[Proj] cs2cs: Gauss-Krüger to WGS84

[Andre Joost]

Am 10.12.12 12:09, schrieb Martin Trautmann:
> On 12-12-10 0:41, Jose Gonçalves wrote:

>> This use of cs2cs is not correct. You must run something like:
>>
>> cs2cs /string_for_system_1/ +to/string_for_system2/
>
> That's not what I did? I thought that
> 	+init=/usr/local/share/proj/world:gk4-d
> would be system1 and that
> 	+towgs84
> would include the system2 part.

No. +towgs84 is not the same as +to +init=epsg:4326
Using EPSG codes, the +towgs84 is hidden inside the code number.

>
>> echo 4491957.175 5511210.407 | cs2cs +init=epsg:31468 +to +init=epsg:4326
>> 11d53'13.028"E  49d44'14.871"N 48.659
>
> That's close enough to
>   11.88695229	49.73746425 (here)
>   11.88695	49.737475   (from a known opposite conversion)
>
> But what's the third part of the output line? I did not mind as long as
> it was 0.000, but I do not see it documented.

Thats the height above the ellipsoids surface. You can ignore it.

>
>> At least this point is in Germany... The datum transformation parameters
>> used are the following:
>> +towgs84=598.1,73.7,418.2,0.202,0.045,-2.455,6.7
>
> That's done automagically? Or do I have to apply this anywhere?
>

It is implemented in EPSG:31468 (if you have a current proj), but not in 
world:gk4-d.

For more precise values, you can look here:
<http://forum.openstreetmap.org/viewtopic.php?id=12723>



Greetings,
André Joost