Locating cylindrical objects from perspective projections

The authors address the problem of finding the 3D position and orientation of a circular cylinder using one view and known values of its radius and height. Elliptical projections of the circular ends and straight line projections of the cylinder sides can be used to calculate the cylinder position up to 5 degrees of freedom. It is shown that the viewpoint can be independently computed based on either the elliptical projection of the circular top or the straight line projection of the cylinder sides. There are two solutions (one in a degenerate case) using the elliptical projection. With the side projections, one can obtain unique solutions. If one has only the line positions but no terminal points due to occlusion or imperfect image segmentation, one can still compute a partial solution that has a degree of translational freedom along the cylinder axis. A vision recognition program is implemented for recognizing and locating a cylinder to test the solution methods, based on detection of elliptical features in the image which guides the search for side edges