[Proj] Understanding 2D Helmert

[Even Rouault]

On vendredi 26 octobre 2018 19:54:22 CEST Andre Joost wrote:
> Am 26.10.18 um 17:37 schrieb Even Rouault:
> > On vendredi 26 octobre 2018 14:40:17 CEST Kristian Evers wrote:
> >> If that is the case it should just be a matter of changing the
> >> type of the output units internally in the operation. If you
> >> submit a new ticket on the github page with a short description
> >> I'll take a look at it within the next couple of days.
> > 
> > Things are fine. This is just that using 'proj' for such operation is
> > inapproprate. You should use the new 'cct' binary.
> 
> Thanks, that worked for me in this way:
> 
> cct -z 0 +proj=helmert +convention=coordinate_frame +x=239228.435
> +y=6693404.951 +s=1.0003267 +theta=18795.4443 <HelmertIn.txt
> 
>  >>HelmertOut.txt
> 

> Maybe this example should be added to the Helmert and/or cct man pages.
> 

Where do those figures come from ? Is it some official transformation 
registered somewhere ?

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