improfile() through 3D image?

Hello,

I have a 3D image set (i.e., a stack of CT images), I would like to get a line profile through this 3D image set similar to what improfile() does on a normal 2D image. I can't find anything that does this. Help!

Thanks, Justin

Answer 1

[Walter Roberson]

If you can calculate the coordinates that you want to sample at, then you can use interp3(). But calculating the coordinates might require using something like http://en.wikipedia.org/wiki/Bresenham's_line_algorithm

[Justin Solomon]

Thanks for the advice. I was able to find an implementation of Bresenham's line algorithm.

I have a follow up question about interp3().

I've got a 3D image, I, and I've defined a coordinate system (x,y,z) for I. Note that because I'm dealing with images, x actually corresponds to the second dimension (columns) of I,. Further, I have a list of points [Xprof Yprof Zprof] that define a line through the image (i.e., Xprof, Yprof, and Zprof are all vectors of length n where n is the number of points in the line). Now I would like to use interp3() to get values of I along the line defined by [Xprof Yprof Zprof].

I'm worried that I'm mixing up the x and y axis when I call interp3(). Should I do

1. HUs = interp3(y,x,z,I,Yprof,Xprof,Zprof);

or

2. HUs = interp3(x,y,z,I,Xprof,Yprof,Zprof);

Below is the calling sequence for interp3() described in the help menu.

VI = interp3(X,Y,Z,V,XI,YI,ZI)

I don't know if X is associated with the rows or columns of V. Any insight would be helpful.

Thanks, Justin