GPSFactorExample.py

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"""
GTSAM Copyright 2010-2018, 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

Simple robot motion example, with prior and one GPS measurements
Author: Mandy Xie
"""
# pylint: disable=invalid-name, E1101

from __future__ import print_function

import numpy as np

import gtsam

import matplotlib.pyplot as plt
import gtsam.utils.plot as gtsam_plot

# ENU Origin is where the plane was in hold next to runway
lat0 = 33.86998
lon0 = -84.30626
h0 = 274

# Create noise models
GPS_NOISE = gtsam.noiseModel.Isotropic.Sigma(3, 0.1)
PRIOR_NOISE = gtsam.noiseModel.Isotropic.Sigma(6, 0.25)

# Create an empty nonlinear factor graph
graph = gtsam.NonlinearFactorGraph()

# Add a prior on the first point, setting it to the origin
# A prior factor consists of a mean and a noise model (covariance matrix)
priorMean = gtsam.Pose3()  # prior at origin
graph.add(gtsam.PriorFactorPose3(1, priorMean, PRIOR_NOISE))

# Add GPS factors
gps = gtsam.Point3(lat0, lon0, h0)
graph.add(gtsam.GPSFactor(1, gps, GPS_NOISE))
print("\nFactor Graph:\n{}".format(graph))

# Create the data structure to hold the initialEstimate estimate to the solution
# For illustrative purposes, these have been deliberately set to incorrect values
initial = gtsam.Values()
initial.insert(1, gtsam.Pose3())
print("\nInitial Estimate:\n{}".format(initial))

# optimize using Levenberg-Marquardt optimization
params = gtsam.LevenbergMarquardtParams()
optimizer = gtsam.LevenbergMarquardtOptimizer(graph, initial, params)
result = optimizer.optimize()
print("\nFinal Result:\n{}".format(result))