|  | // Ceres Solver - A fast non-linear least squares minimizer | 
|  | // Copyright 2023 Google Inc. All rights reserved. | 
|  | // http://ceres-solver.org/ | 
|  | // | 
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|  | // modification, are permitted provided that the following conditions are met: | 
|  | // | 
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|  | // | 
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|  | // | 
|  | // Author: sameeragarwal@google.com (Sameer Agarwal) | 
|  |  | 
|  | #include "ceres/visibility_based_preconditioner.h" | 
|  |  | 
|  | #include <memory> | 
|  |  | 
|  | #include "Eigen/Dense" | 
|  | #include "ceres/block_random_access_dense_matrix.h" | 
|  | #include "ceres/block_random_access_sparse_matrix.h" | 
|  | #include "ceres/block_sparse_matrix.h" | 
|  | #include "ceres/casts.h" | 
|  | #include "ceres/file.h" | 
|  | #include "ceres/internal/eigen.h" | 
|  | #include "ceres/linear_least_squares_problems.h" | 
|  | #include "ceres/schur_eliminator.h" | 
|  | #include "ceres/test_util.h" | 
|  | #include "ceres/types.h" | 
|  | #include "gtest/gtest.h" | 
|  |  | 
|  | namespace ceres::internal { | 
|  |  | 
|  | // TODO(sameeragarwal): Re-enable this test once serialization is | 
|  | // working again. | 
|  |  | 
|  | // using testing::AssertionResult; | 
|  | // using testing::AssertionSuccess; | 
|  | // using testing::AssertionFailure; | 
|  |  | 
|  | // static const double kTolerance = 1e-12; | 
|  |  | 
|  | // class VisibilityBasedPreconditionerTest : public ::testing::Test { | 
|  | //  public: | 
|  | //   static const int kCameraSize = 9; | 
|  |  | 
|  | //  protected: | 
|  | //   void SetUp() { | 
|  | //     string input_file = TestFileAbsolutePath("problem-6-1384-000.lsqp"); | 
|  |  | 
|  | //     std::unique_ptr<LinearLeastSquaresProblem> problem = | 
|  | //     CreateLinearLeastSquaresProblemFromFile(input_file)); | 
|  | //     A_.reset(down_cast<BlockSparseMatrix*>(problem->A.release())); | 
|  | //     b_.reset(problem->b.release()); | 
|  | //     D_.reset(problem->D.release()); | 
|  |  | 
|  | //     const CompressedRowBlockStructure* bs = | 
|  | //         ASSERT_TRUE(A_->block_structure()!=nullptr); | 
|  | //     const int num_col_blocks = bs->cols.size(); | 
|  |  | 
|  | //     num_cols_ = A_->num_cols(); | 
|  | //     num_rows_ = A_->num_rows(); | 
|  | //     num_eliminate_blocks_ = problem->num_eliminate_blocks; | 
|  | //     num_camera_blocks_ = num_col_blocks - num_eliminate_blocks_; | 
|  | //     options_.elimination_groups.push_back(num_eliminate_blocks_); | 
|  | //     options_.elimination_groups.push_back( | 
|  | //         A_->block_structure()->cols.size() - num_eliminate_blocks_); | 
|  |  | 
|  | //     vector<int> blocks(num_col_blocks - num_eliminate_blocks_, 0); | 
|  | //     for (int i = num_eliminate_blocks_; i < num_col_blocks; ++i) { | 
|  | //       blocks[i - num_eliminate_blocks_] = bs->cols[i].size; | 
|  | //     } | 
|  |  | 
|  | //     // The input matrix is a real jacobian and fairly poorly | 
|  | //     // conditioned. Setting D to a large constant makes the normal | 
|  | //     // equations better conditioned and makes the tests below better | 
|  | //     // conditioned. | 
|  | //     VectorRef(D_.get(), num_cols_).setConstant(10.0); | 
|  |  | 
|  | //     schur_complement_ = | 
|  | //     std::make_unique<BlockRandomAccessDenseMatrix>(blocks); | 
|  | //     Vector rhs(schur_complement_->num_rows()); | 
|  |  | 
|  | //     std::unique_ptr<SchurEliminatorBase> eliminator; | 
|  | //     LinearSolver::Options eliminator_options; | 
