Right straight homogeneous generalized cylinders with symmetrical cross-sections: recovery of pose and shape from image contours

The straight homogeneous generalized cylinder (SHGC) comprises a class of objects for which recovery of pose and shape from image is generally an underconstrained problem. It is shown that for a major subclass of SHGCs, namely, the right straight homogeneous generalized cylinders, the 3-D pose (tilt and slant) and shape (cross section and scaling function) can be completely determined if the cross sections are symmetrical. From the mutual orthogonality of the cylinder axis, the symmetry axis and transverse axis of the cross section, their slants can be determined from their tilts, the 2-D orientations of their projections onto the image. The 2-D cylinder axis and skewed symmetry axis of the cross sections are extracted by using the property that tangents to the image curves at corresponding points meet on the axes. Once the pose is recovered, the cross section and scaling function of the object can also be determined from the cross section contour and extremal contours, respectively