Geographic Basemap - Axes Annotation Orientation

Q&A
1

I am creating a map using the Oblique Mercator projection. The labelling of the axes looks like this:

Long180
Long180191×309 5.98 KB

I want to rotate the Longitude annotations by 180°, so that they are more readable. Is that possible? I’ve looked at -B+a, but that doesn’t work for geographic basemaps. I’ve also looked at MAP_ANNOT_ORTHO, but that has no effect either.

2

Can you send the psbasemap command that makes the frame please? See MAP_ANNOT_OBLIQUE for various options.

3

Basemap command is:

psbasemap -Ba10g5 -JOA133.1/-2.7/143.95/500 -Rn-2600/2600/-800/800 -O -K >> %ps%

4

Thanks, looks like GMT4 syntax to me. Anyway, something like this

gmt psbasemap -Ba10g5 -JOA133.1/-2.7/143.95/9i -R-2600/2600/-800/800+un --FORMAT_GEO_MAP=dddF --MAP_ANNOT_OBLIQUE=0 > t.ps

avoids the overprinting. There should never be a need to rotate by 180 unless you are also rotating the figure after it is made. All the annotations above are readable and not backward.

5

Thanks for that Paul. You have actually revealed the underlying problem and that is I am rotating the figure 90° after it is made. The oblique equator is parallel to the x- axis and I want it to be parallel to the y-axis, hence the 90° rotation. I’ve asked the question about that in a separate post.
Thanks for the prompt reply.