Preconditioner refactoring.
1. Added a Preconditioner interface.
2. SCHUR_JACOBI is now its own class and is independent of
SuiteSparse.
Change-Id: Id912ab19cf3736e61d1b90ddaf5bfba33e877ec4
diff --git a/internal/ceres/visibility_based_preconditioner.cc b/internal/ceres/visibility_based_preconditioner.cc
index ae26d91..a75d6f0 100644
--- a/internal/ceres/visibility_based_preconditioner.cc
+++ b/internal/ceres/visibility_based_preconditioner.cc
@@ -65,17 +65,16 @@
#ifndef CERES_NO_SUITESPARSE
VisibilityBasedPreconditioner::VisibilityBasedPreconditioner(
const CompressedRowBlockStructure& bs,
- const LinearSolver::Options& options)
+ const Preconditioner::Options& options)
: options_(options),
num_blocks_(0),
num_clusters_(0),
factor_(NULL) {
CHECK_GT(options_.elimination_groups.size(), 1);
CHECK_GT(options_.elimination_groups[0], 0);
- CHECK(options_.preconditioner_type == SCHUR_JACOBI ||
- options_.preconditioner_type == CLUSTER_JACOBI ||
- options_.preconditioner_type == CLUSTER_TRIDIAGONAL)
- << "Unknown preconditioner type: " << options_.preconditioner_type;
+ CHECK(options_.type == CLUSTER_JACOBI ||
+ options_.type == CLUSTER_TRIDIAGONAL)
+ << "Unknown preconditioner type: " << options_.type;
num_blocks_ = bs.cols.size() - options_.elimination_groups[0];
CHECK_GT(num_blocks_, 0)
<< "Jacobian should have atleast 1 f_block for "
@@ -88,10 +87,7 @@
}
const time_t start_time = time(NULL);
- switch (options_.preconditioner_type) {
- case SCHUR_JACOBI:
- ComputeSchurJacobiSparsity(bs);
- break;
+ switch (options_.type) {
case CLUSTER_JACOBI:
ComputeClusterJacobiSparsity(bs);
break;
@@ -131,24 +127,6 @@
}
}
-// Determine the sparsity structure of the SCHUR_JACOBI
-// preconditioner. SCHUR_JACOBI is an extreme case of a visibility
-// based preconditioner where each camera block corresponds to a
-// cluster and there is no interaction between clusters.
-void VisibilityBasedPreconditioner::ComputeSchurJacobiSparsity(
- const CompressedRowBlockStructure& bs) {
- num_clusters_ = num_blocks_;
- cluster_membership_.resize(num_blocks_);
- cluster_pairs_.clear();
-
- // Each camea block is a member of its own cluster and the only
- // cluster pairs are the self edges (i,i).
- for (int i = 0; i < num_clusters_; ++i) {
- cluster_membership_[i] = i;
- cluster_pairs_.insert(make_pair(i, i));
- }
-}
-
// Determine the sparsity structure of the CLUSTER_JACOBI
// preconditioner. It clusters cameras using their scene
// visibility. The clusters form the diagonal blocks of the
@@ -332,7 +310,6 @@
void VisibilityBasedPreconditioner::InitEliminator(
const CompressedRowBlockStructure& bs) {
LinearSolver::Options eliminator_options;
-
eliminator_options.elimination_groups = options_.elimination_groups;
eliminator_options.num_threads = options_.num_threads;
@@ -366,13 +343,13 @@
// Compute a subset of the entries of the Schur complement.
eliminator_->Eliminate(&A, b.data(), D, m_.get(), rhs.data());
- // Try factorizing the matrix. For SCHUR_JACOBI and CLUSTER_JACOBI,
- // this should always succeed modulo some numerical/conditioning
- // problems. For CLUSTER_TRIDIAGONAL, in general the preconditioner
- // matrix as constructed is not positive definite. However, we will
- // go ahead and try factorizing it. If it works, great, otherwise we
- // scale all the cells in the preconditioner corresponding to the
- // edges in the degree-2 forest and that guarantees positive
+ // Try factorizing the matrix. For CLUSTER_JACOBI, this should
+ // always succeed modulo some numerical/conditioning problems. For
+ // CLUSTER_TRIDIAGONAL, in general the preconditioner matrix as
+ // constructed is not positive definite. However, we will go ahead
+ // and try factorizing it. If it works, great, otherwise we scale
+ // all the cells in the preconditioner corresponding to the edges in
+ // the degree-2 forest and that guarantees positive
// definiteness. The proof of this fact can be found in Lemma 1 in
// "Visibility Based Preconditioning for Bundle Adjustment".
//
@@ -382,10 +359,10 @@
// The scaling only affects the tri-diagonal case, since
// ScaleOffDiagonalBlocks only pays attenion to the cells that
- // belong to the edges of the degree-2 forest. In the SCHUR_JACOBI
- // and the CLUSTER_JACOBI cases, the preconditioner is guaranteed to
- // be positive semidefinite.
- if (!status && options_.preconditioner_type == CLUSTER_TRIDIAGONAL) {
+ // belong to the edges of the degree-2 forest. In the CLUSTER_JACOBI
+ // case, the preconditioner is guaranteed to be positive
+ // semidefinite.
+ if (!status && options_.type == CLUSTER_TRIDIAGONAL) {
VLOG(1) << "Unscaled factorization failed. Retrying with off-diagonal "
<< "scaling";
ScaleOffDiagonalCells();
