visualization of 3D matrix: how do I swap the y and z axis?

The Matlab ordering for 3D matrices are: column (y) - row (x) - page (z).

I am using imagesc() to display slices of seismic data: imagesc( S(:,:,1) ); % first page

My first problem is this: how do I slice in another direction? imagesc( S(:,1,:) ); does not work :-(.

My next problem is that for seismic it is customary to have z axis downwards: column=z, row=x, page=y.

I have solved this by a "hack": when reading in the data from an ascii file I swap the y and z axes. The result is that imagesc( S(:,:,1) ); in reality is displaying the seismic for y=y1.

There must be some better way to do this?

Thanks in advance for any answers!

Answer 1

[Andrew Newell]

You can use permute to rearrange the order of the dimensions and axis to to place the origin in the upper left corner:

S = permute(S,[3 1 2]);
% Your plot commands
axis ij

[Andreas W.]

Thanks Andrew. That worked beautifully :-).

Answer 2

[Wayne King]

Hi Andreas, you are using imagesc() to display 3D data??

Are you sure you are not talking about surf() or something other display method? imagesc() does not work on a 3D matrix except for a truecolor image.

If you use surf(), you can reverse the Z-axis direction

k = 5;
n = 2^k-1;
[x,y,z] = sphere(n);
surf(x,y,z); set(gca,'ydir','reverse');

[Andreas W.]

Hi Wayne. Sorry for a poorly explained question. I have improved my question text.