// Perform simple feature matching. This just uses the SSD
// distance between two feature vectors, and matches a feature in the
// first image with the closest feature in the second image. It can
// match multiple features in the first image to the same feature in
// the second image.
void ssdMatchFeatures(const FeatureSet &f1, const FeatureSet &f2, vector<FeatureMatch> &matches, double &totalScore) {
int m = f1.size();
int n = f2.size();
matches.resize(m);
totalScore = 0;
double d;
double dBest;
int idBest;
for (int i=0; i<m; i++) {
dBest = 1e100;
idBest = 0;
for (int j=0; j<n; j++) {
d = distanceSSD(f1[i].data, f2[j].data);
if (d < dBest) {
dBest = d;
idBest = f2[j].id;
}
}
matches[i].id1 = f1[i].id;
matches[i].id2 = idBest;
matches[i].score = dBest;
totalScore += matches[i].score;
}
}
// Perform ratio feature matching. This just uses the ratio of the SSD distance of the
// two best matches and matches a feature in the first image with the closest feature
// in the second image. It can match multiple features in the first image to the same
// feature in the second image.
void ratioMatchFeatures(const FeatureSet &f1, const FeatureSet &f2, vector<FeatureMatch> &matches)
{
int m = f1.size();
int n = f2.size();
matches.resize(m);
double d;
double dBest, dBest2;
int idBest;
for (int i=0; i<m; i++) {
dBest = 1e100;
dBest2 = 1e100;
idBest = 0;
for (int j=0; j<n; j++) {
d = distanceSSD(f1[i].data, f2[j].data);
if (d < dBest) {
dBest2 = dBest;
dBest = d;
idBest = f2[j].id;
}
else if (d < dBest2) {
dBest2 = d;
}
}
matches[i].id1 = f1[i].id;
matches[i].id2 = idBest;
matches[i].distance = dBest/dBest2;
}
}
