Thread Subject:

ellipse defined by a plane intersecting a cylinder

Hi all,

A little background: I have a cross sectional image of a fibre reinforced plastic. Some of the fibres are perpendicular to the image (and can be seen as circles), others are at an angle (and can be seen as ellipses).

I am looking to find the angle that these fibres (that are shown as ellipses in the particular cross section) are to the image.

My best guess is to determine the equation of the ellipse defined by a plane and a cylinder. I can compare the circularity of the intersected plane / cylinder to the circularity of the fibre (from an image analysis software).

Bottom line is - is anyone aware of an existing function to determine the parametric equation of an ellipse generated by the intersection of an arbitrary plane and a cylinder?

Any help would be greatly appreciated.

The math is actually very simple. The ratio of the major to the minor diameter is equal to the projection into the X direction versus the Y direction. Just fit the ellipses, determine the major and minor diameters, and divide the two.