PointToPointSimilarity.cpp
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3 /*
4 
5 Copyright (c) 2010--2012,
6 François Pomerleau and Stephane Magnenat, ASL, ETHZ, Switzerland
7 You can contact the authors at <f dot pomerleau at gmail dot com> and
8 <stephane at magnenat dot net>
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35 
36 #include "ErrorMinimizersImpl.h"
37 #include "PointMatcherPrivate.h"
38 #include "Eigen/SVD"
39 
40 using namespace Eigen;
41 
42 template<typename T>
44 {
45 
46  // Copy error element to use as storage later
47  // TODO: check that, might worth it to only copy useful parts
48  ErrorElements mPts = mPts_const;
49 
50  // now minimize on kept points
51  const int dimCount(mPts.reading.features.rows());
52  //const int ptsCount(mPts.reading.features.cols()); //Both point clouds have now the same number of (matched) point
53 
54 
55  // Compute the (weighted) mean of each point cloud
56  //TODO: change the member weights to be a Vector
57  const Vector w = mPts.weights.row(0);
58  const T w_sum_inv = T(1.)/w.sum();
59  const Vector meanReading =
60  (mPts.reading.features.topRows(dimCount-1).array().rowwise() * w.array().transpose()).rowwise().sum() * w_sum_inv;
61  const Vector meanReference =
62  (mPts.reference.features.topRows(dimCount-1).array().rowwise() * w.array().transpose()).rowwise().sum() * w_sum_inv;
63 
64 
65  // Remove the mean from the point clouds
66  mPts.reading.features.topRows(dimCount-1).colwise() -= meanReading;
67  mPts.reference.features.topRows(dimCount-1).colwise() -= meanReference;
68 
69  const T sigma = mPts.reading.features.topRows(dimCount-1).colwise().squaredNorm().cwiseProduct(w.transpose()).sum();
70 
71  // Singular Value Decomposition
72  const Matrix m(mPts.reference.features.topRows(dimCount-1) * w.asDiagonal()
73  * mPts.reading.features.topRows(dimCount-1).transpose());
74  const JacobiSVD<Matrix> svd(m, ComputeThinU | ComputeThinV);
75  Matrix rotMatrix(svd.matrixU() * svd.matrixV().transpose());
76  typedef typename JacobiSVD<Matrix>::SingularValuesType SingularValuesType;
77  SingularValuesType singularValues = svd.singularValues();
78  // It is possible to get a reflection instead of a rotation. In this case, we
79  // take the second best solution, guaranteed to be a rotation. For more details,
80  // read the tech report: "Least-Squares Rigid Motion Using SVD", Olga Sorkine
81  // http://igl.ethz.ch/projects/ARAP/svd_rot.pdf
82  if (rotMatrix.determinant() < 0.)
83  {
84  Matrix tmpV = svd.matrixV().transpose();
85  tmpV.row(dimCount-2) *= -1.;
86  rotMatrix = svd.matrixU() * tmpV;
87  singularValues(dimCount-2) *= -1.;
88  }
89  T scale = singularValues.sum() / sigma;
90  if (sigma < 0.0001) scale = T(1);
91  const Vector trVector(meanReference - scale * rotMatrix * meanReading);
92 
93  Matrix result(Matrix::Identity(dimCount, dimCount));
94  result.topLeftCorner(dimCount-1, dimCount-1) = scale * rotMatrix;
95  result.topRightCorner(dimCount-1, 1) = trVector;
96 
97  return result;
98 }
99 
100 template<typename T>
102  const DataPoints& filteredReading,
103  const DataPoints& filteredReference,
104  const OutlierWeights& outlierWeights,
105  const Matches& matches) const
106 {
107  assert(matches.ids.rows() > 0);
108 
109  // Fetch paired points
110  typename ErrorMinimizer::ErrorElements mPts(filteredReading, filteredReference, outlierWeights, matches);
111 
113 }
114 
115 template<typename T>
117 {
118  //NOTE: computing overlap of 2 point clouds can be complicated due to
119  // the sparse nature of the representation. Here is only an estimate
120  // of the true overlap.
121  const int nbPoints = this->lastErrorElements.reading.features.cols();
122  const int dim = this->lastErrorElements.reading.features.rows();
123  if(nbPoints == 0)
124  {
125  throw std::runtime_error("Error, last error element empty. Error minimizer needs to be called at least once before using this method.");
126  }
127 
128  if (!this->lastErrorElements.reading.descriptorExists("simpleSensorNoise"))
129  {
130  LOG_INFO_STREAM("PointToPointSimilarityErrorMinimizer - warning, no sensor noise found. Using best estimate given outlier rejection instead.");
131  return this->getWeightedPointUsedRatio();
132  }
133 
134  const BOOST_AUTO(noises, this->lastErrorElements.reading.getDescriptorViewByName("simpleSensorNoise"));
135 
136  const Vector dists = (this->lastErrorElements.reading.features.topRows(dim-1) - this->lastErrorElements.reference.features.topRows(dim-1)).colwise().norm();
137  const T mean = dists.sum()/nbPoints;
138 
139  int count = 0;
140  for(int i=0; i < nbPoints; i++)
141  {
142  if(dists(i) < (mean + noises(0,i)))
143  {
144  count++;
145  }
146  }
147 
148  return (T)count/(T)nbPoints;
149 }
150 
#define LOG_INFO_STREAM(args)
virtual T getResidualError(const DataPoints &filteredReading, const DataPoints &filteredReference, const OutlierWeights &outlierWeights, const Matches &matches) const
If not redefined by child class, return max value for T.
virtual T getOverlap() const
If not redefined by child class, return the ratio of how many points were used (with weight) for erro...
A structure holding data ready for minimization. The data are "normalized", for instance there are no...
Definition: PointMatcher.h:533
DataPoints reference
reference point cloud
Definition: PointMatcher.h:536
OutlierWeights weights
weights for every association
Definition: PointMatcher.h:537
Result of the data-association step (Matcher::findClosests), before outlier rejection.
Definition: PointMatcher.h:371
static T computeResidualError(const ErrorElements &mPts)
virtual TransformationParameters compute(const ErrorElements &mPts)
Find the transformation that minimizes the error given matched pair of points. This function most be ...
PointMatcher< T >::OutlierWeights OutlierWeights
Ids ids
identifiers of closest points
Definition: PointMatcher.h:385
Matrix features
features of points in the cloud
Definition: PointMatcher.h:331
DataPoints reading
reading point cloud
Definition: PointMatcher.h:535
Matrix TransformationParameters
A matrix holding the parameters a transformation.
Definition: PointMatcher.h:182


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autogenerated on Sat May 27 2023 02:38:03