[PROJ] Proj / cs2cs differences

[Roberto Toldo]

Hello!

I found some issues/differences from the "proj" bin and "cs2cs" bin
utilities. I'm using the last version, directly compiled from Github.
Probably it's something due to my inexperience with the library, so please
bear with me :)

Specifically, I was trying to convert coordinates from geodetic to
EPSG:5174 ( Korean 1985 / Modified Central Belt).

I used proj with the parameters extracted from "projinfo EPSG:5174":
proj +proj=tmerc +lat_0=38 +lon_0=127.002890277778 +k=1 +x_0=200000
+y_0=500000 +ellps=bessel +units=m +no_defs

and then cs2cs with direct conversion parameters:
cs2cs +init=epsg:4326 +to +init=epsg:5174

However, I obtain quite different results.

For example, If I use lat_0 and lon_0 as input (127.002890277778, 38), I
obtain exactly false_easting and false_northing (200000, 500000) when using
proj4 (as expected), while I obtain something different when using cs2cs
(200185.04 499695.19).
I would be expecting the same results. I tried with other coordinate
systems (e.g., EPSG:32633 UTM zone 33N), and I noticed no differences
between proj and cs2cs results.
Can anybody help me understand what the reason for the differences is? Are
the parameters used internally by cs2cs different for EPSG:5174? I also
tried setting the accuracy, but it doesn't seem to work.

Thanks,
Roberto
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