|  | //     eliminator_options.elimination_groups = options_.elimination_groups; | 
|  | //     eliminator_options.num_threads = options_.num_threads; | 
|  |  | 
|  | //     eliminator = SchurEliminatorBase::Create(eliminator_options); | 
|  | //     eliminator->Init(num_eliminate_blocks_, bs); | 
|  | //     eliminator->Eliminate(A_.get(), b_.get(), D_.get(), | 
|  | //                           schur_complement_.get(), rhs.data()); | 
|  | //   } | 
|  |  | 
|  | //   AssertionResult IsSparsityStructureValid() { | 
|  | //     preconditioner_->InitStorage(*A_->block_structure()); | 
|  | //     const absl::flat_hash_set<pair<int, int>>& cluster_pairs = | 
|  | //     get_cluster_pairs(); const vector<int>& cluster_membership = | 
|  | //     get_cluster_membership(); | 
|  |  | 
|  | //     for (int i = 0; i < num_camera_blocks_; ++i) { | 
|  | //       for (int j = i; j < num_camera_blocks_; ++j) { | 
|  | //         if (cluster_pairs.count(make_pair(cluster_membership[i], | 
|  | //                                           cluster_membership[j]))) { | 
|  | //           if (!IsBlockPairInPreconditioner(i, j)) { | 
|  | //             return AssertionFailure() | 
|  | //                 << "block pair (" << i << "," << j << "missing"; | 
|  | //           } | 
|  | //         } else { | 
|  | //           if (IsBlockPairInPreconditioner(i, j)) { | 
|  | //             return AssertionFailure() | 
|  | //                << "block pair (" << i << "," << j << "should not be present"; | 
|  | //           } | 
|  | //         } | 
|  | //       } | 
|  | //     } | 
|  | //     return AssertionSuccess(); | 
|  | //   } | 
|  |  | 
|  | //   AssertionResult PreconditionerValuesMatch() { | 
|  | //     preconditioner_->Update(*A_, D_.get()); | 
|  | //     const absl::flat_hash_set<pair<int, int>>& cluster_pairs = | 
|  | //     get_cluster_pairs(); const BlockRandomAccessSparseMatrix* m = get_m(); | 
|  | //     Matrix preconditioner_matrix; | 
|  | //     m->matrix()->ToDenseMatrix(&preconditioner_matrix); | 
|  | //     ConstMatrixRef full_schur_complement(schur_complement_->values(), | 
|  | //                                          m->num_rows(), | 
|  | //                                          m->num_rows()); | 
|  | //     const int num_clusters = get_num_clusters(); | 
|  | //     const int kDiagonalBlockSize = | 
|  | //         kCameraSize * num_camera_blocks_ / num_clusters; | 
|  |  | 
|  | //     for (int i = 0; i < num_clusters; ++i) { | 
|  | //       for (int j = i; j < num_clusters; ++j) { | 
|  | //         double diff = 0.0; | 
|  | //         if (cluster_pairs.count(make_pair(i, j))) { | 
|  | //           diff = | 
|  | //               (preconditioner_matrix.block(kDiagonalBlockSize * i, | 
|  | //                                            kDiagonalBlockSize * j, | 
|  | //                                            kDiagonalBlockSize, | 
|  | //                                            kDiagonalBlockSize) - | 
|  | //                full_schur_complement.block(kDiagonalBlockSize * i, | 
|  | //                                            kDiagonalBlockSize * j, | 
|  | //                                            kDiagonalBlockSize, | 
|  | //                                            kDiagonalBlockSize)).norm(); | 
|  | //         } else { | 
|  | //           diff = preconditioner_matrix.block(kDiagonalBlockSize * i, | 
|  | //                                              kDiagonalBlockSize * j, | 
|  | //                                              kDiagonalBlockSize, | 
|  | //                                              kDiagonalBlockSize).norm(); | 
