Mapproject (gmt6): EPSG 2180 conversion issue

Q&A
1

All,
I have difficulty projecting data into EPSG 2180 (https://epsg.io/2180), which I understand to be a transverse mercator, CM 19°, and false easting/northing of 500000/-5300000. Hence, I thought the following syntax should work (using ELLIPSOID GRS-80).

echo “16.9166666667 54.866666667” |
gmt mapproject -F -Jt19/0/1:0.9993 -R15/17/54/55 -C500000/-5300000
which results in:
366247.09 784376.38

However, using proj gives me a different result:
echo “16.9166666667 54.866666667” |
proj +proj=tmerc +lat_0=0 +lon_0=19 +k=0.9993 +x_0=500000 +y_0=-5300000 +ellps=GRS80 +towgs84=0,0,0,0,0,0,0 +units=m +no_defs +type=crs
366340.72 780117.32

The latter is the correct one, it seems.
What am I doing wrong with mapproject?

Thanks in advance,
Maarten

2

Think you mean

echo 16.9166666667 54.866666667 | gmt mapproject -F -Jt19/0/1:1 -R15/17/54/55 -C500000/-5300000 --PROJ_SCALE_FACTOR=0.9993

366340.720034 780117.320116

3

or

echo 16.9166666667 54.866666667 | gmt mapproject -J2180
366340.720033   780117.319413
1 Like
4

I see, I particularly like the last one, where we can use the EPSG code. I was not aware of that.
Many thanks for the swift response!
Maarten