Hello,
I have a question about the Image2ProbeTransform that is used in .mha files. As far as I can tell, all of the matrices have to be 4X4 matrices. Please correct me if I’m wrong.
I have an ultrasound probe with an attached markers, and its position in a reference system (Probe2ReferenceTransform) is known.
The thing is, the image plane itself is 2D, and while (Plus applications user manual: Definition of commonly used coordinate systems) says that the Z-axis is a cross product of the X-axis and Y-axis, I have been having some confusion about how I should define the transformation matrix.
Say that the image coordinates are in (u, v) and I want to transform it to (x,y,z) in the probe coordinates. The two are linked via
[x [a1 a2 [p1
y = b1 b2 * [u + p2
z] c1 c2] v] p3]
or [x; y; z] = [a1, a2; b1, b2; c1, c2] * [u, v] + [p1, p2, p3]. Semicolons denote new rows and commas denote new columns within a row a la MATLAB.
Values are
a1 = 0.3467;
a2 = -0.1316;
b1 = -0.2807;
b2 = -0.0620;
c1 = 0.1460;
c2 = -0.0394;
p1 = -109.1116;
p2 = 154.9904;
p3 = 5.9658;
I am thinking of a 4X4 Image2ProbeTransform
[a1, a2, 1, p1;
b1, b2, 1, p2;
c1, c2, 1, p3;
0, 0, 0 1]
but it seems that while Slicer can track an image via this method when I put it all into a .mha file, the image gets zoomed in, pixelated, and cut up from a 2D image into an odd slice like this:
I would greatly appreciate any help!