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/* ----------------------------------------------------------------------------
* 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_bal.cpp
* @brief Solve a structure-from-motion problem from a "Bundle Adjustment in the Large" file
* @author Frank Dellaert
*/
// For an explanation of headers, see SFMExample.cpp
#include <gtsam/sfm/SfmData.h> // for loading BAL datasets !
#include <gtsam/slam/GeneralSFMFactor.h>
#include <gtsam/slam/dataset.h>
#include <gtsam/nonlinear/NonlinearFactorGraph.h>
#include <gtsam/nonlinear/LevenbergMarquardtOptimizer.h>
#include <gtsam/inference/Symbol.h>
#include <boost/format.hpp>
#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<SfmCamera,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
SfmData mydata = SfmData::FromBalFile(filename);
cout << boost::format("read %1% tracks on %2% cameras\n") % mydata.numberTracks() % mydata.numberCameras();
// Create a factor graph
NonlinearFactorGraph graph;
// We share *one* noiseModel between all projection factors
auto noise =
noiseModel::Isotropic::Sigma(2, 1.0); // one pixel in u and v
// Add measurements to the factor graph
size_t j = 0;
for(const SfmTrack& track: mydata.tracks) {
for(const SfmMeasurement& m: track.measurements) {
size_t i = m.first;
Point2 uv = m.second;
graph.emplace_shared<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.addPrior(C(0), mydata.cameras[0], noiseModel::Isotropic::Sigma(9, 0.1));
graph.addPrior(P(0), mydata.tracks[0].p, noiseModel::Isotropic::Sigma(3, 0.1));
// Create initial estimate
Values initial;
size_t i = 0; j = 0;
for(const SfmCamera& camera: mydata.cameras) initial.insert(C(i++), camera);
for(const SfmTrack& track: mydata.tracks) initial.insert(P(j++), track.p);
/* Optimize the graph and print results */
Values result;
try {
LevenbergMarquardtParams params;
params.setVerbosity("ERROR");
LevenbergMarquardtOptimizer lm(graph, initial, params);
result = lm.optimize();
} catch (exception& e) {
cout << e.what();
}
cout << "final error: " << graph.error(result) << endl;
return 0;
}
/* ************************************************************************* */
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