[Proj] What is EPSG code for ST74 0 gon 65:0 projection.

Mikael Rittri Mikael.Rittri at carmenta.com
Thu Sep 8 15:39:48 EST 2011


Hello Mustafa.

There are two EPSG codes that are interesting, 3152 for ST74 and 3854 for County ST74.
 I think these two are nearly the same, but one may be a little more accurate. 
However, your problem is that both represent ST 74 0 gon 65:-1, to use the full Swedish name.
 There is a tradition (now deprecated by the Land Survey) to adapt the offsets (false easing and northing) for local use
so that 5-digit meter coordinates can be used inside a local 100 km square. The ending n:e of a Swedish CRS name means that
 the False Northing and False Easting are n and e multiplied by -100 000 m.  So the EPSG systems have FN = -6 500 000 m and FE = 100 000 m, but you need FN = -6 500 000 m and FE = 0 m.

 Well, that is not quite true; these round numbers are valid if you start with the true ST74 as the geodetic datum. In EPSG the datum is SWEREF99 (nearly WGS84) and the slightly modified projection parameters give a good approximation of the CRS in terms of SWEREF99.

So, ST74 0 gon 65:0 does not have an EPSG code. But take either EPSG:3854 or EPSG:3152,
 and decrease the False Easting by 100 000 m; that should be what you want. 

Best regards,

Mikael Rittri
Carmenta
Sweden
http://www.carmenta.com

8 sep 2011 kl. 16:21 skrev "Mustafa646" <noorcs22 at gmail.com>:

> I have a shapefile with projection ST74 0 gon 65:0 (represents Lidingö area
> in stockholm). What is the EPSG code for this projection ? I have searched
> and find that EPSG code for ST74 is 3152 but it did not work fully. I want
> to change this projection into EPSG:4326 by using ogr2ogr tool.  But when i
> convert from EPSG:3152 to EPSG:4326, i noted that shapefile does not fit on
> correct location (Lidingö). Instead It placed near Eskilstuna. (A place
> approx 100 km away from stockholm).
> 
> Its bounding box values were 16.398, 59.353 (for Eskilstuna area), when
> converted from 3152 to 4326.
> but actually, the bounding box values for Lidingö should be 18.345, 59.234
> (for Lidingö area)
> 
> Is there any way to solve this problem ?
> 
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