Calculating depth at certain points of a trisurf plot

I have made a plot of a reservoir layer in the subsurface using griddata and surf. Now I want to know how much the plot differs when I use the Delaunay equation instead of griddata. With griddata I have te values of the depth at the points of:

if true
x=35:1:48;   
y=74:1:85;
[X,Y]=meshgrid(x,y);     
end

I would like to know (I think by interpolation) what the depth of the surface is at every point of the meshgrid.

if true
clear
close all
clc
x=35:1:48;   
y=74:1:85;
[X,Y]=meshgrid(x,y);          
xzylRange = 'A1:N12';
filename = 'depthtopmainreservoir.xlsx';
sheet = 1;
xlRange = 'B19:B97';
ylRange = 'C19:C97';
zlRange = 'D19:D97';
XX = xlsread(filename,sheet,xlRange);
YY = xlsread(filename,sheet,ylRange);
Z = xlsread(filename,sheet,zlRange);
ZZ=Z./1000;              %setting depth from [m] to [km] for scale
z=griddata(XX,YY,ZZ,X,Y,'cubic');
figure(1)
scatter3(XX,YY,ZZ,'fill')
figure(2)
surf(X,Y,z)
hold on
scatter3(XX,YY,ZZ,'fill')
xlabel('x in [km]')
ylabel('y in [km]')
zlabel('Depth in [km]')
colorbar
daspect([1 1 0.1]);
hold off
figure(3)
[c,h]=contour(X,Y,z);
xlabel('x in [km]')
ylabel('y in [km]')
title('Depth in [km]')
clabel(c,h)
colorbar
figure(4)
[c,h]=contour3(X,Y,z);
hold on
scatter3(XX,YY,ZZ,'fill')
daspect([1 1 0.1]);
xlabel('x in [km]')
ylabel('y in [km]')
title('Depth in [km]')
clabel(c,h)
colorbar
hold off
%%delaunay equation
figure(5)
plot(XX,YY,'.','markersize',12)
xlabel('Longitude'), ylabel('Latitude')
grid on
figure(6)
tri = delaunay(XX,YY);
hold on, triplot(tri,XX,YY), hold off
figure(7)
hidden on
trimesh(tri,XX,YY,ZZ)
xlabel('x'),ylabel('y'),zlabel('Depth in [km]');
hold on
scatter3(XX,YY,ZZ)
colorbar
hold off
daspect([1 1 0.1]);
figure(8)
triZ = delaunay(XX,YY);
hold on, trisurf(triZ,XX,YY,ZZ);, hold off
daspect([1 1 0.1]);
end