Just an fyi, the npp/lpp/osp refer to the "no parallax point/ least parallax point/ optimum stitching point. Some people call it different things, but basically you need to rotate your lens and camera around the point within the lens where the light rays converge. Without rotating around that point it is very diffucult to get a good stitch in smaller spaces due to parallax.
ps. the GR was referring to "grey robust: