gtsam/examples/SFMExample_bal_COLAMD_METIS...

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C++

/* ----------------------------------------------------------------------------
* GTSAM Copyright 2010, Georgia Tech Research Corporation,
* Atlanta, Georgia 30332-0415
* All Rights Reserved
* Authors: Frank Dellaert, et al. (see THANKS for the full author list)
* See LICENSE for the license information
* -------------------------------------------------------------------------- */
/**
* @file SFMExample.cpp
* @brief This file is to compare the ordering performance for COLAMD vs METIS.
* Example problem is to solve a structure-from-motion problem from a "Bundle Adjustment in the Large" file.
* @author Frank Dellaert, Zhaoyang Lv
*/
// For an explanation of headers, see SFMExample.cpp
#include <gtsam/inference/Symbol.h>
#include <gtsam/inference/Ordering.h>
#include <gtsam/nonlinear/NonlinearFactorGraph.h>
#include <gtsam/nonlinear/LevenbergMarquardtOptimizer.h>
#include <gtsam/slam/PriorFactor.h>
#include <gtsam/slam/GeneralSFMFactor.h>
#include <gtsam/slam/dataset.h> // for loading BAL datasets !
#include <vector>
using namespace std;
using namespace gtsam;
using symbol_shorthand::C;
using symbol_shorthand::P;
// We will be using a projection factor that ties a SFM_Camera to a 3D point.
// An SFM_Camera is defined in datase.h as a camera with unknown Cal3Bundler calibration
// and has a total of 9 free parameters
typedef GeneralSFMFactor<SfM_Camera,Point3> MyFactor;
/* ************************************************************************* */
int main (int argc, char* argv[]) {
// Find default file, but if an argument is given, try loading a file
string filename = findExampleDataFile("dubrovnik-3-7-pre");
if (argc>1) filename = string(argv[1]);
// Load the SfM data from file
SfM_data mydata;
readBAL(filename, mydata);
cout << boost::format("read %1% tracks on %2% cameras\n") % mydata.number_tracks() % mydata.number_cameras();
// Create a factor graph
NonlinearFactorGraph graph;
// We share *one* noiseModel between all projection factors
noiseModel::Isotropic::shared_ptr noise =
noiseModel::Isotropic::Sigma(2, 1.0); // one pixel in u and v
// Add measurements to the factor graph
size_t j = 0;
BOOST_FOREACH(const SfM_Track& track, mydata.tracks) {
BOOST_FOREACH(const SfM_Measurement& m, track.measurements) {
size_t i = m.first;
Point2 uv = m.second;
graph.push_back(MyFactor(uv, noise, C(i), P(j))); // note use of shorthand symbols C and P
}
j += 1;
}
// Add a prior on pose x1. This indirectly specifies where the origin is.
// and a prior on the position of the first landmark to fix the scale
graph.push_back(PriorFactor<SfM_Camera>(C(0), mydata.cameras[0], noiseModel::Isotropic::Sigma(9, 0.1)));
graph.push_back(PriorFactor<Point3> (P(0), mydata.tracks[0].p, noiseModel::Isotropic::Sigma(3, 0.1)));
// Create initial estimate
Values initial;
size_t i = 0; j = 0;
BOOST_FOREACH(const SfM_Camera& camera, mydata.cameras) initial.insert(C(i++), camera);
BOOST_FOREACH(const SfM_Track& track, mydata.tracks) initial.insert(P(j++), track.p);
/** --------------- COMPARISON -----------------------**/
/** ----------------------------------------------------**/
double t_COLAMD_ordering, t_METIS_ordering; //, t_NATURAL_ordering;
LevenbergMarquardtParams params_using_COLAMD, params_using_METIS, params_using_NATURAL;
try {
double tic_t = clock();
params_using_METIS.setVerbosity("ERROR");
params_using_METIS.ordering = Ordering::Create(Ordering::METIS, graph);
t_METIS_ordering = (clock() - tic_t)/CLOCKS_PER_SEC;
tic_t = clock();
params_using_COLAMD.setVerbosity("ERROR");
params_using_COLAMD.ordering = Ordering::Create(Ordering::COLAMD, graph);
t_COLAMD_ordering = (clock() - tic_t)/CLOCKS_PER_SEC;
// tic_t = clock();
// params_using_NATURAL.setVerbosity("ERROR");
// params_using_NATURAL.ordering = Ordering::Create(Ordering::NATURAL, graph);
// t_NATURAL_ordering = (clock() - tic_t)/CLOCKS_PER_SEC;
} catch (exception& e) {
cout << e.what();
}
// expect they have different ordering results
if(params_using_COLAMD.ordering == params_using_METIS.ordering) {
cout << "COLAMD and METIS produce the same ordering. "
<< "Problem here!!!" << endl;
}
/* with METIS, optimize the graph and print the results */
cout << "Optimize with METIS" << endl;
Values result_METIS;
double t_METIS_solving;
try {
double tic_t = clock();
LevenbergMarquardtOptimizer lm_METIS(graph, initial, params_using_COLAMD);
result_METIS = lm_METIS.optimize();
t_METIS_solving = (clock() - tic_t)/CLOCKS_PER_SEC;
} catch (exception& e) {
cout << e.what();
}
/* With COLAMD, optimize the graph and print the results */
cout << "Optimize with COLAMD..." << endl;
Values result_COLAMD;
double t_COLAMD_solving;
try {
double tic_t = clock();
LevenbergMarquardtOptimizer lm_COLAMD(graph, initial, params_using_COLAMD);
result_COLAMD = lm_COLAMD.optimize();
t_COLAMD_solving = (clock() - tic_t)/CLOCKS_PER_SEC;
} catch (exception& e) {
cout << e.what();
}
// disable optimizer with NATURAL since it doesn't converge on large problem
/* Use Natural ordering and solve both respectively */
// cout << "Solving with natural ordering: " << endl;
// Values result_NATURAL;
// double t_NATURAL_solving;
// try {
// double tic_t = clock();
// LevenbergMarquardtOptimizer lm_NATURAL(graph, initial, params_using_NATURAL);
// result_NATURAL = lm_NATURAL.optimize();
// t_NATURAL_solving = (clock() - tic_t)/CLOCKS_PER_SEC;
// } catch (exception& e) {
// cout << e.what();
// }
cout << endl << endl;
{
// printing the result
cout << "Time comparison by solving " << filename << " results:" << endl;
cout << boost::format("%1% point tracks and %2% cameras\n") \
% mydata.number_tracks() % mydata.number_cameras() \
<< endl;
cout << "COLAMD: " << endl;
cout << "Ordering: " << t_COLAMD_ordering << "seconds" << endl;
cout << "Solving: " << t_COLAMD_solving << "seconds" << endl;
cout << "final error: " << graph.error(result_COLAMD) << endl;
cout << "METIS: " << endl;
cout << "Ordering: " << t_METIS_ordering << "seconds" << endl;
cout << "Solving: " << t_METIS_solving << "seconds" << endl;
cout << "final error: " << graph.error(result_METIS) << endl;
// cout << "Natural: " << endl;
// cout << "Ordering: " << t_NATURAL_ordering << "seconds" << endl;
// cout << "Solving: " << t_NATURAL_solving << "seconds" << endl;
// cout << "final error: " << graph.error(result_NATURAL) << endl;
}
return 0;
}
/* ************************************************************************* */