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

[alexander at isacson.info]

Thank you for your quick reply.

I have two further questions:
  My GPS reciver outputs degrees and not degrees, minutes, seconds. Can
cs2cs handle that? Can I just do "echo 58.39693 15.51353 | cs2cs ...."?

The accuracy of 10-15 centimeters is good enough for my application. It
won't be used for navigation just orientation and displayed on a screen.
Do I need to adjust the parameters if I want the best accuracy to be
around Norrköping (about 58d30m30s 16d10m)

Thanks again.

Regards
/Alexander

> 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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