MATLAB: Whiteout regions on Contour Plot

contour

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My recommendation would be to set the interpolated data to nan in those regions before doing the contour plot.

However, since you have scattered data, you have the challenge of determining which points are "near enough" to explicit scattered data that they should validly be interpolated, and which points are instead to be interpreted as being too far from the scattered data and so should be interpreted as being outside the map.

You could consider a pdist2() approach but it appears you have a fair bit of data, so that would not be computationally feasible. You might be able to take advantage of kd-tree approaches; https://www.mathworks.com/help/stats/classification-using-nearest-neighbors.html

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MATLAB: How to plot interpolated grid data and original datapoint set in the same plot

You can always simply plot all your points:

plot3(Xi,Yi,Zi,'r.')

Or with scatter:

scatter(Xi,Yi,32,Zi,'filled')

But to me this seems to be more interesting:

pcolor(xi,yi,zi),
% shading flat % or interp adjust shading to fit taste
hold on
plot(xi,yi,'k.','markersize',6)
scatter(contour_grid.X,contour_grid.Y,23,contour_grid.Z,'filled')

Or you could compare contour-plots:

Levels = linspace(min(Zi(:)),max(Zi),10);
contour(Xi,Yi,Zi,Levels,'k')
hold on
tri=delaunay(contour_grid.X,contour_grid.Y);
[c,h]=tricontour(tri,contour_grid.X,contour_grid.Y,contour_grid.Z,Levels);
plot(contour_grid.X,contour_grid.Y,'k.')

You can find the tricontour function on the file exchange: TRICONTOUR

HTH

MATLAB: How to fill outside of contourf plot based on x,y,z data

You might want to try John D'Errico's File Exchange contribution inpaint_nans

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MATLAB: How to plot interpolated grid data and original datapoint set in the same plot

MATLAB: How to fill outside of contourf plot based on x,y,z data

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