This photo is not from me
Its just for show why you use this point of view, unless a top view
Actually, that was me and it was sort of a rush job. A real dick is much easier to do that stuff with, as the whole head area is skin and looks about the same. The can wasn't a good choice as it has well defined transition points. Same stuff applies to the "Z-axis" measurements where a tape drapes down over the head. Also, none of these things add any fixed amount which can be easily subtracted or whatever. They vary widely depending on how they're done,distances,angles,etc.
You also might notice that it gets difficult to line up a measuring instrument's numbers with what's being measured below it when you get too close to it. Even in the "straight down" view on the left it's hard to tell and gets substantially worse with the non-linear curved effect some lenses give. The obvious remedy is to look down from an adequate distance (around where your own eyes would be). It not only minimizes this outward angle thing with the far ends of the ruler, but also gives a much better idea of what position your body is in.
Take Care
PS- As All4Kim pointed out, nothing moves in that shaving cream picture. The ruler just stayed taped to the can the whole time. Sorry if it looks otherwise.
