| // 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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| // this list of conditions and the following disclaimer in the documentation |
| // and/or other materials provided with the distribution. |
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| // 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 |
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| // |
| // 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_ |
