# -*- coding: utf-8 -*-
from operator import attrgetter
from typing import Set
from .base import TrackToTrackAssociator
from ..base import Property
from ..measures import Measure, Euclidean
from ..types.association import AssociationSet, TimeRangeAssociation, Association
from ..types.groundtruth import GroundTruthPath
from ..types.track import Track
from ..types.time import TimeRange
[docs]class TrackToTrack(TrackToTrackAssociator):
"""Track to track associator
Compares two sets of :class:`~.tracks`, each formed of a sequence of
:class:`~.State` objects and returns an :class:`~.Association` object for
each time at which a the two :class:`~.State` within the :class:`~.tracks`
are assessed to be associated.
Associations are triggered by track states being within a threshold
distance for a given number of timestamps. Associations are terminated when
either the two :class:`~.tracks` end or the two :class:`~.State` are
separated by a distance greater than the threshold at the next time step.
Note
----
Association is not prioritised based on historic associations or distance.
If, at a specific time step, the :class:`~.State` of one of the
:class:`~.tracks` is assessed as close to more than one track then an
:class:`~.Association` object will be return for all possible association
combinations
"""
association_threshold: float = Property(
default=10,
doc="Threshold distance measure which states must be within for an "
"association to be recorded.Default is 10")
consec_pairs_confirm: int = Property(
default=3,
doc="Number of consecutive time instances which track pairs are "
"required to be within a specified threshold in order for an "
"association to be formed. Default is 3")
consec_misses_end: int = Property(
default=2,
doc="Number of consecutive time instances which track pairs are "
"required to exceed a specified threshold in order for an "
"association to be ended. Default is 2")
measure: Measure = Property(
default=Euclidean(),
doc="Distance measure to use. Default :class:`~.measures.Euclidean()`")
[docs] def associate_tracks(self, tracks_set_1: Set[Track], tracks_set_2: Set[Track]):
"""Associate two sets of tracks together.
Parameters
----------
tracks_set_1 : set of :class:`~.Track` objects
Tracks to associate to track set 2
tracks_set_2 : set of :class:`~.Track` objects
Tracks to associate to track set 1
Returns
-------
AssociationSet
Contains a set of :class:`~.Association` objects
"""
associations = set()
for track2 in tracks_set_2:
truth_timestamps = [state.timestamp for state in track2.states]
for track1 in tracks_set_1:
track1_states = sorted(
(state
for state in track1
if state.timestamp in truth_timestamps),
key=attrgetter('timestamp'))
track_timestamps = [state.timestamp for state in track1_states]
track2_states = sorted(
(state
for state in track2
if state.timestamp in track_timestamps),
key=attrgetter('timestamp'))
if not (track1_states and track2_states):
continue
# At this point we should have two lists of states from
# track1 and 2 only at the times that they both existed
n_succesful = 0
n_unsuccesful = 0
start_timestamp = None
end_timestamp = None
# Loop through every detection pair and form associations
for state1, state2 in zip(track1_states, track2_states):
distance = self.measure(state1, state2)
if distance <= self.association_threshold:
n_succesful += 1
n_unsuccesful = 0
if n_succesful == 1:
first_timestamp = state1.timestamp
if n_succesful == self.consec_pairs_confirm:
start_timestamp = first_timestamp
else:
n_succesful = 0
n_unsuccesful += 1
if n_unsuccesful == 1:
end_timestamp = state1.timestamp
if n_unsuccesful >= self.consec_misses_end and \
start_timestamp:
associations.add(TimeRangeAssociation(
(track1, track2),
TimeRange(start_timestamp, end_timestamp)))
start_timestamp = None
# close any open associations
if start_timestamp:
end_timestamp = track1_states[-1].timestamp
associations.add(TimeRangeAssociation(
(track1, track2),
TimeRange(start_timestamp, end_timestamp)))
return AssociationSet(associations)
[docs]class TrackToTruth(TrackToTrackAssociator):
"""Track to truth associator
Compares two sets of :class:`~.Track`, each formed of a sequence of
:class:`~.State` objects and returns an :class:`~.Association` object for
each time at which a the two :class:`~.State` within the :class:`~.Track`
are assessed to be associated. Tracks are considered to be associated with
the Truth if the true :class:`~.State` is the closest to the track and
within the specified distance for a specified number of time steps.
Associations between Truth and Track if the Truth is no longer the
'closest' to the track or the distance exceeds the specified threshold for
a specified number of consecutive time steps.
Associates will be ended by consec_misses_end before any new associations
are considered even if consec_pairs_confirm < consec_misses_end
Note
----
Tracks can only be associated with one Truth (one-2-one relationship) at a
given time step however a Truth track can be associated with multiple
Tracks (one-2-many relationship).
"""
association_threshold: float = Property(
default=10,
doc="Threshold distance measure which states must be within for an "
"association to be recorded.Default is 10")
consec_pairs_confirm: int = Property(
default=3,
doc="Number of consecutive time instances which track-truth pairs are "
"required to be within a specified threshold in order for an "
"association to be formed. Default is 3")
consec_misses_end: int = Property(
default=2,
doc="Number of consecutive time instances which track-truth pairs are "
"required to exceed a specified threshold in order for an "
"association to be ended. Default is 2")
measure: Measure = Property(
default=Euclidean(),
doc="Distance measure to use. Default :class:`~.measures.Euclidean()`")
[docs] def associate_tracks(self, tracks_set: Set[Track], truth_set: Set[GroundTruthPath]):
"""Associate Tracks
Method compares to sets of :class:`~.Track` objects and will determine
associations between the two sets.
