[Qgis-user] How to calculate the transformation parameters for the QGIS Affine Plugin

[Siki Zoltan]

Hello Marcel,

to calculate affine transformation parameters you must have at least 3 
points in both coordinate systems.
LV95_y = Y0 + a * local_y + b * local_x

LV95_x = X0 + c * local_x + d * local_y

If you set up the equations for the three points, you get to linear 
equation systems, one for Y0, a, b unknowns, and another fo X0, c, d 
unknowns.

It is highly recommended to use more points and least squares estimation 
for the parameters.

Best regards,
Zoltan


On Tue, 7 Oct 2014, Marcel Stadelmann wrote:

> Hi,
>
> I would like to make an affine transformation with a vector layer shape file, using the Affine Plugin. I know from two points the correct coordinates:
> local_y	local_x	LV95_y	LV95_x
> 9.065056	7.70714	2753308.44	1166381.26
> 9.065056	-5.085236	2753295.68	1166391.31
>
> How can I calculate the transformation parameters?
>
> Marcel
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