grdimage gives no result with external .cpt file unless using illumination

Added by Lynne 4 months ago

I need to use grdimage with an external color palette file (created by makecpt), without illumination, but it looks like there's a bug. It used to work several years ago, but no longer. Problem in both gmt4 and gmt5 versions that I downloaded in early 2014. If I have grdimage create its own color cpt file within the command, it is OK. It is also OK with external gray shade cpt, and it is OK if I use a color cpt palette and also grdgradient.

This works, makes a nice image, without illumination (and works with any of your built-in palettes), but I need to use my own palette from makecpt:
gmt grdimage pacprop.grd -Crainbow $J1 -R -K -O >

This produces a good-looking cpt file:
gmt grd2cpt pacprop.grd -Crainbow > test.cpt
But then using it (or a palette I make using makecpt) produces blank image (as does any input cpt I create, unless it's grayscale or unless I illuminate, which I don't want to do):
gmt grdimage pacprop.grd -Ctest.cpt $J1 -R -K -O >

Using illumination works, makes an image, but I don't want illumination:
gmt grdgradient pacprop.grd -Gtest_i.grd -Nt1 -A45
gmt grdimage pacprop.grd -Ctest.cpt -Itest_i.grd $J1 -R -K -O >

How do I make a color image, with external color palette generated in makecpt, and no illumination?
Thanks, Lynne

Replies (1)

RE: grdimage gives no result with external .cpt file unless using illumination - Added by Paul 4 months ago

My first reaction is that this bug (if it is/was a bug) was fixed a long time ago since we have no problem making tons of grdimage plots using external or internal CPTs with or without illumination. It is soon 2018; running a GMT version from 2014 is not advisable. Why dont you upgrade and report back - alternatively post a short example that demonstrates your case (I cannot run your commands since no data files, etc).