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/**
* @file Pose3SLAMExampleExpressions_BearingRangeWithTransform.cpp
* @brief A simultaneous optimization of trajectory, landmarks and sensor-pose with respect to body-pose using bearing-range measurements done with Expressions
* @author Thomas Horstink
* @date January 4th, 2019
*/
#include <gtsam/inference/Symbol.h>
#include <gtsam/geometry/BearingRange.h>
#include <gtsam/slam/expressions.h>
#include <gtsam/nonlinear/ExpressionFactorGraph.h>
#include <gtsam/nonlinear/LevenbergMarquardtOptimizer.h>
#include <gtsam/nonlinear/Values.h>
#include <examples/SFMdata.h>
using namespace gtsam;
typedef BearingRange<Pose3, Point3> BearingRange3D;
/* ************************************************************************* */
int main(int argc, char* argv[]) {
// Move around so the whole state (including the sensor tf) is observable
Pose3 init_pose = Pose3();
Pose3 delta_pose1 = Pose3(Rot3().Yaw(2*M_PI/8).Pitch(M_PI/8), Point3(1, 0, 0));
Pose3 delta_pose2 = Pose3(Rot3().Pitch(-M_PI/8), Point3(1, 0, 0));
Pose3 delta_pose3 = Pose3(Rot3().Yaw(-2*M_PI/8), Point3(1, 0, 0));
int steps = 4;
auto poses = createPoses(init_pose, delta_pose1, steps);
auto poses2 = createPoses(init_pose, delta_pose2, steps);
auto poses3 = createPoses(init_pose, delta_pose3, steps);
// Concatenate poses to create trajectory
poses.insert( poses.end(), poses2.begin(), poses2.end() );
poses.insert( poses.end(), poses3.begin(), poses3.end() ); // std::vector of Pose3
auto points = createPoints(); // std::vector of Point3
// (ground-truth) sensor pose in body frame, further an unknown variable
Pose3 body_T_sensor_gt(Rot3::RzRyRx(-M_PI_2, 0.0, -M_PI_2), Point3(0.25, -0.10, 1.0));
// The graph
ExpressionFactorGraph graph;
// Specify uncertainty on first pose prior and also for between factor (simplicity reasons)
auto poseNoise = noiseModel::Diagonal::Sigmas((Vector(6)<<0.3,0.3,0.3,0.1,0.1,0.1).finished());
// Uncertainty bearing range measurement;
auto bearingRangeNoise = noiseModel::Diagonal::Sigmas((Vector(3)<<0.01,0.03,0.05).finished());
// Expressions for body-frame at key 0 and sensor-tf
Pose3_ x_('x', 0);
Pose3_ body_T_sensor_('T', 0);
// Add a prior on the body-pose
graph.addExpressionFactor(x_, poses[0], poseNoise);
// Simulated measurements from pose
for (size_t i = 0; i < poses.size(); ++i) {
auto world_T_sensor = poses[i].compose(body_T_sensor_gt);
for (size_t j = 0; j < points.size(); ++j) {
// This expression is the key feature of this example: it creates a differentiable expression of the measurement after being displaced by sensor transform.
auto prediction_ = Expression<BearingRange3D>( BearingRange3D::Measure, Pose3_('x',i)*body_T_sensor_, Point3_('l',j));
// Create a *perfect* measurement
auto measurement = BearingRange3D(world_T_sensor.bearing(points[j]), world_T_sensor.range(points[j]));
// Add factor
graph.addExpressionFactor(prediction_, measurement, bearingRangeNoise);
}
// and add a between factor to the graph
if (i > 0)
{
// And also we have a *perfect* measurement for the between factor.
graph.addExpressionFactor(between(Pose3_('x', i-1),Pose3_('x', i)), poses[i-1].between(poses[i]), poseNoise);
}
}
// Create perturbed initial
Values initial;
Pose3 delta(Rot3::Rodrigues(-0.1, 0.2, 0.25), Point3(0.05, -0.10, 0.20));
for (size_t i = 0; i < poses.size(); ++i)
initial.insert(Symbol('x', i), poses[i].compose(delta));
for (size_t j = 0; j < points.size(); ++j)
initial.insert<Point3>(Symbol('l', j), points[j] + Point3(-0.25, 0.20, 0.15));
// Initialize body_T_sensor wrongly (because we do not know!)
initial.insert<Pose3>(Symbol('T',0), Pose3());
std::cout << "initial error: " << graph.error(initial) << std::endl;
Values result = LevenbergMarquardtOptimizer(graph, initial).optimize();
std::cout << "final error: " << graph.error(result) << std::endl;
initial.at<Pose3>(Symbol('T',0)).print("\nInitial estimate body_T_sensor\n"); /* initial sensor_P_body estimate */
result.at<Pose3>(Symbol('T',0)).print("\nFinal estimate body_T_sensor\n"); /* optimized sensor_P_body estimate */
body_T_sensor_gt.print("\nGround truth body_T_sensor\n"); /* sensor_P_body ground truth */
return 0;
}
/* ************************************************************************* */
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