[OSRS-PROJ] Converting from WGS-84 to Sweden's RT-90

[Paul Kelly]

Hello

On Mon, 9 Feb 2004, Alexander Isacson wrote:

> Hello list.
>
> I'm looking for a way to transform coordinates (WGS-84 lat, long) from a
> GPS receiver to RT-90 (N/E) which is local grid here in Sweden. I'm
> really new to all this and I'm just realizing that these transformations
> are allot harder than I thought. Hopefully PROJ.4 can help me out.
>
> To go form WGS-84 to RT-90 one has to preform the seven-parameter
> translation. http://www.geocities.com/mapref/prj/se/se.html
>
> How do I preform this transformation? Can it be done with cs2cs? Is
> there a +fromwgs84 parameter?

I found a 7-parameter transformation at this website:
http://crs.ifag.de/country_select.php?country=SE

The following command line gives OK results but they are some 10-15cm out
from the test point at
http://www.geocities.com/mapref/prj/se/se_rt90simp.html and I don't know
what's causing that. You should maybe try with some other software to
verify proj.4's result. The problem may simply be the small error
resulting from treating SWEREF93 and WGS84 as the same thing (they are
close enough for many purposes).

echo 18d7\'29.50084\" 66d19\'4.85672\" | \
cs2cs +proj=longlat +datum=WGS84 +to +proj=tmerc +lat_0=0 \
+lon_0=15d48\'29.8\" +x_0=1500000 +k_0=1 +ellps=bessel \
+towgs84=414.1,41.3,603.1,-0.855,2.141,-7.023,0
1604007.49      7359600.91 -31.26


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