I may be going at this problem the complete incorrect way, I just need some guidance is all. I need to perform a helmert transformation on lat/long to convert to a users local grid system that they create with multiple points like the one I posted below

Lets say I want to make a pjt or wkt string with proj for a helmert transformation. (https://proj.org/operations/transformations/helmert.html)

I have no clue how to build a string like this

proj=helmert convention=coordinate_frame x=-9597.3572 y=.6112 s=0.304794780637 theta=-1.244048

from information like this:

<record id="Point 1" >
<value name="Lat" value="redacted"></value>
<value name="Lon" value="redacted"></value>
<value name="Ellipsoid_Elv" value="20.1497127691777"></value>
<value name="Local_X" value="883498.7601626500300"></value>
<value name="Local_Y" value="93747.3358902813200"></value>
<value name="Local_Z" value="152.2231851663858"></value>
<value name="HRMS" value="0.019685"></value>
<value name="VRMS" value="0.03937"></value>
<value name="Use_Horizontal" value="No"></value>
<value name="Use_Vertical" value="No"></value>
<value name="Description" value="1050"></value>

And I have multiple points, records just like the one above, so i need to be able to account for multiple points too. Any information or anyone that can point me in the direction please say something.

  • That type of transformation was not Helmert's intention (one of his conditions is that the rotation angles are very small), so some terms of the transformation were simplified. Although PROJ has a parameter not to use the simplified function, it is much more convenient to apply an Affine transformation in 3D. Aug 7 at 4:28

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