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Change input into centroids.

release/4.3a0
alexma3312 2020-09-26 12:13:40 -04:00
parent 933565c045
commit e12d3ba197
1 changed files with 11 additions and 16 deletions
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27
gtsam_unstable/geometry/Similarity3.cpp
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@ -25,13 +25,11 @@ namespace gtsam {
namespace{ namespace{
/// Subtract centroids from point pairs. /// Subtract centroids from point pairs.
static std::vector<Point3Pair> subtractCentroids(const std::vector<Point3Pair>& abPointPairs, const Point3& aCentroid, const Point3& bCentroid) { static std::vector<Point3Pair> subtractCentroids(const std::vector<Point3Pair>& abPointPairs, const Point3Pair& centroids) {
std::vector<Point3Pair> d_abPointPairs; std::vector<Point3Pair> d_abPointPairs;
Point3 aPoint, bPoint;
for (const Point3Pair& abPair : abPointPairs) { for (const Point3Pair& abPair : abPointPairs) {
std::tie(aPoint, bPoint) = abPair; Point3 da = abPair.first - centroids.first;
Point3 da = aPoint - aCentroid; Point3 db = abPair.second - centroids.second;
Point3 db = bPoint - bCentroid;
d_abPointPairs.emplace_back(da, db); d_abPointPairs.emplace_back(da, db);
} }
return d_abPointPairs; return d_abPointPairs;
@ -63,22 +61,20 @@ namespace{
} }
/// This method estimates the similarity transform from differences point pairs, given a known or estimated rotation and point centroids. /// This method estimates the similarity transform from differences point pairs, given a known or estimated rotation and point centroids.
static Similarity3 align(const std::vector<Point3Pair>& d_abPointPairs, const Rot3& aRb, const Point3& aCentroid, const Point3& bCentroid) { static Similarity3 align(const std::vector<Point3Pair>& d_abPointPairs, const Rot3& aRb, const Point3Pair& centroids) {
const double s = calculateScale(d_abPointPairs, aRb); const double s = calculateScale(d_abPointPairs, aRb);
// calculate translation // calculate translation
const Point3 aTb = (aCentroid - s * (aRb * bCentroid)) / s; const Point3 aTb = (centroids.first - s * (aRb * centroids.second)) / s;
return Similarity3(aRb, aTb, s); return Similarity3(aRb, aTb, s);
} }
/// This method estimates the similarity transform from point pairs, given a known or estimated rotation. /// This method estimates the similarity transform from point pairs, given a known or estimated rotation.
static Similarity3 alignGivenR(const std::vector<Point3Pair>& abPointPairs, const Rot3& aRb) { static Similarity3 alignGivenR(const std::vector<Point3Pair>& abPointPairs, const Rot3& aRb) {
// Refer to: http://www5.informatik.uni-erlangen.de/Forschung/Publikationen/2005/Zinsser05-PSR.pdf Chapter 3 // Refer to: http://www5.informatik.uni-erlangen.de/Forschung/Publikationen/2005/Zinsser05-PSR.pdf Chapter 3
// calculate centroids auto centroids = mean(abPointPairs);
Point3 aCentroid, bCentroid;
std::tie(aCentroid, bCentroid) = mean(abPointPairs);
// substract centroids // substract centroids
std::vector<Point3Pair> d_abPointPairs = subtractCentroids(abPointPairs, aCentroid, bCentroid); std::vector<Point3Pair> d_abPointPairs = subtractCentroids(abPointPairs, centroids);
return align(d_abPointPairs, aRb, aCentroid, bCentroid); return align(d_abPointPairs, aRb, centroids);
} }
} }
@ -161,15 +157,14 @@ Similarity3 Similarity3::Align(const std::vector<Point3Pair>& abPointPairs) {
const size_t n = abPointPairs.size(); const size_t n = abPointPairs.size();
if (n < 3) throw std::runtime_error("input should have at least 3 pairs of points"); // we need at least three pairs if (n < 3) throw std::runtime_error("input should have at least 3 pairs of points"); // we need at least three pairs
// calculate centroids // calculate centroids
Point3 aCentroid, bCentroid; auto centroids = mean(abPointPairs);
std::tie(aCentroid, bCentroid) = mean(abPointPairs);
// substract centroids // substract centroids
std::vector<Point3Pair> d_abPointPairs = subtractCentroids(abPointPairs, aCentroid, bCentroid); std::vector<Point3Pair> d_abPointPairs = subtractCentroids(abPointPairs, centroids);
// form H matrix // form H matrix
Matrix3 H = calculateH(d_abPointPairs); Matrix3 H = calculateH(d_abPointPairs);
// ClosestTo finds rotation matrix closest to H in Frobenius sense // ClosestTo finds rotation matrix closest to H in Frobenius sense
Rot3 aRb = Rot3::ClosestTo(H); Rot3 aRb = Rot3::ClosestTo(H);
return align(d_abPointPairs, aRb, aCentroid, bCentroid); return align(d_abPointPairs, aRb, centroids);
} }
Similarity3 Similarity3::Align(const std::vector<Pose3Pair>& abPosePairs) { Similarity3 Similarity3::Align(const std::vector<Pose3Pair>& abPosePairs) {