1 // Ceres Solver - A fast non-linear least squares minimizer
2 // Copyright 2015 Google Inc. All rights reserved.
3 // http://ceres-solver.org/
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29 // Author: kushalav@google.com (Avanish Kushal)
30 // sameeragarwal@google.com (Sameer Agarwal)
32 // Functions to manipulate visibility information from the block
33 // structure of sparse matrices.
35 #ifndef CERES_INTERNAL_VISIBILITY_H_
36 #define CERES_INTERNAL_VISIBILITY_H_
40 #include "ceres/graph.h"
45 struct CompressedRowBlockStructure;
47 // Given a compressed row block structure, computes the set of
48 // e_blocks "visible" to each f_block. If an e_block co-occurs with an
49 // f_block in a residual block, it is visible to the f_block. The
50 // first num_eliminate_blocks columns blocks are e_blocks and the rest
53 // In a structure from motion problem, e_blocks correspond to 3D
54 // points and f_blocks correspond to cameras.
55 void ComputeVisibility(const CompressedRowBlockStructure& block_structure,
56 int num_eliminate_blocks,
57 std::vector<std::set<int> >* visibility);
59 // Given f_block visibility as computed by the ComputeVisibility
60 // function above, construct and return a graph whose vertices are
61 // f_blocks and an edge connects two vertices if they have atleast one
62 // e_block in common. The weight of this edge is normalized dot
63 // product between the visibility vectors of the two
66 // This graph reflects the sparsity structure of reduced camera
67 // matrix/Schur complement matrix obtained by eliminating the e_blocks
68 // from the normal equations.
70 // Caller acquires ownership of the returned WeightedGraph pointer
72 WeightedGraph<int>* CreateSchurComplementGraph(
73 const std::vector<std::set<int> >& visibility);
75 } // namespace internal
78 #endif // CERES_INTERNAL_VISIBILITY_H_