114 lines
3.8 KiB
C++
114 lines
3.8 KiB
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 SFMExampleExpressions_bal.cpp
|
|
* @brief A structure-from-motion example done with Expressions
|
|
* @author Frank Dellaert
|
|
* @date January 2015
|
|
*/
|
|
|
|
/**
|
|
* This is the Expression version of SFMExample
|
|
* See detailed description of headers there, this focuses on explaining the AD part
|
|
*/
|
|
|
|
// The two new headers that allow using our Automatic Differentiation Expression framework
|
|
#include <gtsam/slam/expressions.h>
|
|
#include <gtsam/nonlinear/ExpressionFactorGraph.h>
|
|
|
|
// Header order is close to far
|
|
#include <gtsam/inference/Symbol.h>
|
|
#include <gtsam/nonlinear/LevenbergMarquardtOptimizer.h>
|
|
#include <gtsam/sfm/SfmData.h> // for loading BAL datasets !
|
|
#include <gtsam/slam/dataset.h>
|
|
#include <vector>
|
|
|
|
using namespace std;
|
|
using namespace gtsam;
|
|
using namespace noiseModel;
|
|
using symbol_shorthand::C;
|
|
using symbol_shorthand::P;
|
|
|
|
// An SfmCamera is defined in datase.h as a camera with unknown Cal3Bundler calibration
|
|
// and has a total of 9 free parameters
|
|
|
|
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
|
|
ExpressionFactorGraph graph;
|
|
|
|
// Here we don't use a PriorFactor but directly the ExpressionFactor class
|
|
// First, we create an expression to the pose from the first camera
|
|
Expression<SfmCamera> camera0_(C(0));
|
|
// Then, to get its pose:
|
|
Pose3_ pose0_(&SfmCamera::getPose, camera0_);
|
|
// Finally, we say it should be equal to first guess
|
|
graph.addExpressionFactor(pose0_, mydata.cameras[0].pose(),
|
|
noiseModel::Isotropic::Sigma(6, 0.1));
|
|
|
|
// similarly, we create a prior on the first point
|
|
Point3_ point0_(P(0));
|
|
graph.addExpressionFactor(point0_, mydata.tracks[0].p,
|
|
noiseModel::Isotropic::Sigma(3, 0.1));
|
|
|
|
// We share *one* noiseModel between all projection factors
|
|
auto noise = noiseModel::Isotropic::Sigma(2, 1.0); // one pixel in u and v
|
|
|
|
// Simulated measurements from each camera pose, adding them to the factor
|
|
// graph
|
|
size_t j = 0;
|
|
for (const SfmTrack& track : mydata.tracks) {
|
|
// Leaf expression for j^th point
|
|
Point3_ point_('p', j);
|
|
for (const SfmMeasurement& m : track.measurements) {
|
|
size_t i = m.first;
|
|
Point2 uv = m.second;
|
|
// Leaf expression for i^th camera
|
|
Expression<SfmCamera> camera_(C(i));
|
|
// Below an expression for the prediction of the measurement:
|
|
Point2_ predict_ = project2<SfmCamera>(camera_, point_);
|
|
// Again, here we use an ExpressionFactor
|
|
graph.addExpressionFactor(predict_, uv, noise);
|
|
}
|
|
j += 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;
|
|
}
|