[gembud] GDVINT Error: Can't make zagl grid

[corepuncher <corepuncher@xxxxxxxxx>]

I was running GDVINT a few weeks ago on my home computer, and was making
both zagl and thta grids.

Now, about 2 weeks later, it suddenly will not work, and spits out:

[GDVINT  +4]    Warning--no surface elevation grid exists.

To my knowledge, nothing has changed on this machine.

Is there a way maybe to find this surface elevation grid file and add it
(not sure where it goes either, thanks.