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// Ceres Solver - A fast non-linear least squares minimizer
// Copyright 2010, 2011, 2012 Google Inc. All rights reserved.
// http://code.google.com/p/ceres-solver/
//
// 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
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// ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
// POSSIBILITY OF SUCH DAMAGE.
//
// Author: sameeragarwal@google.com (Sameer Agarwal)
#include "ceres/parameter_block_ordering.h"
#include "ceres/graph.h"
#include "ceres/graph_algorithms.h"
#include "ceres/internal/scoped_ptr.h"
#include "ceres/map_util.h"
#include "ceres/parameter_block.h"
#include "ceres/program.h"
#include "ceres/residual_block.h"
#include "glog/logging.h"
namespace ceres {
namespace internal {
int ComputeStableSchurOrdering(const Program& program,
vector<ParameterBlock*>* ordering) {
CHECK_NOTNULL(ordering)->clear();
scoped_ptr<Graph< ParameterBlock*> > graph(CreateHessianGraph(program));
const vector<ParameterBlock*>& parameter_blocks = program.parameter_blocks();
const HashSet<ParameterBlock*>& vertices = graph->vertices();
for (int i = 0; i < parameter_blocks.size(); ++i) {
if (vertices.count(parameter_blocks[i]) > 0) {
ordering->push_back(parameter_blocks[i]);
}
}
int independent_set_size = StableIndependentSetOrdering(*graph, ordering);
// Add the excluded blocks to back of the ordering vector.
for (int i = 0; i < parameter_blocks.size(); ++i) {
ParameterBlock* parameter_block = parameter_blocks[i];
if (parameter_block->IsConstant()) {
ordering->push_back(parameter_block);
}
}
return independent_set_size;
}
int ComputeSchurOrdering(const Program& program,
vector<ParameterBlock*>* ordering) {
CHECK_NOTNULL(ordering)->clear();
scoped_ptr<Graph< ParameterBlock*> > graph(CreateHessianGraph(program));
int independent_set_size = IndependentSetOrdering(*graph, ordering);
const vector<ParameterBlock*>& parameter_blocks = program.parameter_blocks();
// Add the excluded blocks to back of the ordering vector.
for (int i = 0; i < parameter_blocks.size(); ++i) {
ParameterBlock* parameter_block = parameter_blocks[i];
if (parameter_block->IsConstant()) {
ordering->push_back(parameter_block);
}
}
return independent_set_size;
}
void ComputeRecursiveIndependentSetOrdering(const Program& program,
ParameterBlockOrdering* ordering) {
CHECK_NOTNULL(ordering)->Clear();
const vector<ParameterBlock*> parameter_blocks = program.parameter_blocks();
scoped_ptr<Graph< ParameterBlock*> > graph(CreateHessianGraph(program));
int num_covered = 0;
int round = 0;
while (num_covered < parameter_blocks.size()) {
vector<ParameterBlock*> independent_set_ordering;
const int independent_set_size =
IndependentSetOrdering(*graph, &independent_set_ordering);
for (int i = 0; i < independent_set_size; ++i) {
ParameterBlock* parameter_block = independent_set_ordering[i];
ordering->AddElementToGroup(parameter_block->mutable_user_state(), round);
graph->RemoveVertex(parameter_block);
}
num_covered += independent_set_size;
++round;
}
}
Graph<ParameterBlock*>*
CreateHessianGraph(const Program& program) {
Graph<ParameterBlock*>* graph = CHECK_NOTNULL(new Graph<ParameterBlock*>);
const vector<ParameterBlock*>& parameter_blocks = program.parameter_blocks();
for (int i = 0; i < parameter_blocks.size(); ++i) {
ParameterBlock* parameter_block = parameter_blocks[i];
if (!parameter_block->IsConstant()) {
graph->AddVertex(parameter_block);
}
}
const vector<ResidualBlock*>& residual_blocks = program.residual_blocks();
for (int i = 0; i < residual_blocks.size(); ++i) {
const ResidualBlock* residual_block = residual_blocks[i];
const int num_parameter_blocks = residual_block->NumParameterBlocks();
ParameterBlock* const* parameter_blocks =
residual_block->parameter_blocks();
for (int j = 0; j < num_parameter_blocks; ++j) {
if (parameter_blocks[j]->IsConstant()) {
continue;
}
for (int k = j + 1; k < num_parameter_blocks; ++k) {
if (parameter_blocks[k]->IsConstant()) {
continue;
}
graph->AddEdge(parameter_blocks[j], parameter_blocks[k]);
}
}
}
return graph;
}
} // namespace internal
} // namespace ceres