ex07_gap_methods
This example extends the internal-gap reconstruction from merge2d ex08 into
three dimensions. A spherical region with radius 18 grid units is removed from
a smooth reference volume. The complete reference and gapped model are shown
before reconstructions made with all six vertical methods available through
the merge3d -S option.
The reconstructions use:
gmt merge3d model.nc?gapped -R0/100/0/100 -I2 -T0/100/1 -Fvalue -Sa+g -Gakima.nc
gmt merge3d model.nc?gapped -R0/100/0/100 -I2 -T0/100/1 -Fvalue -Sc+g -Gcubic.nc
gmt merge3d model.nc?gapped -R0/100/0/100 -I2 -T0/100/1 -Fvalue -Se+g -Gstep.nc
gmt merge3d model.nc?gapped -R0/100/0/100 -I2 -T0/100/1 -Fvalue -Sl+g -Glinear.nc
gmt merge3d model.nc?gapped -R0/100/0/100 -I2 -T0/100/1 -Fvalue -Sn+g -Gnearest.nc
gmt merge3d model.nc?gapped -R0/100/0/100 -I2 -T0/100/1 -Fvalue -Ss0.25+g -Gsmoothing.nc
The +g modifier bridges internal missing layers independently in every
vertical column. It does not extrapolate beyond the model’s vertical domain.
Akima, cubic, and linear interpolation provide continuous reconstructions;
step and nearest-neighbor retain discrete behavior; and the smoothing spline
uses a fit parameter of 0.25.
This example intentionally omits -H: filling each native x-y layer first
would reconstruct the spherical hole before the six vertical -S methods
could be compared. Horizontal -H methods are demonstrated by the equivalent
merge2d gap-method example and use the same directives in merge3d.
The horizontal figure shows slices at z = 50, while the vertical figure
shows sections along y = 50. The dashed blue circle marks the original
spherical gap in both central cross-sections. The dashed black line in the
horizontal panels marks the vertical-section location.
Run:
./ex07_gap_methods.sh
The script verifies that the unfilled model remains missing at the sphere center, every method fills the internal gap, and every pair of methods produces a distinct vertical reconstruction. It creates:
ex07_gap_methods_horizontal.png
ex07_gap_methods_horizontal.pdf
ex07_gap_methods_vertical.png
ex07_gap_methods_vertical.pdf
Figures
