[Proj] Re: Proj Digest, Vol 42, Issue 8

[Roger Oberholtzer]

On Fri, 2007-11-30 at 11:47 +0100, Jordi Gilabert Vall wrote:
> I use these 7 coefficients with cartography in Catalonia (Spain), with
> right results:
> 
> cs2cs +proj=latlong +datum=WGS84 +ellps=WGS84 +to +init=epsg:23031
> +proj=utm +ellps=intl +zone=31 +units=m +towgs84=-
> 131.0320,-100.2510,-163.3540,1.2438,0.0195,1.1436,9.3900

I have finally had a chance to check this. Sorry it took so long. I do
not get much difference. Could you give me a few sample lat/longs and
the northings/eastings you get with this command? I did have to change
the zone to 30 for Madrid for my tests, os the derived values were very
far off.

> 
> 
> More information:
> 
> http://www.euref-iag.net/symposia/book2003/4-6.pdf
> 
> http://www.fomento.es/NR/rdonlyres/8B4D8323-5706-4F8F-84F7-C89774DCC2A1/29826/hercam.pdf
> 
> 
> Jordi Gilabert Vall
> 
>         ---------------------------------------------------------------------- 
>         
>         Message: 1
>         Date: Thu, 29 Nov 2007 14:55:17 +0100
>         From: Roger Oberholtzer <roger at opq.se>
>         Subject: RE: [Proj] WGS84 to ED50
>         To: "PROJ.4 and general Projections Discussions" 
>                 <proj at lists.maptools.org>
>         Message-ID: <1196344518.25474.84.camel at acme.pacific>
>         Content-Type: text/plain; charset=UTF-8 
>         
>         I have a bit more information on the problem with WGS84
>         lat/longs ->
>         ED50(Spain) northings and eastings.
>         
>         The software that is being used does not have a 'Spanish'
>         setting. So
>         they have defined an ED50 7 parameter transform, with these 
>         coefficients:
>         
>         
>         > International Ellipsoid 1924 definition
>         > Mayor semiaxle: 6378388
>         > Minor semiaxle:6356911,9461
>         > 1/f:297
>         > Excentricity: 0.0819910890032286
>         >
>         > About the 7 parameters transformation 
>         > Translation X (m): 125.098545
>         > Translation Y (m): 76.000054
>         > Translation Z (m): 156.198703
>         > X Rotation(seconds): 0
>         > Y Rotation(seconds): 0
>         > Z Rotation(seconds): -1.129
>         > Scale factor (ppm): - 8.30463103
>         >
>         > This correspond with applanix header file saying
>         > Mapping frame datum: ED50_ESPAÑA ; a = 6378388.000000; 1/f =
>         297.000000;
>         >  Coordinate transformation from WGS84 to mapping frame
>         datum 
>         >     dX = 125.098545; dY = 76.000054; dZ = 156.198703; f =
>         0.999991695369;
>         >     R1 = 0.000000000000; R2 = 0.000000000000; R3 =
>         -0.000005473550;
>         >  sequence of the rotations: x,y,z,1
>         >  Mapping frame projection : TM; 
>         >  central meridian = -3.000000 deg;
>         >  latitude of the grid origin = 0.000000 deg; grid scale
>         factor = 0.999600:
>         >  false easting = 500000.000000 m; false northing = 0.000000
>         m;
>         >
>         >
>         > Where Rotations are in radians 
>         
>         I have tried setting proj to use this, as reported earlier in
>         this thread, with no luck. I tried using the 7 parameters as
>         +towgs84=125.098545,76.000054,156.198703,0.0,0.0,-1.129,-8.30463103, but that made things worse. 
>         
>         fromProj = pj_init_plus(
>                                 "+proj=latlong "
>                                 "+ellps=WGS84 "
>                                 "+no_defs");
>         
>         toProj = pj_init_plus(
>                                 "+proj=utm "
>                                 "+ellps=intl "
>                                 "+k=0.999600 "
>                                 "+x_0=500000.0 "
>                                 "+y_0= 0.0 "
>                                 "+zone=30 "
>                                 "+units=m"
>         
>         "+towgs84=125.098545,76.000054,156.198703,0.0,0.0,-1.129,-8.30463103"
>                                 "+no_defs"); 
>         
>         So I am guessing I cannot simply use the 7 parameters as
>         given. Correct?
>         
>         
>         
>         --
>         Roger Oberholtzer
>         
>         OPQ Systems / Ramböll RST
>         
>         Ramböll Sverige AB
>         Kapellgränd 7
>         P.O. Box 4205
>         SE-102 65 Stockholm, Sweden 
>         
>         Office: Int +46 8-615 60 20
>         Mobile: Int +46 70-815 1696
>         
>         
>         
>         ------------------------------
> 
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-- 
Roger Oberholtzer

OPQ Systems / Ramböll RST

Ramböll Sverige AB
Kapellgränd 7
P.O. Box 4205
SE-102 65 Stockholm, Sweden

Office: Int +46 8-615 60 20
Mobile: Int +46 70-815 1696