It's been awhile since I've checked in on the technology but, you are right, the "dots" seem like those used for "attaching" a CGI face or elements of one. This is either a very simplified or superficial version of what I'm familiar with or the technology has vastly improved. It is possible that a younger Harrison composite made up from appearances in earlier films, or simply created from whole cloth by CGI artists, is a fairly easy overlay onto the man himself. The musculature is the same, the impulses firing the expressions are the same, so maybe it takes fewer location points than I thought. On the other hand this may be simply what they do for a long shot. If you notice the jacket locators are only on one side. Personally, I'd say that posture is just as great an issue when de-aging someone. If I were working on this film I'd be sure to have a massage therapist on staff! It's possible that HF was one of the actors who had himself "scanned" 20 years or so ago. I'm guessing that technology has improved greatly since then but even the older version might form an excellent "base layer" for a CGI artist to work with. These days it seems like a wise investment for an actor to get scanned as they reach different ages and to do the same if they beef up or lose weight to a great extent. Having those scans (owning them) might also be a useful precedent should anyone try to use your image in the future. It's a weird world but that doesn't mean we don't have to be prepared for it.