[LUCENE-7270] Use better balanced trees for Geo3d complex polygons

• Type: Improvement
• Status: Resolved
• Priority: Major
• Resolution: Fixed
• Fix Version/s: 6.0
• Component/s: modules/spatial3d
• Lucene Fields: New
• Assignee: Karl Wright
• Reporter: Karl Wright
• Created: 03/May/16 12:59
• Updated: 28/Aug/22 14:57
• Resolved: 03/May/16 17:20

Description

The current tree data structure in GeoComplexPolygon has a lot of weaknesses. A better algorithm maybe can be taken from Polygon2D, which basically does the following:

Each node has:

• low value (which is for that edge alone)
• max value (which is for that edge and all children)

Balanced tree building:

• sort by low value (which is for the individual edge), and use max value as tie breaker (which is max for edge and all children)
• build tree after sorting, picking midpoint and recursively building lesser and greater children that way

Balanced tree traversal (looking for range minValue -> maxValue):

• Descend the entire tree until the node fails this test:
  if (minValue <= max) { ... }

  So if the minimum value being sought is greater than the max for this edge and all children, we stop and don't look at children.
  (Q: does this represent a good split and a targeted range? Maybe... We can certainly try it.)