4 ms·
The thing about SFC addressing is that two places near each other always share a prefix, and the closer they are, the longer the common prefix. It's sort of lik
by Sharlin 2y ago
The thing about SFC addressing is that two places near each other always share a prefix, and the closer they are, the longer the common prefix. It's sort of like Gray coding. Quadtree addressing, for example, also has the property that you mentioned (as do, of course, normal lat/long coordinates!) but two adjacent locations may not have similar addresses at all if they happen to straddle a subdivision boundary. (Again, compare to "normal" numbers where, say, |2000-1999| = 1 but there's no common prefix at all!)
- tomsmeding 2y agoThe same happens, in fact, for space-filling curves. Sure, in _most_ of the area covered by the curve, closeness of points means closeness on the curve. But in this Hilbert curve: https://upload.wikimedia.org/wikipedia/commons/7/7c/Hilbert-curve_rounded-gradient-animated.gif https://upload.wikimedia.org/wikipedia/commons/7/7c/Hilbert-... Consider the two points on the curve straddling the middle of the top edge of the square. They are very close together, but their 1D addresses on the curve are very far apart (one close-ish to the beginning, and one close-ish to the end)! There ain't no free lunch.
- Sharlin 2y agoYes, you’re right, of course.
- kittoes 2y agoThe boustrophedonic version of Rosenberg-Strong function is my favorite because it doesn't have any such jumps and has better locality preserving qualities than most alternatives. See https://hbfs.wordpress.com/2018/08/07/moeud-deux/ https://hbfs.wordpress.com/2018/08/07/moeud-deux/.