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I want to add a datum transformation, but I do not succeed

  • June 29, 2020
  • 5 replies
  • 48 views
J

Hello,

 

I want to add a cus datum transformation. But it is not working.

I have created this and saved in the shared folder:

 

DATUM_DEF Pulkovo1942\\

DESC_NM "Pulkovo 1942"\\

SOURCE "BP"\\

ELLIPSOID KRASSOW\\

 

XFORM_DEF WGS84_Pulkovo1942_Periplus_Test\\

DESC_NM "Pulkovo 1942, 7 parameter"\\

SRC_DTM WGS84\\

TRG_DTM Pulkovo1942\\

SOURCE "BP"\\

GROUP "PERIPLUS"\\

INVERSE Yes\\

MAX_ITR 8\\

METHOD 7PARAMETER\\

DELTA_X -686.10\\

DELTA_Y 123.50\\

DELTA_Z 574.4\\

ROT_X -8.0450\\

ROT_Y 23.366\\

ROT_Z -10.791\\

BWSCALE 2.926\\

 

COORDINATE_SYSTEM_DEF PULKOV1942_TM\\

GROUP "PERIPLUS"\\

DESC_NM "Pulkovo1942-PeriPlus"\\

SOURCE "BP"\\

DT_NAME Pulkovo1942\\

PROJ TMAF\\

UNIT METER\\

PARM1 09\\

SCL_RED 1.0\\

ORG_LAT 0\\

X_OFF 500000\\

Y_OFF 0\\

 

Please, can you help?

Best answer by daveatsafe

Hi @jjcdejong,

The seven parameters in the transformation are fine, but the coordinate system definition should have the projection set to TM, rather than TMAF. Please try changing this and re-running the conversion.

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5 replies

daveatsafe
Safer
Forum|alt.badge.img+20
  • daveatsafeSafer
  • Safer
  • June 29, 2020

Hi @jjcdejong,

The projection TMAF in your coordinate system is for transverse mercator plus an affine, which requires 7 parameters to be supplied. I think you want to use the TM projection, which only requires the single parameter for central meridian.

J
  • jjcdejong
  • Author
  • June 30, 2020

Hi, thanks for your reply. I do need to use these 7 parameters beacuse they vary slightly from the default values. And therfor the result is slightly different than required.

The problem is first that I do not see my coordinate system when I browse for them in FME.

And I am not sure if my definition as shown above is correct.

Thank for your help!

daveatsafe
Safer
Forum|alt.badge.img+20
  • daveatsafeSafer
  • Safer
  • Best Answer
  • June 30, 2020

Hi @jjcdejong,

The seven parameters in the transformation are fine, but the coordinate system definition should have the projection set to TM, rather than TMAF. Please try changing this and re-running the conversion.

J
  • jjcdejong
  • Author
  • July 1, 2020

Hi @jjcdejong,

The seven parameters in the transformation are fine, but the coordinate system definition should have the projection set to TM, rather than TMAF. Please try changing this and re-running the conversion.

I have changed my system definition. But it does not come up when I browse foor coordinate systems. Do you have any idea why this might be?

daveatsafe
Safer
Forum|alt.badge.img+20
  • daveatsafeSafer
  • Safer
  • July 2, 2020

I have changed my system definition. But it does not come up when I browse foor coordinate systems. Do you have any idea why this might be?

Please remove the '\\' from the end of the last line of the datum, transformation and coordinate system definitions. The '\\' is a line continuation character, to make each definition effectively a single line.

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