This works for me. See that cct needs 3 coordinates. x,y,z $ echo 59770.038 101069.654 0 | cct +proj=helmert +x=334491.216 +y=6950332.853 +theta=-49800 368362.0519 7062761.9368 0.0000 inf
On Wed, 21 May 2025 at 00:36, Daniel Farfán via PROJ <proj@lists.osgeo.org> wrote: > I've been trying to solve this problem but was unable to, so I kindly > ask for help. > > I have 3 coordinate points in a local grid: > A': 59770.038, 101069.654 > B': 59214.93435, 98996.58573 > C': 58444.7795, 99231.37298 > > Corresponding coordinate points in EPSG:32719 CRS: > A: 368362.117, 7062761.917 > B: 368318.78, 7060616.253 > C: 367514.826, 7060660.088 > > So, I've determined that to convert from the local points to the > EPSG:32719 CRS, I have to displace the x axis by 334491.216, the y > axis by 6950332.853, and rotate counterclockwise by 13.8333 degrees. > > I have managed to get the following to work: > > cct +proj=helmert +x=334491.216 +y=6950332.853 +theta=-49800 > When I input the coordinates in the local grid, i get the > corresponding coordinates in EPSG:32719 > > What I'm struggling with is to use the conversion with cs2cs: i think > I need to define the transformation as a custom CRS, to be able to do > something like: > cs2cs "+proj=helmert +x=334491.216 +y=6950332.853 +theta=-49800" +to > EPSG:32719 > > but that's not working. > > My final goal is to use the custom CRS proj string (or WKT equivalent) > in GDAL and QGIS to be able to transform on the fly the local grid > data to EPSG:32719. > > Any help would be appreciated. Thanks in advance. > > -- > Daniel Farfán > > _______________________________________________ > PROJ mailing list > PROJ@lists.osgeo.org > https://lists.osgeo.org/mailman/listinfo/proj >
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