Load global relief using grdimage on general perspective projection

Q&A
1

Hi,

I want to plot a circular relief map and show the elevation of one hemisphere. I found that when I use grdimage for global relief, the map won’t load if I use a global range i.e. -Rg option of grdimage

I have tried

gmt grdimage @earth_relief_15s -JH5c -Rg
gmt grdimage @earth_relief_15s -JG0/0/5c -Rg

But both didn’t work. Is there anyway I can still use -JG to map a hemisphere’s elevation? I do like its shape.

Great thanks.

2

Hello @XiaoChenhan
If you download the earth_relief remote dataset for a global range with a resolution of 15s (15 arc-seconds), this is 2.6 GB (please see the table at GEBCO Earth Reliefs — Remote Datasets documentation). This may cause problems. I think a lower resolution should be sufficient for a global map in most cases. Can you please try using a lower resoultion and check if this works?

3

Hi @XiaoChenhan

You can also NOT specified the resolution, and GMT will download the optimal resolution needed for your map based on it region and projection.

gmt grdimage @earth_relief -JH5c -Rg

4

I have downloaded the dataset of 15s for a global range already, but yeah it seems only when I don’t specific the resolution the map could load. The gmt reduced the resolution using gausian filter. Thank you very much for your advice.

5

Thanks a lot, this worked well. I mean I wanted a high resolution but I guess you can’t have both large range and high resolutions.