SV: [OSRS-PROJ] ED50 Denmark

[Torben Bach]

Hi Paul

THANKS !!! I was using proj4 directly, not the cs2cs program. The
ellipsoid used is actually WGS84, but entering this into your golden
command line fixes my problem. If your currious heres what I get from my
comparison:


In-put coordinate:  10.138618  56.342032

Outputs:

MapInfo  : 570466.57247057 6244935.6590597    (According to MapInfo they
have an error)
KMS Trans: 570464.297      6244936.971        (Official Danish program
Thingy :-) )
cs2cs    : 570464.18       6244937.01	    (Pauls Golden Line)

PERFECT !

Thanks a lot !!

Best regards,

-Torben

The commandline used:
cs2cs +proj=latlong +ellps=WGS84 +towgs84=0,0,0 +to +proj=utm +zone=32
+ellps=intl +towgs84=-81.1,-89.4,-115.8,0.485,0.024,0.413,-0.54





-----Oprindelig meddelelse-----
Fra: Paul Kelly [mailto:paul-grass at stjohnspoint.co.uk] 
Sendt: 24 October 2003 09:59
Til: Torben Bach
Emne: Re: [OSRS-PROJ] ED50 Denmark


On Thu, 23 Oct 2003, Torben Bach wrote:

> Hi
>
> Completely new to the subject I have been roaming the internet trying 
> to find a "golden" command line to proj4 for converting lat-lon 
> coordinates to DANISH ED50 UTM zone 32N. Apparently the internal ED50 
> is not the same as the Danish (or german or french...) ED50 - im am 
> confused - does anybody know the "golden" command line I so badly long

> for ?

You don't say which ellipsoid your latitude/longitude co-ordinates refer
to. Seeing you mention EUREF89 in the next paragraph I will assume it is
the GRS80... according to
http://crs.ifag.de/country_select.php?country=DK
then your command line with datum transformation parameters would be
something a bit like

cs2cs +proj=latlong +ellps=GRS80 +towgs84=0,0,0 +to +proj=utm +zone=32 \
+ellps=intl +towgs84=-81.1,-89.4,-115.8,0.485,0.024,0.413,-0.54

(Actually these parameters are in GRASS if you go to set up a Denmark
location.)

Does this work?

>
> Another question - how accurate is the ouput from Proj4 ? I have 
> compared results converting to EUREF89 with output from programs from 
> the national Ministry of the Environment (KMS at www.kms.dk) handling 
> this stuf and MapInfo, and they gave the same results within a meter 
> or so. But using ED50 and Proj4 gave coordinates lying hundreds of 
> meters from MapInfo and "official" KMS results (this was how I 
> discoverd I needed the "golden" command line).

As hinted above you don't say which ellipsoid your lat-long co-ordinates
are on but presumably it is not ED50 and therefore you need datum
transformation parameters.

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