Parasitemia/ParasitemiaCore/MatchingEllipses.fs

   1 module ParasitemiaCore.MatchingEllipses
   2
   3 open System
   4 open System.Linq
   5 open System.Collections
   6 open System.Collections.Generic
   7
   8 open Types
   9 open Utils
  10
  11 type private EllipseScoreFlaggedKd (matchingScore: float32, e: Ellipse) =
  12     let mutable matchingScore = matchingScore
  13
  14     member this.Ellipse = e
  15
  16     member this.MatchingScore = matchingScore
  17
  18     member this.AddMatchingScore (score: float32) =
  19         matchingScore <- matchingScore + score
  20
  21     member val Processed = false with get, set
  22     member val Removed = false with get, set
  23
  24     interface KdTree.I2DCoords with
  25         member this.X = this.Ellipse.Cx
  26         member this.Y = this.Ellipse.Cy
  27
  28 type MatchingEllipses (radius: float32) =
  29     let ellipses = List<EllipseScoreFlaggedKd>()
  30
  31     // All ellipses with a score below this are removed.
  32     let matchingScoreThreshold = 0.8f
  33
  34     member this.Add (e: Ellipse) =
  35         ellipses.Add(EllipseScoreFlaggedKd(0.f, e))
  36
  37     member this.Ellipses : Ellipse list =
  38         List.ofSeq ellipses |> List.map (fun e -> e.Ellipse)
  39
  40     member this.PrunedEllipses : Ellipse list =
  41         if ellipses.Count = 0
  42         then
  43             []
  44         else
  45             // 1) Create a kd-tree from the ellipses list.
  46             let tree = KdTree.Tree.BuildTree (List.ofSeq ellipses)
  47
  48             // 2) Compute the matching score of each ellipses.
  49             let windowSize = radius / 2.f
  50             for e in ellipses do
  51                 e.Processed <- true
  52                 let areaE = e.Ellipse.Area
  53                 let window = { KdTree.minX = e.Ellipse.Cx - windowSize / 2.f
  54                                KdTree.maxX = e.Ellipse.Cx + windowSize / 2.f
  55                                KdTree.minY = e.Ellipse.Cy - windowSize / 2.f
  56                                KdTree.maxY = e.Ellipse.Cy + windowSize / 2.f }
  57                 for other in tree.Search window do
  58                     if not other.Processed
  59                     then
  60                         let areaOther = other.Ellipse.Area
  61                         match EEOver.EEOverlapArea e.Ellipse other.Ellipse with
  62                         | Some (overlapArea, _, _) ->
  63                             let matchingScore = (2.f * overlapArea / (areaE + areaOther)) ** 30.f
  64                             if matchingScore <= 1.f // For approximation error.
  65                             then
  66                                 other.AddMatchingScore(matchingScore)
  67                                 e.AddMatchingScore(matchingScore)
  68                         | _ -> ()
  69
  70             // 3) Remove ellipses whose center is near the center of another ellipse with a better score.
  71             for e in ellipses do
  72                 if e.MatchingScore < matchingScoreThreshold
  73                 then
  74                     e.Removed <- true
  75                 else
  76                     let window = { KdTree.minX = e.Ellipse.Cx - e.Ellipse.A
  77                                    KdTree.maxX = e.Ellipse.Cx + e.Ellipse.A
  78                                    KdTree.minY = e.Ellipse.Cy - e.Ellipse.A
  79                                    KdTree.maxY = e.Ellipse.Cy + e.Ellipse.A }
  80                     for other in tree.Search window do
  81                         if not other.Removed && e.MatchingScore > other.MatchingScore
  82                         then
  83                             // Case where ellipses are too close.
  84                             if distanceTwoPoints (PointD(e.Ellipse.Cx, e.Ellipse.Cy)) (PointD(other.Ellipse.Cx, other.Ellipse.Cy)) < 0.3f * e.Ellipse.B
  85                             then
  86                                 other.Removed <- true
  87                             else
  88                                 // Case where ellipses are overlapped.
  89                                 match EEOver.EEOverlapArea e.Ellipse other.Ellipse with
  90                                 | Some (overlapArea, _, _) when e.Ellipse.Area < 1.1f * overlapArea || other.Ellipse.Area < 1.1f * overlapArea ->
  91                                     other.Removed <- true
  92                                 | _ ->
  93                                     ()
  94
  95             ellipses
  96             |> List.ofSeq
  97             |> List.filter (fun e -> not e.Removed)
  98             |> List.sortWith (fun e1 e2 -> e2.MatchingScore.CompareTo(e1.MatchingScore))
  99             |> List.map (fun e -> e.Ellipse)
 100