Yes, a vectorized image generally counts as a derivative of the original, which means that distributing it without the original copyright holder's permission would be a copyright violation.
Of course, if you just want to make a nice poster to hand on your own wall, then you're probably safe — doing so might or might not be legal, depending on your local laws, but realistically, who's going to bother to sue you?
(Please note that I'm not trying to encourage you to break any laws, just stating a fact. You should find out whether your local laws permit this kind of copying for personal use, and make your own informed decision about whether it's wise to do so.)
If you intend to sell your poster, though, or even distribute it for free, I'd strongly advise against it — if for no other reason, then because the image you linked to looks very much like something that National Geographic might want to sell as a poster themselves. That might significantly increase their motivation to sue you if they find you stealing their potential profits.
Ps. It turns out that the image is for sale as a poster at least here and here. I had no luck with any of the obvious searches, but then I thought to try the artist's name plus "poster".