IEnumerable<MinutiaPair> GetRoots()
{
const int minEdgeLength = 58;
const int maxEdgeLookups = 1633;
int counter = 0;
var filters = new Predicate<EdgeShape>[]
{
shape => shape.Length >= minEdgeLength,
shape => shape.Length < minEdgeLength
};
foreach (var shapeFilter in filters)
{
for (int step = 1; step < Candidate.Minutiae.Count; ++step)
for (int pass = 0; pass < step + 1; ++pass)
for (int candidateReference = pass; candidateReference < Candidate.Minutiae.Count; candidateReference += step + 1)
{
int candidateNeighbor = (candidateReference + step) % Candidate.Minutiae.Count;
var candidateEdge = new EdgeShape(Candidate, candidateReference, candidateNeighbor);
if (shapeFilter(candidateEdge))
{
List<IndexedEdge> matches;
if (EdgeHash.TryGetValue(HashShape(candidateEdge), out matches))
{
foreach (var match in matches)
{
if (MatchingShapes(match.Shape, candidateEdge))
{
var pair = new MinutiaPair()
{
Probe = match.Reference,
Candidate = candidateReference
};
yield return pair;
++counter;
if (counter >= maxEdgeLookups)
yield break;
}
}
}
}
}
}
}
static int HashShape(EdgeShape edge)
{
return((edge.ReferenceAngle / MaxAngleError << 24) + (edge.NeighborAngle / MaxAngleError << 16) + edge.Length / MaxDistanceError);
}
double ComputeScore()
{
const int minSupportingEdges = 1;
const double distanceErrorFlatness = 0.69;
const double angleErrorFlatness = 0.27;
const double pairCountFactor = 0.032;
const double pairFractionFactor = 8.98;
const double correctTypeFactor = 0.629;
const double supportedCountFactor = 0.193;
const double edgeCountFactor = 0.265;
const double distanceAccuracyFactor = 9.9;
const double angleAccuracyFactor = 2.79;
double score = pairCountFactor * PairCount;
score += pairFractionFactor * (PairCount / (double)Template.Minutiae.Count + PairCount / (double)Candidate.Minutiae.Count) / 2;
for (int i = 0; i < PairCount; ++i)
{
PairInfo pair = PairList[i];
if (pair.SupportingEdges >= minSupportingEdges)
score += supportedCountFactor;
score += edgeCountFactor * (pair.SupportingEdges + 1);
if (Template.Minutiae[pair.Pair.Probe].Type == Candidate.Minutiae[pair.Pair.Candidate].Type)
score += correctTypeFactor;
}
var innerDistanceRadius = Convert.ToInt32(distanceErrorFlatness * FingerprintMatcher.MaxDistanceError);
var innerAngleRadius = Convert.ToInt32(angleErrorFlatness * FingerprintMatcher.MaxAngleError);
var distanceErrorSum = 0;
var angleErrorSum = 0;
for (int i = 1; i < PairCount; ++i)
{
PairInfo pair = PairList[i];
var probeEdge = new EdgeShape(Template, pair.Reference.Probe, pair.Pair.Probe);
var candidateEdge = new EdgeShape(Candidate, pair.Reference.Candidate, pair.Pair.Candidate);
distanceErrorSum += Math.Abs(probeEdge.Length - candidateEdge.Length);
angleErrorSum += Math.Max(innerDistanceRadius, Angle.Distance(probeEdge.ReferenceAngle, candidateEdge.ReferenceAngle));
angleErrorSum += Math.Max(innerAngleRadius, Angle.Distance(probeEdge.NeighborAngle, candidateEdge.NeighborAngle));
}
if (PairCount >= 2)
{
var maxDistanceError = FingerprintMatcher.MaxDistanceError * (PairCount - 1);
score += distanceAccuracyFactor * (maxDistanceError - distanceErrorSum) / maxDistanceError;
var maxAngleError = FingerprintMatcher.MaxAngleError * (PairCount - 1) * 2;
score += angleAccuracyFactor * (maxAngleError - angleErrorSum) / maxAngleError;
}
return score;
}
static bool MatchingShapes(EdgeShape probe, EdgeShape candidate)
{
int lengthDelta = probe.Length - candidate.Length;
if (lengthDelta >= -MaxDistanceError && lengthDelta <= MaxDistanceError)
{
byte complementaryAngleError = Angle.Complementary(MaxAngleError);
byte referenceDelta = Angle.Difference(probe.ReferenceAngle, candidate.ReferenceAngle);
if (referenceDelta <= MaxAngleError || referenceDelta >= complementaryAngleError)
{
byte neighborDelta = Angle.Difference(probe.NeighborAngle, candidate.NeighborAngle);
if (neighborDelta <= MaxAngleError || neighborDelta >= complementaryAngleError)
return true;
}
}
return false;
}
static int HashShape(EdgeShape edge)
{
