Seasons time-lapse - alignment

In the previous post, I described the Seasons project: a time-lapse of hundreds of pictures taken from nearly the same viewpoint over the years. The hardest challenge wasn’t taking the pictures or assembling them, but aligning them. You might have noticed the nearly part about viewpoint in the above paragraph. Indeed, it’s an approximation. I’m a human being, not a tripod. The position changes ever so slightly, and so does the exact angle.