|  | //         } | 
|  | //         if (diff > kTolerance) { | 
|  | //           return AssertionFailure() | 
|  | //               << "Preconditioner block " << i << " " << j << " differs " | 
|  | //               << "from expected value by " << diff; | 
|  | //         } | 
|  | //       } | 
|  | //     } | 
|  | //     return AssertionSuccess(); | 
|  | //   } | 
|  |  | 
|  | //   // Accessors | 
|  | //   int get_num_blocks() { return preconditioner_->num_blocks_; } | 
|  |  | 
|  | //   int get_num_clusters() { return preconditioner_->num_clusters_; } | 
|  | //   int* get_mutable_num_clusters() { return &preconditioner_->num_clusters_; } | 
|  |  | 
|  | //   const vector<int>& get_block_size() { | 
|  | //     return preconditioner_->block_size_; } | 
|  |  | 
|  | //   vector<int>* get_mutable_block_size() { | 
|  | //     return &preconditioner_->block_size_; } | 
|  |  | 
|  | //   const vector<int>& get_cluster_membership() { | 
|  | //     return preconditioner_->cluster_membership_; | 
|  | //   } | 
|  |  | 
|  | //   vector<int>* get_mutable_cluster_membership() { | 
|  | //     return &preconditioner_->cluster_membership_; | 
|  | //   } | 
|  |  | 
|  | //   const set<pair<int, int>>& get_block_pairs() { | 
|  | //     return preconditioner_->block_pairs_; | 
|  | //   } | 
|  |  | 
|  | //   set<pair<int, int>>* get_mutable_block_pairs() { | 
|  | //     return &preconditioner_->block_pairs_; | 
|  | //   } | 
|  |  | 
|  | //   const absl::flat_hash_set<pair<int, int>>& get_cluster_pairs() { | 
|  | //     return preconditioner_->cluster_pairs_; | 
|  | //   } | 
|  |  | 
|  | //   absl::flat_hash_set<pair<int, int>>* get_mutable_cluster_pairs() | 
|  | //   { | 
|  | //     return &preconditioner_->cluster_pairs_; | 
|  | //   } | 
|  |  | 
|  | //   bool IsBlockPairInPreconditioner(const int block1, const int block2) { | 
|  | //     return preconditioner_->IsBlockPairInPreconditioner(block1, block2); | 
|  | //   } | 
|  |  | 
|  | //   bool IsBlockPairOffDiagonal(const int block1, const int block2) { | 
|  | //     return preconditioner_->IsBlockPairOffDiagonal(block1, block2); | 
|  | //   } | 
|  |  | 
|  | //   const BlockRandomAccessSparseMatrix* get_m() { | 
|  | //     return preconditioner_->m_.get(); | 
|  | //   } | 
|  |  | 
|  | //   int num_rows_; | 
|  | //   int num_cols_; | 
|  | //   int num_eliminate_blocks_; | 
|  | //   int num_camera_blocks_; | 
|  |  | 
|  | //   std::unique_ptr<BlockSparseMatrix> A_; | 
|  | //   std::unique_ptr<double[]> b_; | 
|  | //   std::unique_ptr<double[]> D_; | 
|  |  | 
|  | //   Preconditioner::Options options_; | 
|  | //   std::unique_ptr<VisibilityBasedPreconditioner> preconditioner_; | 
|  | //   std::unique_ptr<BlockRandomAccessDenseMatrix> schur_complement_; | 
|  | // }; | 
|  |  | 
|  | // TEST_F(VisibilityBasedPreconditionerTest, OneClusterClusterJacobi) { | 
|  | //   options_.type = CLUSTER_JACOBI; | 
|  | //   preconditioner_ = | 
|  | //       std::make_unique<VisibilityBasedPreconditioner>( | 
|  | //          *A_->block_structure(), options_); | 
|  |  | 
|  | //   // Override the clustering to be a single clustering containing all | 
|  | //   // the cameras. | 
|  | //   vector<int>& cluster_membership = *get_mutable_cluster_membership(); | 
|  | //   for (int i = 0; i < num_camera_blocks_; ++i) { | 
|  | //     cluster_membership[i] = 0; | 
|  | //   } | 
|  |  | 
|  | //   *get_mutable_num_clusters() = 1; | 
|  |  | 
|  | //   absl::flat_hash_set<pair<int, int>>& cluster_pairs = | 
|  | //   *get_mutable_cluster_pairs(); cluster_pairs.clear(); | 
