Calculate the Hilbert value of a point for use in a Hilbert R-Tree?

Question

I have an application where a Hilbert R-Tree (wikipedia) (citeseer) would seem to be an appropriate data structure. Specifically, it requires reasonably fast spatial querie

Answer 1

Michael,

thanks for your Java code! I tested it and it seems to work fine, but I noticed that the bit-interleaving function overflows at recursion level 7 (at least in my tests, but I used long values), because the "n"-value is calculated using highestOneBit()-function, which returns the value and not the position of the highest one bit; so the loop does unnecessarily many interleavings.

I just changed it to the following snippet, and after that it worked fine.

  int max = Math.max(odd, even);
  int n = 0;
  while (max > 0) {
    n++;
    max >>= 1;
  }