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Romanian Stereo70 projection problems

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#1
bebe onea

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Hello again,
I've got the following problem. I've got some topographic maps from Romania with Stereo70 projection (Romanian cartographic projection) and try to georeferenciate them but after I set the projection and add control points the map is not where it is supposed to be.
The characteristics of the projection are as follows:
* Stereo 70 ("stereo şaptezeci")
o "Hristow" Oblique Stereographic, units are meters
o Ф0 = 46? North and λ0 = 25? East of Greenwich
o False Easting = False Northing = 500 000 m
o m0 = 0.999750
o uses the "Dealul Piscului 1970" Datum (Krassowsky 1940 ellipsoid)
Can anyone help, please?
Thanks.

#2
mbutcher

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Hi all,

I am currently trying to write a scipt for the MapInfo.prj file to create a coordinate system for the "Romania National Grid (Stereo 70)"

The information I have been provided with is;

Stereo 70 ("stereo şaptezeci")
"Hristow" Oblique Stereographic, units are meters Ф0 = 46° North and λ0 = 25° East of Greenwich False Easting = False Northing = 500 km m0 = 0.999750 uses the "Dealul Piscului 1970" Datum (Krassowsky 1940 ellipsoid)

My efforts to date is below, but I keep getting a Error message, 'Invalid distance units: 25.'

"--- Romania National Grid (Stereo 70) ---"
"Dealul_Piscului_1970", 7, 25, 46, 0.99975, 500000.0, 500000.0

If anybody could please shed some light I would very much appreciate it. Thanks


Yours,
Mark.

#3
gregsd

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Hi Mark,

No luck on MUGUKI forum!

If you haven’t already then have a look at Appendix H & I in the MapInfo User Guide, as they cover creating your own coordinate system and custom datum.

From the little I know I think the issue you’ll have is that the "Dealul Piscului 1970" datum isn’t defined, or at least it’s not listed in the Appendix. So, you can’t create your own custom coordinate system without this. However, the Krassowsky ellipsoid is listed, so you could define your own datum and then use this to create the coordinate system in the MAPINFOW.PRJ file.

I’d also try and post something on the MAPINFO-L Google groups list as I know there are few members from Central Europe, so they may well be able to help further.

Regards


Greg Driver

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#4
mbutcher

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[quote name='gregsd' date='Apr 29 2008, 07:52 AM' post='17455']
Hi there,

Nothing conclusive back from MUGUKI or MapInfo themselves.

I think the problem is that MapInfo does not support an Oblique Stereographic Projection, but will wait to hear back. Otherwise will try rewriting the .prj file for the Krassowsky ellipsoid I think.

I will try the 'MAPINFO-L Google groups list' though thanks.

Regards.

#5
mbutcher

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Hi bebe onea,

I have posted the same problem, and my efforts so far have come up with this. Did you get any further?

I am currently trying to write a scipt for the MapInfo.prj file to create a coordinate system for the "Romania National Grid (Stereo 70)"

The information I have been provided with is;

Stereo 70 ("stereo şaptezeci")
"Hristow" Oblique Stereographic, units are meters Ф0 = 46° North and λ0 = 25° East of Greenwich False Easting = False Northing = 500 km m0 = 0.999750 uses the "Dealul Piscului 1970" Datum (Krassowsky 1940 ellipsoid)

My efforts to date is below, but I keep getting a Error message, Invalid distance units: 25.

"--- Romania National Grid (Stereo 70) ---"
"Dealul_Piscului_1970", 7, 25, 46, 0.99975, 500000.0, 500000.0

If anybody could please shed some light I would very much appreciate it. Thanks

#6
gregsd

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Hi Mark,

I've done a bit more digging around and I've found the datum parameters which you'll need to define a custom datum (see Appendix I) -

Datum Name Ellipsoid Name -DEALUL PISCULUI 1970 Krassovsky
dX (m) = 28.00
dY (m) = -121.00
dZ (m) = -77.00
rX (as) = N/A
rY (as) = N/A
rZ (as) = N/A
Scale (x 10^-6) = N/A

I found these here.

That just leaves the whether MapInfo supports the Oblique Sterographic projection? If it does then you should have enough information to define a custom coordinate system.

HTH


Greg Driver

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#7
Hans van der Maarel

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#8
gregsd

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Mark,

This is a custom coordinates system based on the Sterographic projection (not sure if this is the same as Oblique Sterographic?):

“Romania National Grid (Stereo 70)”, 20, 999, 3, 28.00,-121.00, -77.00, 7, 25, 46, 0.999750, 500000, 500000

where-
20 = Projection -Sterographic
999, 3, 28.00,-121.00, -77.00 = 999 is a custom datum based on the parameters above
7 = coordinate units metres
25 = Origin long 25 deg
46 = Origin lat 46 deg
0.999750 = scale factor
500000 = false easting in metres
500000 = false northing in metres

I've added this the MapInfow.PRJ file and it doesn't throw an error but whether it's right or not I can't tell!


Greg Driver

GIS Analyst
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