Pose3SLAMExample_g2o.py

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"""
 * @file Pose3SLAMExample_initializePose3.cpp
 * @brief A 3D Pose SLAM example that reads input from g2o, and initializes the
 *  Pose3 using InitializePose3
 * @date Jan 17, 2019
 * @author Vikrant Shah based on CPP example by Luca Carlone
"""
# pylint: disable=invalid-name, E1101
 
from __future__ import print_function
 
import argparse
 
import gtsam
import matplotlib.pyplot as plt
import numpy as np
from gtsam.utils import plot
from mpl_toolkits.mplot3d import Axes3D
 
 
def vector6(x, y, z, a, b, c):
    """Create 6d double numpy array."""
    return np.array([x, y, z, a, b, c], dtype=float)
 
 
def main():
    """Main runner."""
 
    parser = argparse.ArgumentParser(
        description="A 3D Pose SLAM example that reads input from g2o, and "
        "initializes Pose3")
    parser.add_argument('-i', '--input', help='input file g2o format')
    parser.add_argument(
        '-o',
        '--output',
        help="the path to the output file with optimized graph")
    parser.add_argument("-p",
                        "--plot",
                        action="store_true",
                        help="Flag to plot results")
    args = parser.parse_args()
 
    g2oFile = gtsam.findExampleDataFile("pose3example.txt") if args.input is None \
        else args.input
 
    is3D = True
    graph, initial = gtsam.readG2o(g2oFile, is3D)
 
    # Add Prior on the first key
    priorModel = gtsam.noiseModel.Diagonal.Variances(
        vector6(1e-6, 1e-6, 1e-6, 1e-4, 1e-4, 1e-4))
 
    print("Adding prior to g2o file ")
    firstKey = initial.keys()[0]
    graph.add(gtsam.PriorFactorPose3(firstKey, gtsam.Pose3(), priorModel))
 
    params = gtsam.GaussNewtonParams()
    params.setVerbosity(
        "Termination")  # this will show info about stopping conds
    optimizer = gtsam.GaussNewtonOptimizer(graph, initial, params)
    result = optimizer.optimize()
    print("Optimization complete")
 
    print("initial error = ", graph.error(initial))
    print("final error = ", graph.error(result))
 
    if args.output is None:
        print("Final Result:\n{}".format(result))
    else:
        outputFile = args.output
        print("Writing results to file: ", outputFile)
        graphNoKernel, _ = gtsam.readG2o(g2oFile, is3D)
        gtsam.writeG2o(graphNoKernel, result, outputFile)
        print("Done!")
 
    if args.plot:
        resultPoses = gtsam.utilities.allPose3s(result)
        for i in range(resultPoses.size()):
            plot.plot_pose3(1, resultPoses.atPose3(i))
        plt.show()
 
 
if __name__ == "__main__":
    main()