Hungarian EOV Projection

[Schalk van Lill]

Dear group

Sorry, a little bit long-winded but hopefully it will explain all.

I have a set of points which is said to be in the Hungarian EOV projection. These points were converted to Lat/Long WGS 84 using the Save as command in MapInfo. The file was then exported as a .mif and imported into GPS Trackmaker and uploaded to the Garmin GPS. We have done this loads of times in the past and has never been a problem. However, when trying to find these points in the field, we could not.  After checking a known point it transpired that the coordinates we have for the points are correct but they plot about 200m East from where the point is located in the field. However, when typing the location of the point manually into the GPS, the location is exactly as it is in the field. 

I then  investigated the issue further. The Hungarian EOV as defined in MapInfo 2011 is:

"Hungarian Projection System (EOV)", 8, 1004, 7, 19.04857178, 47.14439372, 0.99993, 650000, 200000

This seems to be incorrect as the parameters I found on spatialreference.org is:

PROJCS["HD72EOV",

GEOGCS["HD72",

DATUM["D_Hungarian_1972",

SPHEROID["GRS_1967",6378160,298.247167427]],

PRIMEM["Greenwich",0],

UNIT["Degree",0.017453292519943295]],

PROJECTION["Hotine_Oblique_Mercator_Azimuth_Center"],

PARAMETER["latitude_of_center",47.14439372222222],

PARAMETER["longitude_of_center",19.04857177777778],

PARAMETER["azimuth",90],

PARAMETER["rectified_grid_angle",90],

PARAMETER["scale_factor",0.99993],

PARAMETER["false_easting",650000],

PARAMETER["false_northing",200000],

UNIT["Meter",1]]

So I then created the entry for the EOV Projection in the prj file as: 

"MY Hungarian Projection System (EOV)", 7, 1004, 7, 19.04857178, 47.14439372, 90, 0.99993, 650000, 200000

However when I try and convert from this to Lat/Long WGS 84, MapInfo seems to rotate all 90 degrees and totally erroneous coordinates. 

So I must have done something wrong. Any ideas?

Cheers

Schalk

[Uffe Kousgaard]

How did you do it in the past? What is different? If it was with a
different version of MapInfo, try to look at the parameters for your
projection in that older version.

Regards
Uffe Kousgaard

Schalk van Lill wrote:
> Dear group

[Schalk van Lill]

Hi Uffe

Sorry. Didn't explain that well. We have used this methodology of
getting data from MapInfo into the GPS numerous times for other
countries in Europe and Africa, but it is the first time we are doing
it in Hungary. Also the first time we are doing it in Hungarian EOV.
The previous version of MapInfo (10.5) had the False Easting and False
Northing mixed up ("Hungarian Projection System (EOV)", 8, 1004, 7,
19.04857178, 47.14439372,
0.99993, 200000, 650000). Apart from that everything is the same as
the previous version.

Regards
Schalk

[Ahmet DABANLI]

Hi,
First, You have inserted the 90 value in a wrong place
Second, MapInfo does make On the fly coord transformation, but does
not make on the fly datum conversion

we had may times problems with this
This is an example for datum conversion matris parameters
"GK Central Meridian 27 (WGS84)", 8, 9999, 4, -84.003, -102.315,
-129.879, -0.0183, 0.0003, -0.4738, 1.0347, 0, 7, 27, 0, 1, 500000, 0

Before this, we had ~9 meter difference btw ED50 and WGS84 and 180 m
btw ITRF and WGS84

You should find the transformation parameters for your projction to WGS84

best regards

On Tue, Aug 9, 2011 at 11:54 AM, Schalk van Lill
<schalk....@gmail.com> wrote:
> Dear group
> Sorry, a little bit long-winded but hopefully it will explain all.
> I have a set of points which is said to be in the Hungarian EOV projection.
> These points were converted to Lat/Long WGS 84 using the Save as command in
> MapInfo. The file was then exported as a .mif and imported into GPS
> Trackmaker and uploaded to the Garmin GPS. We have done this loads of times
> in the past and has never been a problem. However, when trying to find these
> points in the field, we could not.  After checking a known point it
> transpired that the coordinates we have for the points are correct but they
> plot about 200m East from where the point is located in the field. However,
> when typing the location of the point manually into the GPS, the location is
> exactly as it is in the field.
> I then  investigated the issue further. The Hungarian EOV as defined in
> MapInfo 2011 is:

> "Hungarian Projection System (EOV)", 8, 1004, 7, 19.04857177777778, 47.14439372,

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--
Ahmet DABANLI

[Schalk van Lill]

Hi Ahmet

Great advice. I got to within ~7m now, which puts me in the ballpark.
I did have to change the projection type back to 8 and get rid of the
90.

Any idea where the 90 must be as I put it in as per the helpfile
(copied below with my parameter added):

The parameters of a coordinate system are (in this order):
Coordinate System Name: "MY Hungarian Projection System (EOV)"
Projection Type: 7
Datum: 9999, 21, 56, -75.77, -15.31, 0.37, 0.2, 0.21, 1.01, 0
Units: 7
Original Longitude: 19.04857178
Original Latitude: 47.14439372
Standard Parallel 1: Not used for this projection type
Standard Parallel 2: Not used for this projection type
Azimuth: 90
Scale Factor: 0.99993
False Easting: 650000
False Northing: 200000
Range: Not used for this projection type

Regards
Schalk

[Ahmet DABANLI]

Dear Schalk
with repect to my understanding
your parameters should be like

"MY Hungarian Projection System (EOV)",7,9999,21, 56, -75.77,
-15.31, 0.37, 0.2, 0.21, 1.01, 0,7,19.04857178,
47.14439372,0.99993, 200000, 650000

and no need to put 90
Best regards

[Schalk van Lill]

Hi Ahmet

Thanks, yes, I tried that, but the projection type needs the 90, else
everything ends up in a straight line.
When importing a mif using the parameters without the 90 in it, it
actually gives me an error of "too few parameters for this projection
type". So - something screwy.

Anyway, thanks for all your help.

Cheers
Schalk

[Jaromir]

Hi,

I discovered that the definition of EOV in mapinfo is wrong, the last
2 parameters are exchanged. The right definition should be:

"Hungarian Projection System (EOV)\p23700", 8, 1004, 7, 19.04857178,
47.14439372, 0.99993, 650000, 200000

Jaromir

On 11. Aug, 15:04 h., Schalk van Lill <schalk.vanl...@gmail.com>

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