Just in case you have R within reach, have a look at the post "Similarity and affine transformations in R" [1], which explains how to use my R plugin "vec2dtransf" to perform affine transformations.
Regards, Germán ---- [1] http://geotux.tuxfamily.org/index.php/en/geo-blogs/item/302-affine-and-similarity-transformations-in-r [2] http://cran.r-project.org/web/packages/vec2dtransf/index.html 2014-10-07 13:59 GMT-05:00 Siki Zoltan <[email protected]>: > 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 >> _______________________________________________ >> Qgis-user mailing list >> [email protected] >> http://lists.osgeo.org/mailman/listinfo/qgis-user >> >> _______________________________________________ > Qgis-user mailing list > [email protected] > http://lists.osgeo.org/mailman/listinfo/qgis-user > -- ----------- |\__ (:>__)( |/ Soluciones Geoinformáticas Libres http://geotux.tuxfamily.org/ http://twitter.com/GeoTux2
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