I am a palaeoanthropologist and am working on bone curvature in 3D. I a trying to estimate a variable "torsion angle" from 3D coordinates. It has the potential to be very important in figuring out bone curvature.
I browsed your website and I took an online tutorial course in vector algebra but that didn't go into the right amount of detail and although I mentally see what needs to happen, I don't seem to be able to work it out.
In order to estimate one the variable on the femur, "torsion angle", I collected 4 points (a,b,c,d). c and d are at the bottom of the bone and a and b at the top. The torsion angle is basically the angle that is described between the two lines connecting "a and b" and "c and d".
/a
/
/
/b
c- - - - - - - - - - d
As these are distances from each other by depth I thought it would be necessary to create a 2D plane - project vector ab and vector cd on it and calculate the angle between them as if they are in 2D.
I have 4 points that have a horizontal relationship and could serve as the basis of the plane onto which the vectors are projected.
I was thinking of using a 4x4 matrix transformation but the literture I have found on this is somewhat confusing especially as I am not a mathematician or computer scientist. I am able to get my distances from the 3D data using excel and that is usually all we palaeoanthropologists need so please use simple terms ;-)
I browsed your website and I took an online tutorial course in vector algebra but that didn't go into the right amount of detail and although I mentally see what needs to happen, I don't seem to be able to work it out.
In order to estimate one the variable on the femur, "torsion angle", I collected 4 points (a,b,c,d). c and d are at the bottom of the bone and a and b at the top. The torsion angle is basically the angle that is described between the two lines connecting "a and b" and "c and d".
/a
/
/
/b
c- - - - - - - - - - d
As these are distances from each other by depth I thought it would be necessary to create a 2D plane - project vector ab and vector cd on it and calculate the angle between them as if they are in 2D.
I have 4 points that have a horizontal relationship and could serve as the basis of the plane onto which the vectors are projected.
I was thinking of using a 4x4 matrix transformation but the literture I have found on this is somewhat confusing especially as I am not a mathematician or computer scientist. I am able to get my distances from the 3D data using excel and that is usually all we palaeoanthropologists need so please use simple terms ;-)
