Description of the desired feature
Modules like meca, velo, etc. plot advanced symbols in seismology and geodesy and use a geographic region (-R), map projection (-J) and input longitude, latitude to place these features on a map. There are times when we also would like to plot such a symbol outside a map, such as in a legend. In legends, there usually is no geographic region nor projection, and at best there is a Cartesian -R -J set up for placing information. Because the above-mentioned tools reads longitude, latitude of where a feature is it becomes a guessing game to pick -R -J and input coordinates to align the symbol, say, centered in a legend.
One way to handle this would be to add a new option to these modules that, like -D for colorbars or scales, deals with this issue. Examining the various modules I see that the option -I (for information) is available [or -Z if coupe is can be excluded]. Thus, a solution may be this:
- Add -I[g|j|J|n|x]refpoint for specifying where the special symbol should be plotted (with the usual ways of refpoint values like coordinates or codes)
- When -I is used the input longitude, latitude is ignored and placement is given via -I instead.
For instance, to center a focal mechanism in the middle of a 5x10 cm legend area we could do
gmt meca -R0/10/0/5 -Jx1c -Sm2.5c -M -G110/168/255 -T0 -W0.5p -Yh+0.5c -IjCM <<- EOF
-159.70 54.81 39 0.82 -0.68 -0.14 0.63 0.34 -0.40 25
EOF
and the actual earthquake location (-159.70 54.81 ) is simply ignored. I think the proposed mechanism will make it easier to add special symbols such as GPS velocity with error symbols and focal mechanism to user legends.
Comments, @joa-quim and @seisman? Apart from meca and velo, does it make sense to extend this solution to polar, coupe, and sac?
Description of the desired feature
Modules like meca, velo, etc. plot advanced symbols in seismology and geodesy and use a geographic region (-R), map projection (-J) and input longitude, latitude to place these features on a map. There are times when we also would like to plot such a symbol outside a map, such as in a legend. In legends, there usually is no geographic region nor projection, and at best there is a Cartesian -R -J set up for placing information. Because the above-mentioned tools reads longitude, latitude of where a feature is it becomes a guessing game to pick -R -J and input coordinates to align the symbol, say, centered in a legend.
One way to handle this would be to add a new option to these modules that, like -D for colorbars or scales, deals with this issue. Examining the various modules I see that the option -I (for information) is available [or -Z if coupe is can be excluded]. Thus, a solution may be this:
For instance, to center a focal mechanism in the middle of a 5x10 cm legend area we could do
and the actual earthquake location (
-159.70 54.81) is simply ignored. I think the proposed mechanism will make it easier to add special symbols such as GPS velocity with error symbols and focal mechanism to user legends.Comments, @joa-quim and @seisman? Apart from meca and velo, does it make sense to extend this solution to polar, coupe, and sac?