Plot symbols to annotate the centers of closed innermost contours

[anbj]

grdcontour -T allows to annotate the centers of closed innermost contours with a label. What about adding the plot -S machinery also, so that one may use symbols instead of labels? E.g., triangle indicating upward closing, and inverted triangle indicating downward closing.

This is partly related to my #559, in my quest to differentiate upward/download closing contours and how to extract contours based on this (with e.g. grdcontour -D).

[PaulWessel]

Since it involves two separate symbols always (right?), do we really use the full plot -S for this? That is a very extensive syntax. Maybe up/down triangles makes sense, but having squares and circles would then require captions etc so what is the point?

[anbj]

Yes, you’re right. Up/down triangle (and other ‘binary symbols’ that make sense) would be nice.

[anbj]

(Isn’t a triangle often used to indicate summits/peaks on maps..?)

[anbj]

Closing this.

While I like the idea of having a symbol in the innermost closed contour, it should represent an actual point of minimum/maximum value (i.e. a peak/pit); not just the centroid of the contour.