Parameters
----------
tracks_set : set of :class:`~.Track` objects
Tracks to associate to truth
truth_set : set of :class:`~.GroundTruthPath` objects
Truth to associate to tracks
Returns
-------
AssociationSet
Contains a set of :class:`~.Association` objects
"""
associations = set()
for track in tracks_set:
current_truth = None
potential_truth = None
n_potential_successes = 0
n_failures = 0
potential_start_timestep = None
start_timestamp = None
end_timestamp = None
truth_state_iters = {truth: GroundTruthPath.last_timestamp_generator(truth)
for truth in truth_set}
truth_states = {truth: next(truth_state_iter)
for truth, truth_state_iter in truth_state_iters.items()}
for track_state in Track.last_timestamp_generator(track):
min_dist = None
min_truth = None
for truth in truth_set:
if truth[0].timestamp > track_state.timestamp \
or truth[-1].timestamp < track_state.timestamp:
continue
while truth_states[truth].timestamp < track_state.timestamp:
truth_states[truth] = next(truth_state_iters[truth])
truth_state = truth_states[truth]
if truth_state.timestamp != track_state.timestamp:
continue
distance = self.measure(track_state, truth_state)
if min_dist and distance < min_dist:
min_dist = distance
min_truth = truth
elif not min_dist \
and distance < self.association_threshold:
min_dist = distance
min_truth = truth
# If there is not a truth track currently
# considered to be associated to the track
if not current_truth:
# If no truth associated then there's nothing to consider
if min_truth is None:
n_potential_successes = 0
potential_truth = None
potential_start_timestep = None
# If the latest closest truth is not being assessed
# as the likely truth make it so
elif potential_truth is not min_truth:
potential_truth = min_truth
n_potential_successes = 1
potential_start_timestep = track_state.timestamp
# Otherwise increse the number of times
# this truth appears in a row
else:
n_potential_successes += 1
# If the threshold of continuous
# similar matches has been made
if n_potential_successes >= self.consec_pairs_confirm:
current_truth = min_truth
start_timestamp = potential_start_timestep
end_timestamp = track_state.timestamp
potential_start_timestep = None
potential_truth = None
n_potential_successes = 0
# Otherwise if there is a track currently
# considered as the association
else:
# If the closest track this time is the same
# update the end time (time of last association)
if min_truth == current_truth:
n_failures = 0
end_timestamp = track_state.timestamp
# Otherwise record the failed match and how
# many times it's been the same different
# potential track in a row
else:
n_failures += 1
if min_truth and min_truth is potential_truth:
n_potential_successes += 1
else:
potential_truth = min_truth
potential_start_timestep = track_state.timestamp
n_potential_successes = 1
# If there have been enough failed matches
# in a row end the association and record
if n_failures >= self.consec_misses_end:
associations.add(TimeRangeAssociation(
(track, current_truth),
TimeRange(start_timestamp, end_timestamp)))
# If the current potential association
# is strong enough to confirm then do so
if n_potential_successes >= self.consec_pairs_confirm:
current_truth = potential_truth
start_timestamp = potential_start_timestep
end_timestamp = track_state.timestamp
else:
# Otherwise wait for a new
# association to be good enough
current_truth = None
start_timestamp = None
end_timestamp = None
# Close any open associations when the track ends
if current_truth:
associations.add(TimeRangeAssociation(
(track, current_truth),
TimeRange(start_timestamp, end_timestamp)))
return AssociationSet(associations)
[docs]class TrackIDbased(TrackToTrackAssociator):
"""Track ID based associator
Compares set of :class:`~.Track` objects to set of :class:`~.GroundTruth` objects,
each formed of a sequence of :class:`~.State` objects and returns an
:class:`~.Association` object for each time at which a the two :class:`~.State`
within the :class:`~.Track` and :class:`~.GroundTruthPath` are assessed to be associated.
Tracks are considered to be associated with the Ground Truth if the ID of the Track
is the same as the ID of the Ground Truth.
"""
[docs] def associate_tracks(self, tracks_set, truths_set):
"""Associate two sets of tracks together.
Parameters
----------
tracks_set : list of :class:`~.Track` objects
Tracks to associate to ground truths set
truths_set: list of :class:`~.GroundTruthPath` objects
Ground truths to associate to tracks set
Returns
-------
AssociationSet
Contains a set of :class:`~.Association` objects
"""
associations = set()
for track in tracks_set:
for truth in truths_set:
if track.id == truth.id:
try:
associations.add(
TimeRangeAssociation((track, truth),
TimeRange(max(track[0].timestamp,
truth[0].timestamp),
min(track[-1].timestamp,
truth[-1].timestamp))))
except (TypeError, ValueError):
# A timestamp is None, or non-overlapping timestamps (start > end)
associations.add(Association((track, truth)))
return AssociationSet(associations)