output to GMT

[esyracuse]

Most of the figure-making I do is with Generic Mapping Tools, or GMT, which is really frequently used among seismologists. While I think I could manually convert a color palette in an Excel file to the proper format for GMT, I suspect it might be straightforward for the GMT format to be incorporated into your download options. Here is an example of the text from a GMT color palette file for a rainbow-style color map where the Z-data varies from -1 to 1.

cpt file created by: makecpt -Cseis

#COLOR_MODEL = RGB

-1 212 0 0 -0.777 212 0 0
-0.777 255 42 0 -0.555 255 42 0
-0.555 255 128 0 -0.333 255 128 0
-0.333 255 212 0 -0.111 255 212 0
-0.111 255 255 0 0.111 255 255 0
0.111 173 255 15 0.333 173 255 15
0.333 45 248 70 0.555 45 248 70
0.555 0 160 182 0.777 0 160 182
0.777 0 40 230 1 0 40 230
B 0 0 0
F 255 255 255
N 128 128 128

For the lines with 8 columns, here are the columns:

1. low boundary of the band
2. R-value for the low end of the band
3. G-value for the low end of the band
4. B-value for the low end of the band
5. high boundary of the band
6. R-value for the high end of the band
7. G-value for the high end of the band
8. B-value for the high end of the band
   Line beginning with “B” - RGB value plotted for data below the low end of the range given (here, Z<-1)
   Line beginning with “F” - RGB value plotted for data above the high end of the range give (here, Z>1)
   Line beginning with “N” - RGB value plotted for data for NaN values

As you can see, the values in columns 2/3/4 and 6/7/8 are the same, so each band is plotted as a single color, but if they differed, the R/G/B values would smoothly interpolate between the low and high ends of the bands. Also, although the bands are the same widths here, they need not be, as long as they are continuous (i.e., the low end of one band is the same as the high end of the previous band).

You can also find additional info at http://gmt.soest.hawaii.edu/doc/latest/makecpt.html and find examples of the default color palette options by Google Image searching “GMT color palette” (for example, http://geophysics.eas.gatech.edu/classes/Intro_GMT/gmt_www/gmt/doc/html/GMT_Docs/node187.html - here, the upper color palette below the “seis” is a plot of the color palette I gave above).

Thanks!

[figs512]

Ethan,
I was at AGU last week and many folks were asking about GMT... as well as ACRgis. Would it be possible to put up conversions for these programs?