Grdview, (annotated) contours on a 3D perspective plot

Q&A
1

Hi, I would like to produce a plot which is a 3D perspective with contours, possibly annotated.

I want to get a 3D perspective plot like this

ex51-1
ex51-11519×1425 454 KB

This required 1) a call to grdimage -I to produce a color map w/shading and 2) a call to grdcontour -C -A... to produce contours incl annotations - on top of the color map.

Maximum what I’ve been able to get with grdview so far is the two variants below. One with shaded relief, smooth color palette making contours not possible and the other with contours but not smooth color palette:

ex51-2-1
ex51-2-11995×1192 532 KB
ex51-2-2
ex51-2-21995×1176 510 KB

The grdview scripts:

gmt begin ex51-2-1 png -C
gmt makecpt -Cturbo -T-72/-3 -H > "BB_bathymetry.cpt"
gmt grdview "$BB_Bathymetry" -I+a-135+nt0.75+m0 -p45/30/-80 -Qi50c \
     -C"BB_bathymetry.cpt" \ 
     -Jz0.05c -B20s -Bz10 -BNEZ -JM4i \
     -R-63:39:37/-63:38/44:40:20/44:41:40/-80/0 \
     -N-80+glightgray
gmt end

gmt begin ex51-2-2 png -C
gmt makecpt -Cturbo -T-70/-5/5 -H > "BB_bathymetry_contour.cpt"
gmt grdview "$BB_Bathymetry" -I+a-135+nt0.75+m0 -p45/30/-80 -Wc0.25p,black,solid \
  -C"BB_bathymetry_contour.cpt" -Qs -Jz0.05c -B20s -Bz10 -BNEZ \
  -JM4i -R-63:39:37/-63:38/44:40:20/44:41:40/-80/0 -N-80+glightgray
gmt end

I want a smooth color scale on 3D perspective plot with shades plus contours (annotated if possible) but couldn’t find out how to plot it the way I want. I can plot with a smooth color palette but then plotting contours only with a second call and a special categorical .cpt file for the contours seems not possible? If I use the .cpt that is good for contours, every 5 meters, smooth color plot seems not possible?

Suggestions are much appreciated.

2

I think what you want is not available. However, maybe you can get it close by creating a very dense CPT and only turn on contours for every 5 m even if the CPT is, say, every 2 cm. Just guessing.

3

Thanks! I suspected this.

BTW the related example 4 from the gallery https://docs.generic-mapping-tools.org/latest/gallery/ex04.html misses the second plot, namely, “figure ex04c”

GMT4 docs shows both plots as it should.
https://docs.generic-mapping-tools.org/4/gmt/html/GMT_Docs.html#x1-1390007.4

4

Thanks, we may need to do a subplot on this to avoid too much special scripting for one example.