return (edge.ReferenceAngle / MaxAngleError << 24) + (edge.NeighborAngle / MaxAngleError << 16) + edge.Length / MaxDistanceError;
}
static IEnumerable<int> GetShapeCoverage(EdgeShape edge)
{
int minLengthBin = (edge.Length - MaxDistanceError) / MaxDistanceError;
int maxLengthBin = (edge.Length + MaxDistanceError) / MaxDistanceError;
int angleBins = MathEx.DivRoundUp(256, MaxAngleError);
int minReferenceBin = Angle.Difference(edge.ReferenceAngle, MaxAngleError) / MaxAngleError;
int maxReferenceBin = Angle.Add(edge.ReferenceAngle, MaxAngleError) / MaxAngleError;
int endReferenceBin = (maxReferenceBin + 1) % angleBins;
int minNeighborBin = Angle.Difference(edge.NeighborAngle, MaxAngleError) / MaxAngleError;
int maxNeighborBin = Angle.Add(edge.NeighborAngle, MaxAngleError) / MaxAngleError;
int endNeighborBin = (maxNeighborBin + 1) % angleBins;
for (int lengthBin = minLengthBin; lengthBin <= maxLengthBin; ++lengthBin)
for (int referenceBin = minReferenceBin; referenceBin != endReferenceBin; referenceBin = (referenceBin + 1) % angleBins)
for (int neighborBin = minNeighborBin; neighborBin != endNeighborBin; neighborBin = (neighborBin + 1) % angleBins)
yield return (referenceBin << 24) + (neighborBin << 16) + lengthBin;
}
public void Compute(MatcherThread thread)
{
MinutiaCount = thread.Count;
MinutiaScore = Parameters.MinutiaScore * MinutiaCount;
MinutiaFractionInProbe = thread.Count / (double)thread.Probe.Minutiae.Length;
MinutiaFractionInCandidate = thread.Count / (double)thread.Candidate.Minutiae.Length;
MinutiaFraction = 0.5 * (MinutiaFractionInProbe + MinutiaFractionInCandidate);
MinutiaFractionScore = Parameters.MinutiaFractionScore * MinutiaFraction;
SupportingEdgeSum = 0;
SupportedMinutiaCount = 0;
MinutiaTypeHits = 0;
for (int i = 0; i < thread.Count; ++i)
{
var pair = thread.Tree[i];
SupportingEdgeSum += pair.SupportingEdges;
if (pair.SupportingEdges >= Parameters.MinSupportingEdges)
{
++SupportedMinutiaCount;
}
if (thread.Probe.Minutiae[pair.Probe].Type == thread.Candidate.Minutiae[pair.Candidate].Type)
{
++MinutiaTypeHits;
}
}
EdgeCount = thread.Count + SupportingEdgeSum;
EdgeScore = Parameters.EdgeScore * EdgeCount;
SupportedMinutiaScore = Parameters.SupportedMinutiaScore * SupportedMinutiaCount;
MinutiaTypeScore = Parameters.MinutiaTypeScore * MinutiaTypeHits;
int innerDistanceRadius = Doubles.RoundToInt(Parameters.DistanceErrorFlatness * Parameters.MaxDistanceError);
double innerAngleRadius = Parameters.AngleErrorFlatness * Parameters.MaxAngleError;
DistanceErrorSum = 0;
AngleErrorSum = 0;
for (int i = 1; i < thread.Count; ++i)
{
var pair = thread.Tree[i];
var probeEdge = new EdgeShape(thread.Probe.Minutiae[pair.ProbeRef], thread.Probe.Minutiae[pair.Probe]);
var candidateEdge = new EdgeShape(thread.Candidate.Minutiae[pair.CandidateRef], thread.Candidate.Minutiae[pair.Candidate]);
DistanceErrorSum += Math.Max(innerDistanceRadius, Math.Abs(probeEdge.Length - candidateEdge.Length));
AngleErrorSum += Math.Max(innerAngleRadius, DoubleAngle.Distance(probeEdge.ReferenceAngle, candidateEdge.ReferenceAngle));
AngleErrorSum += Math.Max(innerAngleRadius, DoubleAngle.Distance(probeEdge.NeighborAngle, candidateEdge.NeighborAngle));
}
DistanceAccuracyScore = 0;
AngleAccuracyScore = 0;
int distanceErrorPotential = Parameters.MaxDistanceError * Math.Max(0, thread.Count - 1);
DistanceAccuracySum = distanceErrorPotential - DistanceErrorSum;
DistanceAccuracyScore = Parameters.DistanceAccuracyScore * (distanceErrorPotential > 0 ? DistanceAccuracySum / (double)distanceErrorPotential : 0);
double angleErrorPotential = Parameters.MaxAngleError * Math.Max(0, thread.Count - 1) * 2;
AngleAccuracySum = angleErrorPotential - AngleErrorSum;
AngleAccuracyScore = Parameters.AngleAccuracyScore * (angleErrorPotential > 0 ? AngleAccuracySum / angleErrorPotential : 0);
TotalScore = MinutiaScore
+ MinutiaFractionScore
+ SupportedMinutiaScore
+ EdgeScore
+ MinutiaTypeScore
+ DistanceAccuracyScore
+ AngleAccuracyScore;
ShapedScore = Shape(TotalScore);
}
