Gmt velo does not scale the arrow heads automatically? (GMT 6.3)

Q&A
1

Hi everyone,

I have migrated from GMT 6.0 to GMT 6.3 and I have noticed that gmt velo operates in a slightly different way now. For example, for this line of code:

cat $FILE | gmt velo -W0.02i -Gblue -Se0.10i/0.95/8

In GMT 6.0, the size of the arrow head automatically adapts to the length of the arrow. That means that for small arrows the arrow head scales automatically and becomes smaller so that it does not cover the arrow tail itself.

However, my experience with GMT 6.3 is that the arrow head size (both the default value or a value selected manually) is the same for all arrows contained in our input file. Since for some plots it is interesting to have varying arrow head sizes, is there a way of doing that in GMT version 6.3? Many thanks!

2

I cannot easily check what 6.0 did but in general (as well as in plot), you have a fixed size head but you can make it vary depending on vector length via the +n modifier to -A the same way it works in plot.

1 Like
3

Thank you Paul! I have now used the +n modifier to implement varying arrow head sizes and it works. For some reason in version 6.0 I was getting this head size variation by default.