quadmap

README

quadmap

Quadtree (kind of) using quad indexes instead of true tree

Based off an idea from https://learn.microsoft.com/en-us/bingmaps/articles/bing-maps-tile-system?redirectedfrom=MSDN

Notes

Now includes the bulk of the non-quadkey data in sqlite database. This is to test if the performance of shifting data to sqlite is bad enough to skip this experiment.

PLAN

• Overall aim is to determine if AOI overlaps any of the tiles in the quadmap.
• Get cover quadkeys for AOI
• If we have a large quadkey ... then can we still check the quadmap for that quadkey even if the real entry is for a smaller quadkey? (ie have zoom 18 but in the quadmap we have zoom 20). If we start search at larger quadkey
• AOI is converted into cover quadkeys... then reduced to the smallest possible quadkey (22?)
• Search quadmap for the appropriate quadkeys... increasing quadkey depth until level 14?

TODO

• Determine eviction/LRU policy. (evict tiles greater than a particular depth)
  • Will need to remove entries from Tile.groups
  • Reset watermark when removing particular entries

MISC

• Get tile that covers AOI
• then get all surveys within that tile.... <- tricky bit.
• perform geom intersection