| // Ceres Solver - A fast non-linear least squares minimizer | |
| // Copyright 2023 Google Inc. All rights reserved. | |
| // http://ceres-solver.org/ | |
| // | |
| // Redistribution and use in source and binary forms, with or without | |
| // modification, are permitted provided that the following conditions are met: | |
| // | |
| // * Redistributions of source code must retain the above copyright notice, | |
| // this list of conditions and the following disclaimer. | |
| // * Redistributions in binary form must reproduce the above copyright notice, | |
| // this list of conditions and the following disclaimer in the documentation | |
| // and/or other materials provided with the distribution. | |
| // * Neither the name of Google Inc. nor the names of its contributors may be | |
| // used to endorse or promote products derived from this software without | |
| // specific prior written permission. | |
| // | |
| // THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" | |
| // AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE | |
| // IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE | |
| // ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE | |
| // LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR | |
| // CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF | |
| // SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS | |
| // INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN | |
| // CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) | |
| // ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE | |
| // POSSIBILITY OF SUCH DAMAGE. | |
| // | |
| // Author: kushalav@google.com (Avanish Kushal) | |
| // sameeragarwal@google.com (Sameer Agarwal) | |
| // | |
| // Functions to manipulate visibility information from the block | |
| // structure of sparse matrices. | |
| #ifndef CERES_INTERNAL_VISIBILITY_H_ | |
| #define CERES_INTERNAL_VISIBILITY_H_ | |
| #include <memory> | |
| #include <vector> | |
| #include "absl/container/btree_set.h" | |
| #include "ceres/graph.h" | |
| #include "ceres/internal/disable_warnings.h" | |
| #include "ceres/internal/export.h" | |
| namespace ceres::internal { | |
| struct CompressedRowBlockStructure; | |
| // Given a compressed row block structure, computes the set of | |
| // e_blocks "visible" to each f_block. If an e_block co-occurs with an | |
| // f_block in a residual block, it is visible to the f_block. The | |
| // first num_eliminate_blocks columns blocks are e_blocks and the rest | |
| // f_blocks. | |
| // | |
| // In a structure from motion problem, e_blocks correspond to 3D | |
| // points and f_blocks correspond to cameras. | |
| CERES_NO_EXPORT void ComputeVisibility( | |
| const CompressedRowBlockStructure& block_structure, | |
| int num_eliminate_blocks, | |
| std::vector<absl::btree_set<int>>* visibility); | |
| // Given f_block visibility as computed by the ComputeVisibility | |
| // function above, construct and return a graph whose vertices are | |
| // f_blocks and an edge connects two vertices if they have at least one | |
| // e_block in common. The weight of this edge is normalized dot | |
| // product between the visibility vectors of the two | |
| // vertices/f_blocks. | |
| // | |
| // This graph reflects the sparsity structure of reduced camera | |
| // matrix/Schur complement matrix obtained by eliminating the e_blocks | |
| // from the normal equations. | |
| // | |
| // Caller acquires ownership of the returned WeightedGraph pointer | |
| // (heap-allocated). | |
| CERES_NO_EXPORT std::unique_ptr<WeightedGraph<int>> CreateSchurComplementGraph( | |
| const std::vector<absl::btree_set<int>>& visibility); | |
| } // namespace ceres::internal | |
| #include "ceres/internal/reenable_warnings.h" | |
| #endif // CERES_INTERNAL_VISIBILITY_H_ |