forked from luigifreda/pyslam
/
motion_model.py
executable file
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motion_model.py
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"""
* This file is part of PYSLAM
* This file contains a revised and fixed version of the class in https://github.com/uoip/stereo_ptam/blob/master/motion.py
*
* Copyright (C) 2016-present Luigi Freda <luigi dot freda at gmail dot com>
*
* PYSLAM is free software: you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation, either version 3 of the License, or
* (at your option) any later version.
*
* PYSLAM is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with PYSLAM. If not, see <http://www.gnu.org/licenses/>.
"""
import numpy as np
import g2o
class MotionModelBase(object):
def __init__(self,
timestamp=None,
initial_position=None,
initial_orientation=None,
initial_covariance=None):
self.timestamp = timestamp
if initial_position is not None:
self.position = initial_position
else:
self.position = np.zeros(3)
if initial_orientation is not None:
self.orientation = initial_orientation
else:
self.orientation = g2o.Quaternion()
self.orientation = initial_orientation
self.covariance = initial_covariance # pose covariance
self.is_ok = False
self.initialized = False
def current_pose(self):
'''
Get the current camera pose.
'''
return (g2o.Isometry3d(self.orientation, self.position), self.covariance)
def predict_pose(self, timestamp, prev_position=None, prev_orientation=None):
return None
def update_pose(self, timestamp, new_position, new_orientation, new_covariance=None):
return None
# correction= Tcw_old.inverse() * Tcw_new (transform from world_new to worl_old)
def apply_correction(self, correction): # corr: g2o.Isometry3d or matrix44
return None
# simple kinematic motion model without damping (does not actually use timestamps)
class MotionModel(MotionModelBase):
def __init__(self,
timestamp=None,
initial_position=None,
initial_orientation=None,
initial_covariance=None):
super().__init__(timestamp, initial_position, initial_orientation, initial_covariance)
self.delta_position = np.zeros(3) # delta translation
self.delta_orientation = g2o.Quaternion()
def predict_pose(self, timestamp, prev_position=None, prev_orientation=None):
'''
Predict the next camera pose.
'''
if prev_position is not None:
self.position = prev_position
if prev_orientation is not None:
self.orientation = prev_orientation
if not self.initialized:
return (g2o.Isometry3d(self.orientation, self.position), self.covariance)
orientation = self.delta_orientation * self.orientation
position = self.position + self.delta_orientation * self.delta_position
return (g2o.Isometry3d(orientation, position), self.covariance)
def update_pose(self, timestamp, new_position, new_orientation, new_covariance=None):
'''
Update the motion model when given a new camera pose.
'''
if self.initialized:
self.delta_position = new_position - self.position
self.delta_orientation = new_orientation * self.orientation.inverse()
self.delta_orientation.normalize()
self.timestamp = timestamp
self.position = new_position
self.orientation = new_orientation
self.covariance = new_covariance
self.initialized = True
# correction= Tcw_corrected * Tcw_uncorrected.inverse() (transform from camera_uncorrected to camera_corrected)
def apply_correction(self, correction): # corr: g2o.Isometry3d or matrix44
'''
Reset the model given a new camera pose.
Note: This method will be called when it happens an abrupt change in the pose (LoopClosing)
'''
if not isinstance(correction, g2o.Isometry3d):
correction = g2o.Isometry3d(correction)
current = g2o.Isometry3d(self.orientation, self.position)
current = correction * current
self.position = current.position()
self.orientation = current.orientation()
# correction= Tcw_corrected * Tcw_uncorrected.inverse() (transform from camera_uncorrected to camera_corrected)
self.delta_orientation = correction.orientation() * self.delta_orientation
self.delta_position = correction.orientation() * self.delta_position
# motion model with damping
class MotionModelDamping(MotionModelBase):
def __init__(self,
timestamp=None,
initial_position=None,
initial_orientation=None,
initial_covariance=None,
damping=0.95):
super().__init__(timestamp, initial_position, initial_orientation, initial_covariance)
self.v_linear = np.zeros(3) # linear velocity
self.v_angular_angle = 0
self.v_angular_axis = np.array([1, 0, 0])
self.damp = damping # damping factor
def predict_pose(self, timestamp, prev_position=None, prev_orientation=None):
'''
Predict the next camera pose.
'''
if prev_position is not None:
self.position = prev_position
if prev_orientation is not None:
self.orientation = prev_orientation
if not self.initialized:
return (g2o.Isometry3d(self.orientation, self.position), self.covariance)
dt = timestamp - self.timestamp
delta_angle = g2o.AngleAxis(
self.v_angular_angle * dt * self.damp,
self.v_angular_axis)
delta_orientation = g2o.Quaternion(delta_angle)
orientation = delta_orientation * self.orientation
position = self.position + delta_orientation * (self.v_linear * dt * self.damp)
return (g2o.Isometry3d(orientation, position), self.covariance)
def update_pose(self, timestamp, new_position, new_orientation, new_covariance=None):
'''
Update the motion model when given a new camera pose.
'''
if self.initialized:
dt = timestamp - self.timestamp
assert dt != 0
v_linear = (new_position - self.position) / dt
self.v_linear = v_linear
delta_q = new_orientation * self.orientation.inverse()
delta_q.normalize()
delta_angle = g2o.AngleAxis(delta_q)
angle = delta_angle.angle()
axis = delta_angle.axis()
if angle > np.pi:
axis = axis * -1
angle = 2 * np.pi - angle
self.v_angular_axis = axis
self.v_angular_angle = angle / dt
self.timestamp = timestamp
self.position = new_position
self.orientation = new_orientation
self.covariance = new_covariance
self.initialized = True
# correction= Tcw_corrected * Tcw_uncorrected.inverse() (transform from camera_uncorrected to camera_corrected)
def apply_correction(self, correction): # corr: g2o.Isometry3d or matrix44
'''
Reset the model given a new camera pose.
Note: This method will be called when it happens an abrupt change in the pose (LoopClosing)
'''
if not isinstance(correction, g2o.Isometry3d):
correction = g2o.Isometry3d(correction)
current = g2o.Isometry3d(self.orientation, self.position)
current = correction * current
self.position = current.position()
self.orientation = current.orientation()
# correction= Tcw_corrected * Tcw_uncorrected.inverse() (transform from camera_uncorrected to camera_corrected)
self.v_angular_axis = correction.orientation() * self.v_angular_axis
self.v_linear = correction.orientation() * self.v_linear