiplied by the
longitude zone (a number, 2 in Maine to 10 in Washington/California) to the
Eastings I have, and it looks OK. No sign yet of any overlap. I have not
needed to do any such modification with the Northing.

The reason I need E & N's is that I have some modelling software that works
only with a grid.

Once again, thanks for your help and encouragemnet.

skmort@lanset.com

2007-01-31, 3:33 pm

On Jan 31, 8:42 am, "Stephen Clark" <stephencl...@clara.co.uk> wrote:
> Hi ALL, thanks for you help which has been really useful and interesting.
> Following the advice given here I have added 500,000m multiplied by the
> longitude zone (a number, 2 in Maine to 10 in Washington/California) to the
> Eastings I have, and it looks OK. No sign yet of any overlap. I have not
> needed to do any such modification with the Northing.
>
> The reason I need E & N's is that I have some modelling software that works
> only with a grid.
>
> Once again, thanks for your help and encouragemnet.

HERE IS A BIG OOPs
I hate to be a party pooper, but even at the equator the 500,000 is a
false number!!!!!
IT OVER-LAPS!!!!! They gave the center grid a false # big enough so
that they would never have to deal with negative numbers!!!! So, I
think your east west grid is going to be elongated by at least twice
the over-lap (about 2 times 166021.443 meters,, even more the further
you get from the equator) for each zone you cross?????? In other
words you may have to find the over-lap distance relative to each
different latitude point and subtract that out to find the relative
distance in an other zone for each zone you cross?????? There may be
an easier way, but these are some ideas you need to keep in
mind????? It is another bucket of worms if you live south of the
equator because the northing is given a big false number,,, here in
the north, the northing is a direct reading from the equator,,,
(notice the second example below),,, all 4 UTM points below, are
the same geographic location!!!!!
North at the equator over-lap example:
For lat N000000.000 and long W1200000.000 NAD83
returns N0.000 E833978.557 Zone 10
and N0.000 E166021.443 Zone 11
South of equator over-lap example:
For lat S000000.000 and Long W1200000.000 NAD83
returns N10000000.000 E833978.557 Zone 10
and N10000000.000 E166021.443 Zone 11
SKM

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