[Proj] Understanding 2D Helmert

Even Rouault even.rouault at spatialys.com
Fri Oct 26 10:37:32 EST 2018

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.

'proj' is just for plain-old projection methods that take long, lat as input, 
whereas here input coordinates are in the projected space

echo 1000 0 0 | cct +proj=helmert +convention=coordinate_frame +theta=-162000

     707.1068       707.1068        0.0000           inf

(162000 arc-second = 45 deg)

(due to a current oddity of cct, you need to specify 3D coordinates, or add "-
z 0" in the parameters )

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