Grid transparency

Hi,

I am using grdimage to plot two grid files (topography and slab grid file). The map (attached) shows ocean floor of the subducting plate in black color, which is perhaps due to the shallow depth values associated with those grid points. I used grdclip to change the "Z-vlaues" of each grid point shallower than 10km to NAN. I thought that NANs will be mapped transparent and bathymetry of the ocean floor will be visible but now the black portion turns into white and the ocean floor of the underlying layer is still not visible. I used the following commands:


system "grdimage -Y1.4i $grdfile $jflag $rflag $bflag -C$cptfn -Ishadow -V -K > $psfn\n"; (to plot the topography grid file)
system "grdclip slabsurf1.grd -Gslabsurf_cliped.grd -Sb10/NaN -V\n"; (processed slab grid file)
system "grdgradient slabsurf_cliped.grd -A45 -Gshadow1 -Nt -V\n";
system "grdimage slabsurf_cliped.grd $jflag $rflag $bflag -C$depcpt -O -V -K >> $psfn\n"; (to plot the slab grid file)


I would be extremely grateful to have any suggestions in this regard.


Thanks

Abhash kumar

University of North Carolina at Chapel Hill


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