|  | //   cluster_pairs.insert(make_pair(0, 0)); | 
|  |  | 
|  | //   EXPECT_TRUE(IsSparsityStructureValid()); | 
|  | //   EXPECT_TRUE(PreconditionerValuesMatch()); | 
|  |  | 
|  | //   // Multiplication by the inverse of the preconditioner. | 
|  | //   const int num_rows = schur_complement_->num_rows(); | 
|  | //   ConstMatrixRef full_schur_complement(schur_complement_->values(), | 
|  | //                                        num_rows, | 
|  | //                                        num_rows); | 
|  | //   Vector x(num_rows); | 
|  | //   Vector y(num_rows); | 
|  | //   Vector z(num_rows); | 
|  |  | 
|  | //   for (int i = 0; i < num_rows; ++i) { | 
|  | //     x.setZero(); | 
|  | //     y.setZero(); | 
|  | //     z.setZero(); | 
|  | //     x[i] = 1.0; | 
|  | //     preconditioner_->RightMultiplyAndAccumulate(x.data(), y.data()); | 
|  | //     z = full_schur_complement | 
|  | //         .selfadjointView<Eigen::Upper>() | 
|  | //         .llt().solve(x); | 
|  | //     double max_relative_difference = | 
|  | //         ((y - z).array() / z.array()).matrix().lpNorm<Eigen::Infinity>(); | 
|  | //     EXPECT_NEAR(max_relative_difference, 0.0, kTolerance); | 
|  | //   } | 
|  | // } | 
|  |  | 
|  | // TEST_F(VisibilityBasedPreconditionerTest, ClusterJacobi) { | 
|  | //   options_.type = CLUSTER_JACOBI; | 
|  | //   preconditioner_ = | 
|  | //   std::make_unique<VisibilityBasedPreconditioner>(*A_->block_structure(), | 
|  | //   options_); | 
|  |  | 
|  | //   // Override the clustering to be equal number of cameras. | 
|  | //   vector<int>& cluster_membership = *get_mutable_cluster_membership(); | 
|  | //   cluster_membership.resize(num_camera_blocks_); | 
|  | //   static const int kNumClusters = 3; | 
|  |  | 
|  | //   for (int i = 0; i < num_camera_blocks_; ++i) { | 
|  | //     cluster_membership[i] = (i * kNumClusters) / num_camera_blocks_; | 
|  | //   } | 
|  | //   *get_mutable_num_clusters() = kNumClusters; | 
|  |  | 
|  | //   absl::flat_hash_set<pair<int, int>>& cluster_pairs = | 
|  | //   *get_mutable_cluster_pairs(); cluster_pairs.clear(); for (int i = 0; i < | 
|  | //   kNumClusters; ++i) { | 
|  | //     cluster_pairs.insert(make_pair(i, i)); | 
|  | //   } | 
|  |  | 
|  | //   EXPECT_TRUE(IsSparsityStructureValid()); | 
|  | //   EXPECT_TRUE(PreconditionerValuesMatch()); | 
|  | // } | 
|  |  | 
|  | // TEST_F(VisibilityBasedPreconditionerTest, ClusterTridiagonal) { | 
|  | //   options_.type = CLUSTER_TRIDIAGONAL; | 
|  | //   preconditioner_ = | 
|  | //     std::make_unique<VisibilityBasedPreconditioner>(*A_->block_structure(), | 
|  | //     options_); | 
|  | //   static const int kNumClusters = 3; | 
|  |  | 
|  | //   // Override the clustering to be 3 clusters. | 
|  | //   vector<int>& cluster_membership = *get_mutable_cluster_membership(); | 
|  | //   cluster_membership.resize(num_camera_blocks_); | 
|  | //   for (int i = 0; i < num_camera_blocks_; ++i) { | 
|  | //     cluster_membership[i] = (i * kNumClusters) / num_camera_blocks_; | 
|  | //   } | 
|  | //   *get_mutable_num_clusters() = kNumClusters; | 
|  |  | 
|  | //   // Spanning forest has structure 0-1 2 | 
|  | //   absl::flat_hash_set<pair<int, int>>& cluster_pairs = | 
|  | //   *get_mutable_cluster_pairs(); cluster_pairs.clear(); for (int i = 0; i < | 
|  | //   kNumClusters; ++i) { | 
|  | //     cluster_pairs.insert(make_pair(i, i)); | 
|  | //   } | 
|  | //   cluster_pairs.insert(make_pair(0, 1)); | 
|  |  | 
|  | //   EXPECT_TRUE(IsSparsityStructureValid()); | 
|  | //   EXPECT_TRUE(PreconditionerValuesMatch()); | 
|  | // } | 
|  |  | 
|  | }  // namespace ceres::internal |