[PROJ] Transformation for local grid

Pierre Chaponniere pierrechapo at gmail.com
Mon Feb 10 01:11:03 PST 2020


Dear all,

I am struggling to elaborate a pipeline with proj v6.3 that would transform
lat long coordinates to a local grid system.
>From what I see, I have all the required parameters, so I did a 3 step
pipeline :

1/ transform from lat long wgs84 to projected using tmerc.

2/ run horizontal transformation which is a rotation around an origin - I
was thinking of using the the Molobadekas transform for this purpose

3/ vertical shift for which I have an origin as well, east and north slope
entries in ppm - i still need to figure how I'll pass this one...

So my proj line so far looks like this :

proj +proj=pipeline +step +proj=tmerc +lat_0=-1.90 +lon_0=115.90
+y_0=538.374 +x_0=5200.27 +ellps=GRS80 +step +proj=molobadekas
+convention=coordinate_frame +x=-9.85881089465147 +y=-0.172038726321603
+s=17.60710142 +rz=1485.3205006576768028 +px=5225.30897756133
+py=-830.070127940344

But I keep on having errors as 'malformed pipeline' or 'non-angular input
coordinates'...
Even trying to pass the Molobadekas transform on its own, I struggle...

Do you see anything that I am doing totally wrong here ?
Would be really appreciated to have your insight on this !

Thanks heaps,

Best regards,

Pierre C
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