Gridding, contouring, and masking of unconstrained areas

    ship_d = gmtread("@ship_15.xyz", table=true)
    region = gmtinfo(ship_d, inc=1)

    R = region[1].text[1][3:end]
    Gship  = nearneighbor(ship_d, region=R, inc="10m", S="40k")
    grdcontour(Gship, frame=(axes=:WSne, annot=2), cont=250, annot=1000,
               labels=(dist=5,), proj=:merc, figsize=7.5)

    ship_10m = blockmedian(ship_d, region=R, inc="10m")
    Gship = surface(ship_10m, region=R, inc="10m")
    mask!(ship_d, region=R, inc="10m", fill=:lightgray, tiles=true, x_off=9.1)
    grdcontour!(Gship, cont=250, annot=1000, labels=(dist=5,),
                range=(-8000,0), frame=:same)

    mask!(ship_10m, region=R, inc="10m", x_off=-9.1, y_off=9.5, frame=:same)
    grdcontour!(Gship, cont=250, annot=1000, labels=(dist=5,), range=(-8000,0))
    mask!(end_clip_path=true)   

    Gship_clipped = grdclip(Gship, above="-1/NaN")
    grdcontour!(Gship_clipped, cont=250, annot=1000, labels=(dist=5,),
                range=(-8000,0), x_off=9.1)
    coast!(land=:gray, shore=:thinnest, frame=:same)
    info = grdinfo(Gship, C="n", minmax_pos=true)
    plot!(info, marker=:star, ms=0.4, i="10,11", lw=:thick)
    text!(text_record([-0.3 3.6], "Gridding with missing data"), region=(0,3,0,4),
          font=(24,"Helvetica-Bold"), justify=:CB, no_clip=true, figscale="1i",
          proj=:linear, show=1)