#
# The Delaunay triangulation filter is an adjunct to the support for
# concave hulls.  It can be used on its own either for original use
# in 2D plots or as a way to generate a triangular tesselation for
# a 3D surface defined by a scattered set of points as shown here.
#

if (!strstrt(GPVAL_COMPILE_OPTIONS, "+CHI_SHAPES")) {
    print "Your copy of gnuplot was not built with support for chi shapes"
} else {
    set style fill solid border lc "black"
    unset colorbox
    set palette viridis
    set xyplane 0
    set isotropic
    set view 60,127, 1.55
    set border 15
    set tics format ""
    unset ztics
    set grid x y

    set multiplot layout 1,2

    set pm3d lighting primary 0.5 spec 0.2 spec2 0.3
    splot 'hemisphr.dat' using 1:2:3 delaunay with polygons fc palette z title "pm3d lighting"

    set pm3d nolighting
    splot 'hemisphr.dat' using 1:2:3 delaunay with polygons fc palette z title "no lighting model"

    unset multiplot
}


Click here for minimal script to generate this plot