Now, there's no perfect solution for mosaicking these together. One way or another, the arm has to be truncated somewhere. Whoever assembles the mosaic has to figure out a way to discreetly cut and paste to hide the truncation as neatly as possible. I've shown a zoomed-in view of the shoulder joint from Ed Truthan's mosaic, where you can see that the arm has been amputated. There's a tiny area where a view of the underside of the arm fades into a view of the topside of the arm, but it's hard to spot unless you're looking for it.

It's no accident that the arm is almost completely out of view -- they wanted to get the best-looking portrait with the fewest seams possible, and the way that they shot it allowed them to have no visible seams except for that one little spot at the shoulder. The video below shows the complex arm motions necessary to capture these 64 images. When I imagined the rover shooting this sequence, I imagined the arm holding still and the turret pivoting up and down and side to side like an az-el mount on a telescope. But that's not how they did it at all. The arm moves significantly for each and every frame. Why do they do that?

Take a close look at the turret to see if you can identify which part is the MAHLI. If you watch it very closely, you will see that for all the arm's gyrations, MAHLI itself hardly moves in space. They performed the motions in such a way that the origin of the point of view of every single image was at the same spot in 3D space. That means that there is virtually no parallax from image to image, no places where a shift in perspective made a foreground bit of rover shift with respect to a background bit of rover. Without all those gyrations to keep MAHLI still, there would have been seams galore in the resulting image. Very, very tricky of them!