Processing Data in Complex Communication Systems 68-7
68.6 Intelligent Surveillance Systems
Today,.surveillance.has.become.a.relevant.means.for.protecting.public.and.industrial.areas.against.
malicious.subjects.like.burglars.or.vandals..For.both.keeping.privacy.of.irreproachable.citizens.as.well.
as.enabling.automated.detection.of.potential.threats,.computer-based.systems.are.needed.that.support.
human.operators.in.recognizing.unusual.situations..A.suitable.approach.for.that.purpose.is.to.utilize.
a.hierarchical.architecture.of.semantic.processing.layers.distributed.in.a.network.of.nodes..e.goal.of.
these.layers.is.to.learn.the.“normality”.in.the.environment.of.the.network,.in.order.to.detect.unusual.
situations.and.to.inform.the.human.operator.in.such.cases..e.SENSE.project.[WSe06,BKV+08].imple-
ments
.such.an.architecture..erefore,.we.will.briey.cover.it.here.as.an.example.of.how.hierarchical.
semantic.processing.can.be.used.for.surveillance.systems.
SENSE
.consists.of.a.network.of.communicating.sensor.nodes,.each.equipped.with.a.camera.and.a.
microphone.array..ese.sensor.modalities.observe.their.environment.and.deliver.streams.of.mono-modal.
events.to.a.reasoning.unit,.which.derives.fused.high-level.observations.from.this.information..ese.
observations.are.exchanged.with.neighbor.nodes.in.order.to.establish.a.global.view.about.the.commonly.
observed.environment..Detected.potential.threats.are.nally.reported.to.the.person(s).in.charge.
ough
.most.of.the.methods.used.in.the.particular.layers.are.widely.used.in.many.applications,.the.
benet.lies.in.the.combination.of.them.in.order.to.let.the.messages.of.the.system.really.appear.meaning-
ful
.to.the.user.
68.6.1 architecture
In.this.case,.an.eight-layer.data.processing.architecture.is.adopted,.in.which.the.lower.layers.are.responsible.
for.a.stable.and.comprehensive.world.representation.to.be.evaluated.in.the.higher.layers.(Figure.68.3).
First,
.the.visual.low-level.feature.extraction.(layer.0).processes.frame.by.frame.from.the.camera.in.
2D.camera.coordinates.and.extracts.predened.visual.objects..At.the.same.time,.the.audio.low-level.
extraction.scans.the.acoustic.signals.from.a.linear.eight-microphone.array.for.trained.sound.patterns.of.
predened.categories..Due.to.limited.processing.capabilities,.this.layer.can.deliver.signicantly.unstable.
data.in.both.modalities..In.case.of.unfortunate.conditions.for.the.camera,.detected.symbols.can.change.
their.label.from.one.category.to.another.and.back.for.the.same.physical.object.within.consecutive.frames..
e.size.of.detected.symbols.can.change.from.small.elements.to.large.ones.covering.tens.of.square.
60
50
40
30
20
5
0
–5
Log-likelihood Sensor values
FIGURE 68.2 Sensor.value.and.log-likelihood.for.a.single.sensor.from.the.system..Unusual.sensor.values.register.
as.drops.in.the.log-likelihood,.causing.alarms.
© 2011 by Taylor and Francis Group, LLC