There is non-uniform spacing in grid.y that is taken into consideration when using pcolor. This is causing the difference in how pcolor renders the image compared to imagesc. You need to determine if this is correct or not.
%load the grid
load('test_grid','-mat'); %load the grid struct
plot(diff(grid.y))
Note that pcolor uses the supplied values of X and Y to display the image while imagesc only used the first and last value and assumes equal spacing between the points.
- If x has more than two elements, imagesc uses the first and last elements and ignores the other elements.(ref)
The code below shows this. In particular, note the straight vertical line at the top of the center plot.
figure
tiledlayout(1,3)
nexttile
Z = grid.z';
C = pcolor(Z,'EdgeColor','none');
nexttile
C = pcolor(grid.x,grid.y,Z,'EdgeColor','none');
nexttile
imagesc('XData',grid.x,'YData',grid.y,'CData',Z)
axis tight
In short, images cannot have unequal spacing between pixels. So either you cannot use an image to display your data, or you need to update your data to use equal spacing.
Here, if you ignore the grid x and y values, you can get the images to align.
figure
C = pcolor(Z,'EdgeColor','none');
h_im=imagesc('CData',C.CData);
h_im.AlphaData = 0.5;
axis equal tight
figure
imshowpair(Z,C.CData)
axis xy equal
