Thanks again. “The customer” does not consider this solution.
But is there a way that I can make grdimage use text table in the form
lon(float),lat(float),bathy(float)?
I have tried the following commands:
$ grdimage gridfile.xyz -fi0x,1y …
$ grdimage gridfile.xyz -fig …
$ grdimage gridfile.xyz -fi0x,1y,2f …
but I get error message
grdimage: Not a supported grid format [gridfile.xyz]
Thank you.