1 // Ceres Solver - A fast non-linear least squares minimizer
2 // Copyright 2010, 2011, 2012 Google Inc. All rights reserved.
3 // http://code.google.com/p/ceres-solver/
4 //
5 // Redistribution and use in source and binary forms, with or without
6 // modification, are permitted provided that the following conditions are met:
7 //
8 // * Redistributions of source code must retain the above copyright notice,
9 // this list of conditions and the following disclaimer.
10 // * Redistributions in binary form must reproduce the above copyright notice,
11 // this list of conditions and the following disclaimer in the documentation
12 // and/or other materials provided with the distribution.
13 // * Neither the name of Google Inc. nor the names of its contributors may be
14 // used to endorse or promote products derived from this software without
15 // specific prior written permission.
16 //
17 // THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
18 // AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
19 // IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
20 // ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE
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24 // INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
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26 // ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
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28 //
29 // Author: sameeragarwal@google.com (Sameer Agarwal)
30
31 #include "ceres/schur_ordering.h"
32
33 #include "ceres/graph.h"
34 #include "ceres/graph_algorithms.h"
35 #include "ceres/internal/scoped_ptr.h"
36 #include "ceres/map_util.h"
37 #include "ceres/parameter_block.h"
38 #include "ceres/program.h"
39 #include "ceres/residual_block.h"
40 #include "glog/logging.h"
41
42 namespace ceres {
43 namespace internal {
44
ComputeSchurOrdering(const Program & program,vector<ParameterBlock * > * ordering)45 int ComputeSchurOrdering(const Program& program,
46 vector<ParameterBlock*>* ordering) {
47 CHECK_NOTNULL(ordering)->clear();
48
49 scoped_ptr<Graph< ParameterBlock*> > graph(
50 CHECK_NOTNULL(CreateHessianGraph(program)));
51 int independent_set_size = IndependentSetOrdering(*graph, ordering);
52 const vector<ParameterBlock*>& parameter_blocks = program.parameter_blocks();
53
54 // Add the excluded blocks to back of the ordering vector.
55 for (int i = 0; i < parameter_blocks.size(); ++i) {
56 ParameterBlock* parameter_block = parameter_blocks[i];
57 if (parameter_block->IsConstant()) {
58 ordering->push_back(parameter_block);
59 }
60 }
61
62 return independent_set_size;
63 }
64
65 Graph<ParameterBlock*>*
CreateHessianGraph(const Program & program)66 CreateHessianGraph(const Program& program) {
67 Graph<ParameterBlock*>* graph = new Graph<ParameterBlock*>;
68 const vector<ParameterBlock*>& parameter_blocks = program.parameter_blocks();
69 for (int i = 0; i < parameter_blocks.size(); ++i) {
70 ParameterBlock* parameter_block = parameter_blocks[i];
71 if (!parameter_block->IsConstant()) {
72 graph->AddVertex(parameter_block);
73 }
74 }
75
76 const vector<ResidualBlock*>& residual_blocks = program.residual_blocks();
77 for (int i = 0; i < residual_blocks.size(); ++i) {
78 const ResidualBlock* residual_block = residual_blocks[i];
79 const int num_parameter_blocks = residual_block->NumParameterBlocks();
80 ParameterBlock* const* parameter_blocks =
81 residual_block->parameter_blocks();
82 for (int j = 0; j < num_parameter_blocks; ++j) {
83 if (parameter_blocks[j]->IsConstant()) {
84 continue;
85 }
86
87 for (int k = j + 1; k < num_parameter_blocks; ++k) {
88 if (parameter_blocks[k]->IsConstant()) {
89 continue;
90 }
91
92 graph->AddEdge(parameter_blocks[j], parameter_blocks[k]);
93 }
94 }
95 }
96
97 return graph;
98 }
99
100 } // namespace internal
101 } // namespace ceres
102