imregionalmax to find peaks in 3d. I get an error Index exceeds matrix dimensions.

As said in the title I have got an error using imregionalmax. I have two monotone variable xVec, yVec and a third dependent variable imageMag that is experimental value. imageMag is 31x593. I have used

x=xVec;
y=yVec;
z=imageMag;
mesh(x,y,z,'FaceColor','interp')
ix = find(imregionalmax(z));
hold on
plot3(x(ix),y(ix),z(ix),'r*','MarkerSize',24)

but it says that index exceeds matrix dimensions. Why?

[Azzi Abdelmalek]

What line?

Answer 1

[Mike Garrity]

I'm just guessing, but that code snippet is assuming that x & y are full, 2D arrays. The mesh function allows for another case where they're vectors. From the name of your variables, I would guess that you've got that case.

If that's the case, you can expand the vectors out to 2D arrays using meshgrid :

[x,y] = meshgrid(xVec,yVec);
z = imageMag;
mesh(x,y,z,'FaceColor','interp')
ix = find(imregionalmax(z));
hold on
plot3(x(ix),y(ix),z(ix),'r*','MarkerSize',24)

[OldCar]

x and y are 1D vector (I think), they are 1x171 int32 and 1x51 int 32. I enclose xVec,yVec and imageMag. Thanks for your help. What do you think about?

[Image Analyst]

imregionalmax is meant to work with a volumetric image in 3D, not 1-D vectors.